Neuroscience Final

Front 1

What is Motor Control?

Back 1

What is Motor Control?

Motor Control is the study of how individuals (and animals) reliably make accurate, goal-directed movements. It is the ability to regulate or direct the neural mechanisms necessary for volitional movement.

Front 2

Motor Control includes:

Back 2

the Perceptions, Actions and Cognitive Processes that integrate perception with action.
Perception: what sensory afference is used and how does it influence the choice of movement, its control during movement execution, and learning.
Cognition: what processes are involved in the choice to move—when, how, why—and establishing the goal or intent to move.
Action: what is the motor output to the muscles? How does the nervous translate a goal into a movement command that becomes a set of muscle contractions?

Front 3

Sources of evidence about Motor Control

Back 3

Sources of evidence about Motor Control
Neurophysiology—record from behaving animals, stimulate a region and observe the behavior; observe behaving people and image the brain with fMRI or stimulate with TMS.
Clinical Science Neurology—movement dysfunction associated with lesions and disease to determine what a structure does.
NeuroPsychology—behavioral psychology and cognitive psychology
Biomechanics—kinematics, kinetics (EMG, Torques) of produced motions.

Front 4

The neural basis of movement examines how

Back 4

The neural basis of movement examines how different regions of the brain and spinal cord control the motor output that become the different movements observed. Reach to grasp, manipulation, postural control and locomotion are created by a differentially weighted combination of neural structures distributed across the neuraxis.

Front 5

2. How does volitional movement differ as a category from the other categories of motor actions (i.e., reflex, automatic responses, synergies, cpg’s)?

Back 5

2. How does volitional movement differ s a category from the other categories of motor actions (i.e., reflex, automatic responses, synergies, cpg’s)?

Volitional Movement—is goal oriented and voluntarily initiated to meet a need, solve a motor problem, get what you want, go where you want to go when you want it. compare to the Categories of actions from Module 3 Topic 2 Motor Systems

Volitional movement meets the task goals and characteristics of the environment—and the musculoskeletal state of the body.

Novelty—variety of expression only limited by the biomechanical apparatus, body state, and environmental constraint. It’s what gives us our individuality in terms of movements we can perform—tennis, golf, knitting, race car driving.

Improves with practice over time—relatively permanent changes in motor behavior, newlyacquired actions that last a lifetime (ride a bike!).

Front 6

What are the streams in the cerebral cortex?

Back 6

lower sensory send input to the parietal (dorsal stream) association cortex and the temporal (ventral stream) association cortex, which then project to dorsal and ventral areas of the frontal cortex. The dorsal areas (info from parietal) are involved in motor and executive functions for which spatial information is important, while the ventral areas mediate emotional responses. Emotional significance can be applied to an object only after that object has been identified, a process that depends on regions of the temporal lobe.

Front 7

What is the importance of the parietal association cortex?
Temporal AC?
Frontal?
Limbic AC?

Back 7

Parietal association cortex - sensory guidance of motor behavior and spatial awareness
Temporal AC - recognition of sensory stimuli and storage of semantic (factual) knowledge
Frontal AC - key role in organizing behavior and in working memory
Limbic AC - complex function related to emotion and episodic (autobiographical) memories

Front 8

Relationship between Cortical level Sensory Systems (in blue on the left) and Motor Systems (In red on the right) during volitional movement:

Back 8

Relationship between Cortical level Sensory Systems (in blue on the left) and Motor Systems (In red on the right) during volitional movement: In the middle (purple), the decision areas refer to the different association cortices (Pre-Frontal: goal selection, intention; Parietal-Occipital AC & Temporal-Occipital AC: Interpretation of sensation; Limbic/Orbito-frontal: emotions, memory processing) that integrate the sensory information with prior experience to make the choice to move.

Front 9

4. What are the different ways to categorize motor skills/volitional movements?

Back 9

4. What are the different ways to categorize motor skills/volitional movements?

The motions you observe can be placed into each of these 3 categories:
#1: Open vs. Closed
#2: Discrete vs. Serial vs. Continuous
#3: Three functional Categories of Volitional movement

Skilled motion: Reach/Grasp/Manipulation—interact with objects in the environment

Locomotion—body transport, continuous, repetitive rhythmic stepping

Postural Control—manage body vs. gravity AND Maintain visual orientation to task

Front 10

#3: Three functional Categories of Volitional movement

Back 10

#3: Three functional Categories of Volitional movement

Skilled motion: Reach/Grasp/Manipulation—interact with objects in the environment

Locomotion—body transport, continuous, repetitive rhythmic stepping

Postural Control—manage body vs. gravity AND Maintain visual orientation to task

Front 11

Three Functional Categories of Volitional Movement differ by:

Back 11

Three Functional Categories of Volitional Movement—differ by:

Purpose—goal of the movement —the TASK (see next slide)

Observable expression—movements you see

Motor systems that plan them and execute them--includes the cortex AND subcortical structures.

Contributions of the sensory systems that monitor them (feedback) and provide feed-forward inputs.

The specific movement corrections that may be implemented during the movement to save the goal/achieve the task.

Front 12

General purpose/goals of the 3 different functional categories of volitional movement:

Back 12

Reach to grasp—get hand in right place, right time, right shape to interact with object.
External driven: Reach to Grasp Visuomotor transformation
Manipulation—pick up/hold with right amount of grip & load forces to hold on & lift the object without dropping, crushing, or throwing.
Internal driven: Manipulation Sensorimotor transformation
Locomotion—use a repetitive/continuous reciprocal limb pattern to transport the body from point A to point B
External driven (navigate through the room around/over obstacles)
Internal driven (walking while texting)
Postural Control/Balance—maintain level eyes/head (Alignment/Gaze), maintain alignment of body parts to each & against gravity (COM in BOS), maintain prox stab for dist mob (P Tone). Mix int. & ext. drive.
components of postural control involved in all other volitional -Anticipatory Postural Set
monitor and restore postural control - Reactive Postural responses
Postural Tone or readiness to move against gravity

Front 13

5. What are the three phases of volitional movement [and what happens during each phase]?

Back 13

Before you see the volitional movement appear/EMG in the muscles

During - Recruit the spinal cord circuits and alpha/lower motor neurons
and
After - the movement is finished

Front 14

5. [What are the three phases of volitional movement and] what happens during each phase?

Back 14

THE PHASES OF VOLITIONAL MOVEMENT overview of steps involved:
BEFORE you see the volitional movement appear/EMG in the muscles
-PERCEPTIONCOGNITION Decision to move in the Association Cortices
COGNITONACTION Supra-spinal structures plan the movement motor command & sensory expectations.


DURING Recruit the spinal cord circuits and alpha/lower motor neurons
Execute the plan: Send the motor command via the descending tracts to the effectors in the spinal cord—synergies, cpg’s, interneurons, alpha motor neurons.
Motor units fire to execute the motion by muscle contractions

Sensory afference monitors motor performance for ongoing performance and feedback corrections during motion.

AFTER the movement is finished
Record/Retain sensory afference and results of movement to update the internal model for next movement.

Front 15

6. What is the difference between Innate & Acquired Motor Programs vs. Instantaneous Motor Plans?
 
#1: Types of Innate Motor Programs—

Back 15

#1: Types of Innate Motor Programs—patterns of movement/motor acts that are incorporated into volitional movement—categories of motor actions.
Have a hierarchy as they are distributed throughout the different layers of the motor systems (from Motor Systems lecture: What can each level do? Reflexes, automatic responses, synergies, cpg’s)
Repeatable/stereotypical
Modifiable—tuned to the volitional movement goal and the sensory information needed
Incorporated into instantaneous motor plans—practice improves recruitment of them
Cortical level—well-learned acquired motions SMA -M1
Trajectories of behaviorally relevant motions when stimulating in PMAM1Graziano’s monkeys
Brain stem level—Automatic Reactions, CPG’s
Spinal Cord level motor programs—CPG’s, synergies, reflexes
Hierarchy means:
Level of complexity of the interpretation or the motor output—can do “more” Rather than ‘higher” in function

Front 16

6. What is the difference between Innate & Acquired Motor Programs vs. Instantaneous Motor Plans?
#2: Instantaneous motor plan

Back 16

#2: Instantaneous motor plan for a volitional movement: Innate and acquired motor programs are incorporated into instantaneous motor plans to execute the motor commands. Motor plans are created for a volitional movement. (see next slide)

Front 17

What are the components of the Instantaneous Motor Plan?

Back 17

What are the components of the Instantaneous Motor Plan? Movement goal becomes translated to a plan that specifies what motor patterns/acts (including innate motor programs) to use, how to put them together AND how it is supposed to turn out it includes:

DESCENDING MOTOR COMMAND: where to move, what to move, when/how (timing, amounts),
A. Movement set
B. Postural Set—anticipates the effect that the motion will have on postural control

FORWARD INTERNAL MODEL: Expectations/prediction of the sensory consequences that will be caused by the motor command. Therefore the entire neuraxis is tuned into what to monitor based on what it should be like and when.
A. efference copy of the movement planned
B. forward model or predicted sensory afference/expectations corollary discharge

Front 18

What you want gets transformed into a motor plan - the______ MODEL which then becomes the

At the same time, a copy of the motor command _____ COPY gets transformed into a FORWARD MODEL which is

Back 18

What you want gets transformed into a motor plan - the INVERSE MODEL which then becomes the descending MOTOR COMMAND to the motor pools to get you to move—and achieve the goal you want as a result of moving.

At the same time, a copy of the motor command EFFERENCE COPY gets transformed into a FORWARD MODEL which is SENSORY PREDICTION or expectations of the sensory events that will occur if the motor command AND the internal model it is based on are accurate.
a.k.a. COROLLARY DISCHARGE

Front 19

“Prediction and control are two sides of the same coin and the two processes map exactly onto ____ and ____ models. Prediction turns motor commands into

Back 19

“Prediction and control are two sides of the same coin and the two processes map exactly onto forward and inverse models. Prediction turns motor commands into expected sensory consequences, whereas control turns desired sensory consequences into motor commands.”

Front 20

Motor Planning: Getting it right the first time.
Planning generates a

Back 20

Motor Planning: Getting it right the first time.
Planning generates a motor command and a sensory prediction of how the movement will go based upon past experience (internal model) and the current sensory situation (feedforward afference).

Front 21

8. What is the relationship between sensation and movement? Feedforward Sensory Afference for Anticipatory Motor Control vs. Feedback Sensory Afference for Reactive Motor Control/

Back 21

8. What is the relationship between sensation and movement? Feedforward Sensory Afference for Anticipatory Motor Control vs. Feedback Sensory Afference for Reactive Motor Control/

Feedforward sensory afference”the perceptual read” of the task & environmental demands in order to choose to move and to plan a movement that will then match the environment, meet the task demand. Combined with past experiences (internal models) to develop a motor plan.

Used:
Before movement initiated
Anticipatory motor control
Motor Planning

Feedback sensory afference keeps the task going (especially if serial or continuous) it going OR fix or adjust movement if the actual afference does not meet the prediction.

Used:
Ongoing movement is modifiable by sensory inputs—all of them
Reactive motor control
Motor execution/monitoring
Sensory recording after the movement to update the internal model

Front 22

Question: What is the difference between the feed-forward sensory afference used for motor planning and the sensory afference used in the association cortices to make a decision to move?

Answer:

Back 22

Question: What is the difference between the feed-forward sensory afference used for motor planning and the sensory afference used in the association cortices to make a decision to move?

Answer: There is no difference. The same feedforward info is used simultaneously. “Choosing to move” and “planning the movement” for simplicity are depicted as sequential; however, they are parallel processes occurring simultaneously, using the same sensory inputs.

Front 23

8.1: Question: How do we get it right the first time? How does the nervous system produce a lifetime of accurate movements?

Back 23

Answer: Feed-forward anticipatory motor control creates a motor plan and sensory predictions of the effect of the motor command in order to produce a movement that will meet the TASK goal within the ENVIRONMENTAL context and current INDIVIDUAL status (i.e., start position) using your individual capacity to move
That plan is based upon incoming sensory afference about the current situation (“the perceptual read” both external and internal) combined with all of the stored past experience/memories of movements previously donethe stored internal models.

the plan takes into account the effect the motion will have on balance/postural control and incorporates anticipatory postural set changes postural set

the plan generates a predictive or forward internal model of the motion based on the expected afference. “how it should feel’ as well as “what to do” forward model of sensory consequences before sensory feedback is available.

Front 24

When we watched the videos of tennis player, Roger Federer, we were amazed by what anticipatory feed-forward motor control can do!
3 aspects

Back 24

When we watched the videos of tennis player, Roger Federer, we were amazed by what anticipatory feed-forward motor control can do!
the consistent accuracy of his motions on the tennis court AND the choices he makes when he hits the ball—the ball goes where he wants it to go.
his capacity to predict where his opponent will go next AND to get to where the ball will be when he must return it.
the quality of his movements on the court—not only hitting the ball, but running, turning, jumping, and balance/postural control.

Front 25

8.2 Question: How do we keep a movement going OR know if a mistake has occurred?

Answer:

Back 25

Sensory Feedback during the motion compared to the forward model/predicted sensory consequences. The motor regions and the entire neuraxis is tuned and ready to listen for the sensory afference expected from that motor plan in order to ensure the goal of the movement is achieved.
The forward model (corollary discharge created from the efference copy) predicts the consequences of the actions made by the motor command before sensory feedback is available. This sets up the nervous system to be ready for that feedback when it is supposed to occur.
If the feedback comes in at the right time & as expected, motor plan can carry on.
If feedback is early/delayed or not as expected (i.e., too much, not enough) then the plan can be adjusted/a correction can be implemented right when it needs to be (without delay) to ensure the movement goal can still be met
Sensory afference is delivered the regions that will make corrections during the movement as well as record after the motion is complet

Front 26

“The perfect hot shower” AN ANALOGY to help to explain the benefits of a forward model—the benefit of being ready for the sensory consequences so that the motor system can implement a correction right at the instant when it is needed, without a delay.

The goal:
The motor system:
The concept:

Back 26

“The perfect hot shower” AN ANALOGY to help to explain the benefits of a forward model—the benefit of being ready for the sensory consequences so that the motor system can implement a correction right at the instant when it is needed, without a delay.

The goal: a perfect hot shower at just the right temperature.
The motor system: turning the water faucet to get more or less hot water.
The concept: Do you know how much to turn the faucet to get the change in the water temperature you want?
What a forward model does for you—you know what to expect from the turn of the water faucet and when to expect it.

Therefore, in your home shower, if the expected change in water temperature doesn’t occur when it should, you can then implement the next turn on the faucet that will get the change in water temperature you want.

If your movement is not generating the right feedback at the right time, your nervous system is ready to adjust the motor commands to ensure that you achieve the goal.

Front 27

8.3 Question: What do we do to fix a mistake during the motion?

Back 27

Answer: Feedback reactions/Reactive motor control using different strategies distributed across the neuraxis (spinal cord, brainstem, cortex).

Implemented by motor regions that receive sensory afference during the movement.

The motor regions and the entire neuraxis is tuned and ready to listen for the sensory afference in order to achieve the goal of the movement.

Front 28

REACTIVE CONTROL:

Back 28

REACTIVE CONTROL: Rapid/immediate responses to unexpected perturbations during the movement execution. Corrections occur due to info from ongoing peripheral feedback during the movement—“responses to the unexpected”
WHOA!! Something is not right here!

Front 29

UNEXPECTED PERTURBATIONS: Can be due to 1)
or 2)

Back 29

something external to you—unanticipated, surprising

Something during the motion such as: You are bumped—something “hits”you, someone opens a door in your path, something moves your arm as you reach in, you’re bumped into when standing or walking
Something happens to the environment during the motion: it changes in some way—the surface you are on moves, the target of your motion moves before you get there, an obstacle rolling out into the pathway
External Unexpected Perturbation Examples related to different volitional movement:
reach to grasp- hand gets bumped, object gets moved
locomotion -foot lands on a rock, someone comes around the corner
postural control/balance - someone bumps into you, rug is pulled out from underneath you

or could be due to 2) your movement plan not being an accurate anticipation of the situation, inaccurate internal model.
Bad Planning/inaccurate movement plan:
Milk is too light, obstacle is taller or further away, surface is more slippery, unstable...

Front 30

What are the reactive corrections we see during movement?

Back 30

What are the reactive corrections we see during movement?
Short loop (M1) and Long Loop (M2) reflexes-increase in motor activity in the active muscle groups

Triggered reactions/automatic corrections (M3)-balance responses, stumble/slip, wineglass complex, multiple joint responses.

Reaction time (M4)-Voluntary correction to do whatever it takes to save the goal of the movement

Front 31

What are the sources of peripheral feedback that drive these corrections—the provide ongoing peripheral feedback during the movement?

Back 31

What are the sources of peripheral feedback that drive these corrections—the provide ongoing peripheral feedback during the movement?
Somatosensation
Vision
Vestibular
Auditory

Front 32

FEEDBACK MOTOR CONTROL:

Back 32

FEEDBACK MOTOR CONTROL: Trying to get it right the first time: react to unexpected events during the movementWHOA! The milk… it’s too light!
Try to implement a way to achieve the original goal of the movement. The movement you see may look different from what was originally planned—the focus is the goal of the movement!

Front 33

M1, M2, M3 & M4
Response type:
Loop time (ms):
Structures involved:
Modified by instructions:
Affected by number of choices:

Back 33

M1
Response type: myotatic reflexes (autogenic)
Loop time (ms): 30-50
Structures involved: muscle spindle, gamma, same muscle
Modified by instructions: no
Affected by number of choices: no

M2
Response type: long loop reflexes (autogenic)
Loop time (ms): 50-80
Structures involved: spindles, cortex or cerebellum, same muscles
Modified by instructions: yes
Affected by number of choices: no

M3
Response type: triggered reactions (not autogenic)
Loop time (ms): 80-120
Structures involved: various receptors, higher centers, and associated musculature
Modified by instructions: yes
Affected by number of choices: yes

M4
Response type: reaction time (not autogenic)
Loop time (ms): 120-180
Structures involved: various receptors, higher centers, any musculature
Modified by instructions: yes
Affected by number of choices: yes

Front 34

M1:

Back 34

M1: Short latency spinal stretch reflex force corrections—within the muscle where the original somatosensory stimulus was detected. Can be stimulated by proprioceptive and cutaneous inputs and the force change occurs within 30-50msec of the perturbation. (see first red line below—all the muscles have a burst of activity due to the motion of the arm after the ball hits)

Front 35

M2:

Back 35

M2: Long latency supraspinal force corrections 50-80msec after the perturbation. Muscle activity in a task-specific manner across the extremity—takes into account the arm posture. (see second red line and note the differences in muscle activation.

Front 36

M3 Triggered reactions/automatic responses

Back 36

Task specific multi-segmental responses functional responses to unexpected perturbations that will change the appearance of the ongoing movement in order to achieve the goal of the movement. Organized at a brainstem level. Stereotypical (meaning we call do them).

Reach to Grasp goal: visuomotor responses mediated by visual input (and even auditory input) about the result of the movement to attempt to change trajectory

Manipulation goal: Triggered reactions from somatosensory input like slip due to inadequate grip such as the wineglass effect, or not throwing the object due to too much load force.

Postural Control/Balance: automatic postural responses including ankle, hip, stepping strategy, righting reactions.

Locomotion: transport the body from point a to point b while maintaining continuous progression, balance, and match to the environment—so see stumble and slip responses that prevent a fall and allow you to keep going.

Front 37

Question 8.4 What do we do to change the next motion? Get right the next time?
Relationship between feedback during this movement and feedforward information from the next movement:

Back 37

Question 8.4 What do we do to change the next motion? Get right the next time?
Relationship between feedback during this movement and feedforward information from the next movement: update the internal model.
A mismatch between the predicted and actual sensory outcomes (prediction error) may then trigger force corrections (feedback reaction) along with updating the relevant internal models which becomes part of the feedforward information used for planning the next motion.

The cerebellum sends continuous updates during and after the motion to provide the error signal used to provide the corrections necessary to compensate for the perturbations—a motion update signal.

Who gets this CB information and changes? The output targets for the cerebellum —braintstem and cortex (via thalamus).

Additonally all of the regions that receive sensory afference directly and use it to implement corrections —spinal cord, brainstem, cortex.

Front 38

Predictive control/Adaptive Control after the movement:

Back 38

Predictive control/Adaptive Control after the movement: before the movement occurs, “plan to use for the expected” feedforward portion of the movement planned in advance using previous information and current status. Those regions that received the inputs during the motion will adjust to be ready for the next motion.

Attributes: Gradual change that occurs with immediate repetition of the skill—Adaptive because it is the next one you are doing, not the current one. Address a mismatch—change the motor plan. If the situation changes, you have to undo what you have changed/adapted to. So these are not perturbations, these are “changes in the rules of the game” “new expectations for movement”

Front 39

Examples of mismatches from your plan to what actually happened:

Back 39

Examples of mismatches from your plan to what actually happened:

Reach to Grasp/throw: what you goal coordinated did not end up being where you landed, you missed.
 
Manipulation: what you expected to feel does not match with what you felt—too heavy/too light, too slick
 
Locomotion: Surface changes while walking on it—speed, uneven, tilted, slick
 
Postural Control/Balance: world is dark, tilted, uneven or fast or slick.

Front 40

Learning to predict: is one error equivalent to another?

Back 40

Cerebellar learning is thought to depend largely on error feedback. Activation in the cerebellum is increased during difficult movements, which results in more error feedback. For error feedback to be useful in predictive control, errors from past movements must be used to update subsequent movements. Diedrichsen studied reaching movements where random errors were induced in 1 of 3 ways: by mechanically perturbing the hand, by perturbing the visual feedback provided by a cursor representing the hand, or by moving the target. The first two were considered motor ‘execution’errors because the subject would associate them with their movement, whereas the ‘target’ error would be attributed to some external influence. Subjects made online corrections for all error types, but made feedforward corrections of the next reach only after execution errors, not target.
Brain doesnt process all errors the same: only errors assigned to the movement lead to feedforward correction on the next movement.

Front 41

New movements next time that better match the task—and allow you to “relax” into the task with the Ok, I get it now, this is OK, off we go:

Back 41

New movements next time that better match the task—and allow you to “relax” into the task with the Ok, I get it now, this is OK, off we go:

Adjust reach to grasp for more accuracy or for easier catching
Adjust grip/load forces to handle object
Adjust phasing of steps, timing of motions during gait
Adjust postural responses so that they are scaled to the situation give you the upright.

Front 42

PRECONTACT PHASE—REACH TO GRASP—

1. GOALS OF MOVEMENT:

Back 42

PRECONTACT PHASE—REACH TO GRASP—external drive per object location and size/shape, assessed visually—Visuomotor transformation

1. GOALS OF MOVEMENT: GET THE HAND IN THE RIGHT PLACE AT THE RIGHT TIME AND IN THE RIGHT CONFIGURATION TO PICK UP THE OBJECT.

Front 43

PRECONTACT PHASE—REACH TO GRASP—
2. MOVEMENT SET: observable movements

Back 43

2. MOVEMENT SET: observable movements

UE Reach movement: Trajectory of the upper extremity based upon object location relative to the hand. Speed of motion also influenced by what you will do with the object (hit it, touch it, grasp it)

Hand Grasp: shape of the hand based upon the shape/size of the object and it’s intended use after grasp
**Also depends upon memory of intrinsic object properties that can only be determined by touch—texture, weight, etc. As well as knowledge about the object from ventral pathway. See next slide.

Visuomotor transformation: These visual attributes become “goal coordinates” for the movements and are set by the posterior parietal cortex/area 5,7

Front 44

Externally Driven/Visuomotor Transformation

Skilled motor behavior relies on accurate

Those models generate the motor plan—which includes the

Back 44

Externally Driven/Visuomotor Transformation

Skilled motor behavior relies on accurate internal models of both our own body and objects we interact with provided by anticipatory feed-forward motor control and past experience. The internal models are not fixed entities but learned and updated with motor experience—they improve with practice.

Those models generate the motor plan—which includes the sensory expectations about the movement which allow the next phase of each movement to continue. (see Motor Control 1 concepts).

Front 45

EXTERNALLY DRIVEN: Visuomotor transformation—

Back 45

EXTERNALLY DRIVEN: Visuomotor transformation—planning motions to meet constraints imposed by external stimuli.
This planning processes translates an object location and an object size and shape into a series of motor actions that allow you to reach out and grasp it.

It is also involved in stepping over an object—translate the location of the obstacle, the size of the obstacle into a series of motor actions that allow you to move your leg to step over it.

Front 46

External drive: Reach and Grasp POSTERIOR PARIETAL CORTEX AND PREMOTOR CORTEX.
Object properties:

Back 46

Object properties: external obtained by vision - location, size, shape

Reach: where is the object—direction/distance

Grasp: size, shape of the object.

Combined with the intended action with the object.

Front 47

Relationship between cortical planning areas and the BG and CB.

Back 47

The lateral zone of the cerebellar hemisphere participates in the planning and programming of movements by integrating sensory info.
It receives info from the sensory association cortex, which also sends info to the basal ganglia and premotor cortical areas.
The premotor cortical areas receive inputs from the basal ganglia, sensory AC, and lateral zone of cerebellum and project to the motor cortex and the intermediate zone of the cerebellum (efference copy, I believe). The intermediate zone of the cerebellar hemisphere contributes to movement execution by monitoring actual sensory feedback and processing error signals that compensate for prediction errors in movement planning.

Front 48

POSTCONTACT PHASE—GRIP/LOAD—LIFT/MANIPULATE—LOWER/RELEASE—internal drive per memory of the object
Sensorimotor transformation PPC, BG and SMA

1. GOALS OF MOVEMENT:

Back 48

1. GOALS OF MOVEMENT: PICK UP THE OBJECT WITH THE RIGHT AMOUNT OF FORCE TO NOT DROP OR TO NOT CRUSH

Front 49

MOVEMENT SET:

In hand manipulation: grip and lift forces precisely are matched to

Back 49

MOVEMENT SET:

In hand manipulation: grip and lift forces precisely are matched to the intrinsic object properties of texture and weight—based upon previous experience with that object. This information is part of the motor plan. The cerebellum, basal ganglia, parietal cortex, and S1/M1 all contribute to planning this goal per its complexity. See slide with fMRI brain images.

Front 50

The sensory information (sensory expectations) contained in the instantaneous motor plans can be considered to be

Back 50

The sensory information (sensory expectations) contained in the instantaneous motor plans can be considered to be forward models of expected sensory information associated with prior successful motor acts. It usually only takes 1 to 3 lifts of an unfamiliar object to create accurate forces to that object. During repetitive lifting, random changes in weight cause us to scale our grip force according to the previous lift—for example repetitive sips out of your diet coke can. Grip force is determined in a predictive manner to match precisely the load force to be experienced when lifting a familiar object. Importantly, these memories transfer between hands—pick it up once with your right hand, the next lift with left hand will incorporate what the right hand learned.

Front 51

Internally Driven/Sensorimotor Transformation

RECALL: Skilled motor behavior relies on accurate predictive models of both

Back 51

our own body and objects we interact with provided by anticipatory feed-forward motor control. Those models are part of the motor plan—they form the sensory expectations about the movement and allow the next phase of each movement to continue.

The models are not fixed entities but learned and updated with motor experience—they improve with practice.

Front 52

INTERNALLY DRIVEN Sensorimotor transformation—planning motions to match the physical properties of an object like

Back 52

INTERNALLY DRIVEN Sensorimotor transformation—planning motions to match the physical properties of an object like weight, texture, temperature, surface compliance (properties that can’t be seen very easily, but that can be felt by touch); detect using the somatosensation system a series of mechanical events that make transitions between consecutive action phases of task to meet the overall goal. With in hand manipulation of an object or bimanual task like typing or whole body movement like dancing or tumbling—sequence of specific sensory events to indicate that the movement/task is progressing along.

Front 53

Functional Role of the Supplementary and Pre-supplementary motor areas
SMA

Back 53

External stimulation of SMA produces complex sequences of motions including activation of multiple postural groups, lower extremity movements, and bilateral sequences of motions with the upper extremities (playing the piano) that are independent of an external target.
SMA is more active during self-initiated movement that do not rely on cues from external signals (i.e., visual or auditory). Involved in the planning of internally generated motions.
Work closely with the BG for planning/controlling complex volitional movement sequences—initiation, termination, what is next in the sequence.
Involved in the learning and retention of movement sequences.

Front 54

CORRECTIONS IMPLEMENTED DURING MANIPULATION—WHEN WHAT WAS PREDICTED DOES NOT OCCUR. HOW WE SAVE THE GOAL OF THE MOTION.

Back 54

Data from experiment where people lifted a 200g object they thought was going to be 800g.
Fast-adapting type II afferents signal lift-off before the predicted time, which triggers a corrective action that kicks in after ~100ms delay. So, the object is lifted higher than planned.
Mismatch between actual and predicted weights activates the posterior parietal cortex regardless of whether the weight is too heavy or too light.
With the load-phase controller targeted for a heavier weight (as in 200g example), the corrective action correlates with increased neural activity of the cerebellum, whereas there is increased activity in the primary sensorimotor cortex if the controller is targeted for a lower weight.

Front 55

GOALS OF POSTURAL CONTROL MOVEMENTS:

Back 55

GOALS OF POSTURAL CONTROL MOVEMENTS:

Maintain ongoing balance/steadiness of the body relative to gravity during the task/goal directed motion—COM in BOS.

2. Maintain postural and visual orientation of body to itself and relative to the task, environmental constraints, and sensory inputs–POSTURAL ALIGNMENT & GAZE STABILIZATION

3. Readiness to move—POSTURAL TONE

Front 56

TASK SPECIFICITY OF POSTURAL CONTROL—although postural control is often implemented with stereotypical postural responses elicited by different perturbations, these movements are modulated by

Example 1: Locomotion

Back 56

TASK SPECIFICITY OF POSTURAL CONTROL—although postural control is often implemented with stereotypical postural responses elicited by different perturbations, these movements are modulated by the ongoing tasks—the current goal of the movement or position of the person.

Therefore, postural control will have different specific goals based upon the actual context and goal of the motion:

Example 1: Locomotion
Running to catch a ball - visually orient and align body to keep eye on the ball, not on the ground
Running on a trail - visually orient to keep eye on the ground to watch for obstacles

Front 57

TASK SPECIFICITY OF POSTURAL CONTROL
Example 2: Sitting posture alignment of pelvis, lumbar spine, head/neck in order to:

Back 57

Example 2: Sitting posture alignment of pelvis, lumbar spine, head/neck in order to:
to position the eyes to see what you are reading tilt head neck to align eyes over paper, forward head to bring eyes closer to screen, slump/slouch to bring head lower to align with computer screen
to position the upper extremities to hold book, rest on the desk write things or to use the key boardslump or slouch to rest arms on desk.

Front 58

CHALLENGES TO THE POSTURAL CONTROL SYSTEM: PERTURBATIONS
GOAL 1: MAINTAIN COM IN BOS

VOLITIONAL PERTURBATIONS

Back 58

VOLITIONAL PERTURBATIONS based upon internal predictions of how the movement set as part of a motor plan will disturb balance and orientation. In other words, anticipating the effect of the reach, the step, the lean forward to look over the edge in order to make sure that your COM stays stable in the BOS.
Anticipatory postural and alignment adjustments— Postural Set part of the Motor Plan
FEEDFORWARD

Front 59

CHALLENGES TO THE POSTURAL CONTROL SYSTEM: PERTURBATIONS
GOAL 1: MAINTAIN COM IN BOS
EXTERNAL PERTURBATIONS

Back 59

EXTERNAL PERTURBATIONS caused by something unexpected, unplanned bumping into you, by the ground/surface shifting, the object you are reaching for or stepping on moving suddenly, or even when the visual background moves when you are stable.
Reactive postural adjustments/responses and Volitional Postural Corrections
FEEDBACK

Front 60

CATEGORIES OF MOVEMENTS THAT MAINTAIN BALANCE/POSTURAL CONTROL & RESTORE IT: GOAL 1

FEEDFORWARD Anticipatory Postural Adjustments: occur before an expected perturbation to ensure COM will stay over the BOS.

Precisely timed compensatory action to offset the anticipated perturbation to balance/stability that will be caused by the movement set.

This is the POSTURAL SET component that accompanies the movement set of any volitional motor plan. Sensory afference used to create the overall motor plan.

Examples:

Back 60

Trunk control/core stability required to hold yourself stable when lifting a heavy object/patient with your extremities. (Not falling over when reaching overhead with both upper extremities. Consider the SCI client with no trunk innervation…what happens when he reaches over head?)

Weight shifts prior to movements like reach/grasp or to the stance foot in gait. Stand in front of the projector lamp and face the screen—watch your shadow as you pick up one leg. Try marching and watch the sequence of weight shifts and leg movements.

“The central command for a voluntary limb movement is associated with a simultaneous feedforward command anticipating an expected postural perturbation.”

Front 61

FEEDBACK Automatic Postural Responses: maintain and/or restore the COM within the BOS to an unexpected perturbation

Stereotypical responses (everyone does them) that are matched in amplitude/amount (tap vs. shove) and direction to the stimulus that elicit them. (forward/ backward/ sideways).

Occur in response to

Back 61

an unexpected stimulus/perturbations –reactive.

Perturbations detected by incoming sensory afference: vestibular, visual, somatosensory

These are BALANCE REACTIONS (M3)

Automatic Postural Responses ANKLE STRATEGY, HIP STRATEGY, STEP STRATEGY, SUSPENSORY STRATEGY.
Righting reactions

“Postural adjustments to unexpected disturbances depend upon feedback…” they can be relatively simple and fast, like a quick stretch reflex, but usually they are the product of complete motor reactions that are innate, stereotypical and released as a whole.

 Even though they are automatic and predictable, these responses are modifiable or tuned to the volitional movement goal/intention—FEEDFORWARD BIASING TO VOLITIONAL MOVEMENT GOAL. The reading reference calls this “central set”

Front 62

FEEDBACK MOTOR CONTROL: 4 levels of responses in Postural Control/Balance

Back 62

FEEDBACK MOTOR CONTROL: 4 levels of responses in Postural Control/Balance
M1: short loop increase muscle activity in muscles activated by stretch with perturbation
M2: long loop
M3: automatic reactions—the balance strategies.
M4: voltional reaction time responses (learned reactions or a last ditch volitonal effort to stay upright.

Front 63

FEEDBACK M4 Volitional Postural Corrections: In other motor acts new reactions can be learned—for example when a football player or judo student learns how to roll when she falls rather than reach out with her arms to catch herself. Reaching out is an automatic indwelling response—and is initiated faster and reliably—whereas rolling is

Back 63

FEEDBACK M4 Volitional Postural Corrections: In other motor acts new reactions can be learned—for example when a football player or judo student learns how to roll when she falls rather than reach out with her arms to catch herself. Reaching out is an automatic indwelling response—and is initiated faster and reliably—whereas rolling is a newly learned motor behavior.

Must consciously override the automatic response with an alternative volitional response.

Volitional—so that means they improve with practice.

For example: Balance control in learning to ride a bike—becomes an automatic response

Also referred to as “reaction time” response.

Front 64

MOVEMENTS THAT MAINTAIN POSTURAL ALIGNMENT AND GAZE STABILIZATION: GOAL 2

Automatic Postural Alignment Reflexes:

Back 64

MOVEMENTS THAT MAINTAIN POSTURAL ALIGNMENT AND GAZE STABILIZATION: GOAL 2

Automatic Postural Alignment Reflexes: maintain postural orientation of eyes, head and body to vertical:

Reflexes are “tuned” to the context of ongoing volitional movement or position--FEEDFORWARD BIASING. Or “central set”

Can be incorporated into postural set to assist in volitional movement production—therefore one of the motor programs (ingredient) executed as part of an anticipatory motor plan.

But because they are also elicited by vestibular, visual and somatosensory inputs they can also be considered reactive or a FEEDBACK elicited response.

Front 65

Gaze Stabilization:

Back 65

Gaze Stabilization:
VOR: Vestibular Ocular Reflexadjust eye position to maintain visual focus when head moves

Front 66

Postural Alignment reflexes:

Back 66

Postural Alignment:
VSR: Vestibular Spinal Reflexescoordinate head and neck motions with the trunk and body in order to maintain the head and eyes in an upright/vertical position.

Righting reactions—visual and vestibular orient head to vertical on the body (ex: supine to sit) body on body, head on body.

VCR: Vestibulocollic reflexes—assists with stabilization of the head in space by activation of the neck muscles during head motion. Provides compensatory head/neck motions when the body is moving when it is necessary to maintain head position.

Front 67

MOVEMENTS/PRESENTATION OF POSTURAL TONE—regulation of muscle tone GOAL 3

Back 67

MOVEMENTS/PRESENTATION OF POSTURAL TONE—regulation of muscle tone GOAL 3


Anticipatory Postural tone—readiness to move by maintaining sufficient activation of the anti-gravity muscles. Requires intregration of sensory inputs and central set (task specific demands).
In standing or sitting up-right see increased activity in the antigravity trunk and lower extremity muscles.


Tonic Neck Reflexes—head moves and extremities respond with increase in postural tone—vestibular and neck proprioceptors activated
Assymetrical: ATNR—turn head to right, right limbs extend, left limb flex
Symmetrical: STNR—head down UE’s flex, LE’s extend (standing). Head up UE’s extend and LE’s flex (crawling)

Front 68

Visual inputs provide information about orientation to vertical/the horizon. While vision can detect motion, it can’t

Back 68

Visual inputs provide information about orientation to vertical/the horizon. While vision can detect motion, it can’t distinguish between movement made by you vs. movement made by the environment around you. SS and vestibular inputs are used for this. NEEDED FOR ANTICIPATORY POSTURAL CONTROL—PLANNING MOVEMENTS AND THE ASSOCIATED POSTURAL SET NEEDED TO MAINTAIN STABILITY.

Front 69

Vestibular inputs provide information about the body relationship to gravity which determines how much the body is tilted with respect to gravity as well as the direction of the sway—forward/backward/side to side. NEEDED FOR

Back 69

Vestibular inputs provide information about the body relationship to gravity which determines how much the body is tilted with respect to gravity as well as the direction of the sway—forward/backward/side to side. NEEDED FOR THE DIRECTIONAL ACCURACY OF THE BALANCE RESPONSES. (see below for difference between sliding surface and tilting surface.
Also provides rotational info about head motions relative to body motions—are you turning in space or being turned? Are you moving or is the world moving around you?

Front 70

Cutaneous and proprioceptive afferent information detect

Back 70

Cutaneous and proprioceptive afferent information detect
contact with the BOS (feet on the ground, bum on the chair, finger tip touch on a surface) and
position/motion of the body relative to itself like what occurs with postural sway in static stand or motion of the body.
NEEDED FOR CORRECT TIMING OF BALANCE RESPONSES.
SS Can’t distinguish between changes in muscle length that would occur from linear translation of a surface (forward/backward) from tilts of the surface (upwards/downwards). The two motions cause the same stretch to the gastroc; however a different balance response is needed to stay upright. When the surface moves backward—need to activate the PF to restore alignment. When the surface tilts backwards—don’t want the PF to be active or you’ll fall. Need to use dorsiflexors. The vestibular system is necessary to make this change in response.

Front 71

MOTOR SYSTEMS EXECUTING MOVEMENTS OF POSTURAL CONTROL:

Vestibular Nuclei
Lateral Vestibulospinal Tract from LVN:

Medial Vestibulospinal Tract from MVN:

PPN and Reticular Formation structures


MLF-

Back 71

MOTOR SYSTEMS EXECUTING MOVEMENTS OF POSTURAL CONTROL:

Vestibular Nuclei
Lateral Vestibulospinal Tract from LVN: projects to thoracolumbar cord for postural changes to compensate for tilts and movements of the body, activate antigravity muscles.

Medial Vestibulospinal Tract from MVN: projects to cervical cord, adjust head position to upright, stabilizes the head system while walking.

Use spinal interneurons synergies to activate muscles involved in the response: This means that the same postural response syngeries, righting reactions, VSR’s etc. can be used by and will be seen in both anticipatory postural set and reactive postural responses. i.e. the same ingredients can be used to make different recipes
synergy: ”functional coupling of groups of muscles constrained to act together as a unit”

PPN and Reticular Formation structures
Lateral and Medial Reticulospinal Tracts

MLF-connects VN to ocular nucleii, spinal accessory, and superior colliculus

Front 72

“A unique feature of the vestibular system is that many second-order sensory neurons in the brain stem are also

Back 72

“A unique feature of the vestibular system is that many second-order sensory neurons in the brain stem are also premotor neurons; the same neurons that receive afferent inputs send direct projections to motoneurons.

An advantage of this streamlined circuitry is that vestibular sensorimotor responses have extraordinarily short latencies. For example, the latency of the vestibulo-ocular reflex (VOR) is as short as 5–6 ms. Simple pathways also mediate the vestibulo-spinal reflexes that are important for maintaining posture and balance.”
This makes for very fast responses!

Front 73

Distributed control of Postural Control

different areas responsible

Back 73

Distributed control of Postural Control

Spinal cord and brainstem effector sites: synergies, automatic responses

Cerebellar for adaptation to environment and task demands based on past experience.

Basal Ganglia circuits for automaticity in response selections to meet task goals and regulation of postural tone

Cortical modulation for goal and context—anticipatory control! Implement Volitional responses

Front 74

POSTURAL RESPONSES—if anticipatory postural set prevents loss of balance, postural reactions are used to recover balance from an unexpected perturbation such as a stumble, slip, trip, push, pull, or drop.

e.g. Short latency muscle activation—

Back 74

Short latency muscle activation—spinal cord stretch reflex loop, segmental reflex

Postural responses—activation of muscle synergies across the entire body to counteract the perturbation force and restore balance. Context specific expression, adaptable

Medium latency muscle activation—brainstem reflex loop elicitng organized postural responses

Long latency muscle activation late phase—motor cortex loop as response goes on and modulates the brainstem circuits.

Voluntary reaction time muscle activation—cortical reflex loop

The longer the latency—or time it takes for the response to be seen—the more complex and the more potential for cortical involvement in the response and the more potential for cortical modifiability of the postural response with practice (i.e. catch and roll vs. reaching out)

Front 75

Postural tone/control:
Inhibitory output from
Excitatory output from

Back 75

Postural tone/control:
Inhibitory output from BG loop to PPN—which inhibits the reticulopsinal system.
Excitatory output from cortex to PPN

Front 76

POSTURAL TONE—regulation of muscle tone GOAL 3


Cerebellar regulation of postural tone:
Basal Ganglia regulation of postural tone:

Back 76

POSTURAL TONE—regulation of muscle tone GOAL 3


Cerebellar regulation of postural tone: outputs from the anterior lobe facilitates activity in the Lateral Vestibular Nucleus. The Lateral Vestibular Nucleus projects to gamma motorneurons setting the spindle sensitivity to stretch. Cerebellar system regulates the gain of the spindle settings. Damage to the anterior lobe is associated with hypotonia.

Basal Ganglia regulation of postural tone: via SNPr outputs to the PPN influencing the activation of the MRST and reticular activating system descending pathways.

Front 77

Even though balance responses are organized and implemented by subcortical structures in the brainstem and spinal cord, there are cortical influences on postural responses:

Back 77

Intention of movement—tunes reactions to meet overall task goal through cortical loops with BG its outputs to cortex & BS regions.
Context— initial starting context for movement will influence balance response initiated thru loops w/ cerebellum & outputs to cortex & BS regions.
Changes w/ past experience—modifiable over time & w/ practice—as movement in which response is often elicited is learned—using cerebellar & BG learning mechanisms.
Balance responses differ based on cognitive load/dual task. If attention is divided btw a motor & cognitive task, balance responses will be less accurate & effective than when completing the motor task alone. This depends on the type of motor task & cognitive task. Changes are seen esp. in later stages of the balance response— medium & long llatency responses will be affected not the short latency.
Prior intention/thought/conscious volition to choose to respond in a specific way to perturbation will override any auto response. (rolling, not FOOSH

Front 78

goal of gait: transport the body from point a to point b while maintaining:

Back 78

goal of gait: transport the body from point a to point b while maintaining:
1. AUTOMATICITY
2. POSTURAL CONTROL
Anticipatory & reactive
3. ANTICIPATORY FEEDFORWARD CONTROL—external & internal driven goal directed locomotion

Front 79

Neural control of automaticity
Sensory afference as the source of CONTROL for locomotion and standing:

Back 79

Sensory afference as the source of CONTROL for locomotion and standing: training stimulus

The specific details of the motions in the task of gait are carried out with the information provided by continuous inputs of the kinematics and kinetics of the trunk and lower extremities.

Afferents activated by load, speed, direction:
Proprioception and cutaneous inputs about load and kinematics/kinetics of speed
contact with the surface or objects

Front 80

Neural control of automaticity
Stimulation of the MLR

Back 80

Stimulation of the MLR
Changes the responsiveness of the spinal cord to sensory inputs.
Increases the speed of locomotion.

Front 81

Neural control of automaticity
“State dependence”

Back 81

“State dependence” the spinal cord circuitry responds to a given stimulus differently under different conditions or “states.”

Phase Dependent response to afferent inputs: stance vs. swing

Modulatory control: determines which sensory inputs can be used to drive activity in response to sensory afference. Sets up the capacity for task specificity.

Front 82

“What do we mean when we say the spinal cord is smart?

Back 82

We use the term here to emphasize that the spinal cord can process sensory information in the context of the combination of events occurring at a given time. We often refer to this as state-dependent processing, reflecting an ability to “decide” how to respond to a given sensory input.

For example, a given pattern of sensory input can be processed (interpreted) so that ipsilateral flexion and contralateral extension can be generated in the hindlimbs when the dorsal surface of the foot is mechanically perturbed during the swing phase of a step. However, if the same stimulation is applied during the stance phase of that same limb, then an ipsilateral extensor and contralateral flexor will be induced. The spinal cord interprets the stimulus differently, depending on the phase of the step. This is an example of a useful “decision-making” capacity.

Front 83

Both of these responses seem like positive adaptive events to assure that stepping continues with minimal disruption. A number of other examples exist in animals and in humans that illustrate that the spinal cord responds to proprioceptive input in a “state-dependent” manner. One of the more functional illustrations of this is when

Back 83

Both of these responses seem like positive adaptive events to assure that stepping continues with minimal disruption. A number of other examples exist in animals and in humans that illustrate that the spinal cord responds to proprioceptive input in a “state-dependent” manner. One of the more functional illustrations of this is when the level of load on the limbs during stepping is altered. For example, in individuals with complete SCI, the level of activation of extensor muscles increases as the level of load bearing increases. A similar response to loading was observed in nondisabled and incomplete SCI subjects. In most cases, these responses to loading intuitively seem “teleologically correct,” in the sense that it would seem to be an advantage for the response to loading to be automatic or programmed into lower “circuits.”

From: Spinal Cord Medicine, Principles and Practice 2003. Edgerton, Harkema, Dobkin.

Front 84

CPG function with somatosensation:
a critical feature of central pattern generators is their ability to

Back 84

CPG function with somatosensation:
a critical feature of central pattern generators is their ability to receive, interpret, and process sensory information that can in turn generate the appropriate motor output.

Right Terminal Stance/Terminal hip extension—STRETCH
Lengthen hip flexors activates the muscle spindle Ia afferents.
Activate R hip flexors
Inhibit R hip extensors

Left Initial Contact—
LOAD
Body weight activates GTO Ib & muscle spindle Ia afferents
Inhibit L Flexors, activate L extensors

Front 85

There are separate functional CPG networks controlling

Each CPG in the circle can be modified and continued by

Back 85

There are separate functional CPG networks controlling forward and backward walking in humans, and separate networks controlling the right leg and the left leg.

Each CPG in the circle can be modified and continued by peripheral sensory input and descending supraspinal inputs.

Front 86

Mesencephalic locomotor region
definition from text

Back 86

a brain stem nucleus below the inferior colliculus that evokes locomotion in the decerebrate cat when electrically stimulated

Front 87

CPG’s recruit synergies:

Back 87

CPG’s recruit synergies:
The CPG (like other descending inputs) synapse upon networks of interneurons that activate a combination of alpha motorneurons creating muscle synergies. The recruitment is task dependent.
The synergies not only specify which group of muscles fire together but also the timing of the firing of each individual muscle in the synergy. So which muscles, the sequence and on/off=spatiotemporal activation

Front 88

A simple inspection of the maps suggests that almost all of the EMG activity during locomotion can be represented by five

Back 88

A simple inspection of the maps suggests that almost all of the EMG activity during locomotion can be represented by five separate periods of MN activation. The timing of these activity peaks tends to be associated
with the major kinematic and kinetic events in the gait cycle, namely
(see Fig. 1, bottom):
weight acceptance (1)
loading/propulsion (2)
trunk-stabilization activity during the double support phase (3)
liftoff (4)
heel strike (5)

Thus, it appears that the activation patterns may represent the drive provided by spinal pattern generators and/or sensory feedback.”

Front 89

3 general principles that have emerged from the study of spinalized cats

Back 89

1. Body-weight supported treadmill training improves the ability of the lumbo-sacral spinal cord to generate weight-bearing stepping
2. patterns of sensory input during locomotor training are critical for driving the plasticity that mediates locomotor recovery
3. Pharmocological treatments can be used to excite the spinal neurons that generate stepping

Front 90

C7-T1 ASIA B paraplegia. No voluntary motor function in the trunk or LE’s. Injured July 2006.

Oct 2007-Nov 2008 participated in 170 locomotor training sessions.
54 hours stand training
108 hours step training
C7-T1 ASIA B paraplegia. No voluntary motor function in the trunk or LE’s. Injured July 2006.
Oct 2007-Nov 2008 participated in 170 locomotor training sessions.
54 hours stand training
108 hours step training
TMS over motor cortex elicits no MEP response in the LE’s
SEP’s recorded in the cortex from LE sensory stim—delayed.
Dec 2009 epidural electrode implantation over spinal cord segment L1-S1 at T11-L1 vertebral levels.
Resumed locomotor training sessions. Epidural stim set for optimum support of standing (sustainable coactivation of bilateral LE muscles) and stepping (rhythmic activity of alternating flexion/extension between right/left leg).
Ave. of 54 minutes of epidural stim per training session. Training session up to 4 hours.
OUTCOMES - sit to stand & standing

Back 90

Standing:
“Epidural stim of caudal segments (L5–S1) of the SC combined w/ sensory information related to bilateral extension & loading was sufficient to generate standing w/o manual facilitation when 1st attempted w/ 65% BW support. Patient was able to stand w/o manual facilitation while the amount of BW support was progressively reduced to full weight bearing.”
Sit to Stand:
“Transitioning from sit to stand w/o bodyweight support altered EMG activity during
epidural stimulation even though the stimulation parameters remained constant. When loading was initiated, EMG activity increased & was sufficient to support the patient’s bodyweight with minimum assistance needed from the trainers. Once the patient was standing, there was greater contraction of flexors & extensors & proximal & distal muscles than when patient was in transition from sitting to standing."

Front 91

C7-T1 ASIA B paraplegia. No voluntary motor function in the trunk or LE’s. Injured July 2006.
Oct 2007-Nov 2008 participated in 170 locomotor training sessions.
54 hours stand training
108 hours step training
TMS over motor cortex elicits no MEP response in the LE’s
SEP’s recorded in the cortex from LE sensory stim—delayed.
Dec 2009 epidural electrode implantation over spinal cord segment L1-S1 at T11-L1 vertebral levels.
Resumed locomotor training sessions. Epidural stim set for optimum support of standing (sustainable coactivation of bilateral LE muscles) and stepping (rhythmic activity of alternating flexion/extension between right/left leg).
Ave. of 54 minutes of epidural stim per training session. Training session up to 4 hours.
OUTCOMES - postural responses in standing
and Stepping

Back 91

3. Postural responses in standing:
“When the patient received epidural stimulation and intermittent manual facilitation during standing,
postural responses occurred in leg EMG activity when he shifted his centre of gravity sagittally.”

After 80 sessions (webvideo 3), the patient could start and maintain continuous full weight-bearing standing without manual facilitation (maximum 4·25 min) with bilateral tonic EMG activity (figure 4; webvideo 3).
Stepping
Epidural stimulation at 30–40 Hz and task-specific sensory cues were needed to generate locomotor-like patterns. Sensory cues for manually facilitated stepping included load alternation and leg positioning with appropriate kinematics of the hips, knees, and ankles timed to the step cycle. The EMG activity in the legs was markedly different depending on the loading and kinematic patterns when using identical stimulation parameters. Consistent oscillatory EMG patterns did not occur when the legs were extended and bilaterally loaded but

Front 92

C7-T1 ASIA B paraplegia. No voluntary motor function in the trunk or LE’s. Injured July 2006.
Oct 2007-Nov 2008 participated in 170 locomotor training sessions.
54 hours stand training
108 hours step training
TMS over motor cortex elicits no MEP response in the LE’s
SEP’s recorded in the cortex from LE sensory stim—delayed.
Dec 2009 epidural electrode implantation over spinal cord segment L1-S1 at T11-L1 vertebral levels.
Resumed locomotor training sessions. Epidural stim set for optimum support of standing (sustainable coactivation of bilateral LE muscles) and stepping (rhythmic activity of alternating flexion/extension between right/left leg).
Ave. of 54 minutes of epidural stim per training session. Training session up to 4 hours.
OUTCOMES - Volitional Control of left leg (tested in supine)

Back 92

Volitional Control of left leg (tested in supine)
Supraspinal control of toe extension and ankle and leg flexion emerged only with epidural stimulation. This occurred after 80 stand training sessions (7 months after implantation; figure 6; webvideos 4 and 5). Voluntary movement was observed in both legs, although the stimulation parameters were different. Technical limitations of the stimulator prevented simultaneous movements of the legs. When the patient was instructed to flex (draw the leg upward), the toe extended, the ankle dorsiflexed and the hip and knee flexed with the appropriate muscle activation. When instructed to dorsiflex the ankle, the foot moved upward with tibialis anterior activation. When instructed to extend the hallux (big toe), the toe moved upward with activation of the extensor hallucis longus. The patient could consciously activate the appropriate muscles for the intended movement, and the timing of activation was closely linked to the verbal commands (figure 6

Front 93

C7-T1 ASIA B paraplegia. No voluntary motor function in the trunk or LE’s. Injured July 2006.
Oct 2007-Nov 2008 participated in 170 locomotor training sessions.
54 hours stand training
108 hours step training
TMS over motor cortex elicits no MEP response in the LE’s
SEP’s recorded in the cortex from LE sensory stim—delayed.
Dec 2009 epidural electrode implantation over spinal cord segment L1-S1 at T11-L1 vertebral levels.
Resumed locomotor training sessions. Epidural stim set for optimum support of standing (sustainable coactivation of bilateral LE muscles) and stepping (rhythmic activity of alternating flexion/extension between right/left leg).
Ave. of 54 minutes of epidural stim per training session. Training session up to 4 hours.

OUTCOMES -Restored bowel/bladder status, sweating and improved sexual function.

Back 93

Restored bowel/bladder status, sweating and improved sexual function.
After training and epidural stimulation, the patient also had functional gains in bladder and sexual function and temperature regulation (webappendix pp 3–4). The patient is now able to voluntarily void with minimum residual volume of urine and has reported improved sexual response and performance. The patient regained diaphoretic capability and the ability to tolerate extremesof temperature.

Front 94

What is the relationship between the neural control of locomotion and other mobility tasks such such as running, sit to stand, supine to sit, standing, sitting?

Networks creating the basic propulsion motions of the body and postures are considered to be located in the spinal cord. Training locomotion and standing improves general mobility status.

Back 94

What is the relationship between the neural control of locomotion and other mobility tasks such such as running, sit to stand, supine to sit, standing, sitting?

Networks creating the basic propulsion motions of the body and postures are considered to be located in the spinal cord. Training locomotion and standing improves general mobility status.

Front 95

Neuromuscular Recovery Scale:
developed by clinicians and researchers between 2000-2008
classification tool
four phases of neuromuscular recovery after SCI based on the individual’s ability to perform task specific movements relative to the pre-injury capability
11 functional tasks related to mobility, standing and walking, which are evaluated in the body-weight support treadmill and over ground environments
7 tasks in overground environment: sit, sit-up, reverse sit up, trunk extension, sit to stand, stand and walk
4 tasks in treadmill environment: stand retraining, stand adaptability, step retraining, and step adaptability


4 phases of functional recovery:

Back 95

4 phases of functional recovery:

Phase 1: primarily wheelchair dependent, unable to stand without assist or compensation, goal is to achieve proper and independent sitting posture, trunk and pelvic control.
Phase 2: Able to stand with/without assist/compensation, beginning to walk with assist or compensation, goal is to achieve proper and independent standing posture
Phase 3: Able to walk with/without assist/compensation, goal is proper and independent walking posture and kinematics
Phase 4: Fully recovered function

Front 96

If the spinal cord can do so much…what are the roles of the rest of the CNS?

What is responsible for choosing gait to meet the goal of the task?

What determines which motor programs should be ready to respond to sensory afference?

What structures set up the activation of the MLR to create the state dependency for locomotion and postural control?

BASAL GANGLIA

Back 96

If the spinal cord can do so much…what are the roles of the rest of the CNS?

What is responsible for choosing gait to meet the goal of the task?

What determines which motor programs should be ready to respond to sensory afference?

What structures set up the activation of the MLR to create the state dependency for locomotion and postural control?

BASAL GANGLIA

Front 97

GENERAL FUNCTION OF THE BASAL GANGLIA: (review from Module 3)

Main functions:

Back 97

Facilitate the automatic execution of selected sequential motor programs while simultaneously suppressing all potentially competing & interfering motor programs.
Regulate initiation & termination of motor sequences, cognitive processes, emotional responses/reactions.
Interrupt behavior to favor/permit a response to a novel/behaviorally significant stimulus.
Scale amplitude/duration/force of postures & movements during the execution of a motor plan.
The basal ganglia function together as a filter—the striatum gathers a variety of info from several different regions in the cortex and detect specific patterns of activity that warrants a response such as movement sequence, attention, emotion, cognitive process. The goal is to permit the right response to occur.

Front 98

Cortical inputs and thalamic inputs and then outputs—gives basal ganglia ability to link automatic movement sequences embedded throughout the nervous system (brainstem, spinal cord) into

Back 98

Cortical inputs and thalamic inputs and then outputs—gives basal ganglia ability to link automatic movement sequences embedded throughout the nervous system (brainstem, spinal cord) into volitional goals/behavioral salience/choice completion. Links the intentional act to with the automatic—selects/tunes the automatic to fulfill volitional intent, so it is appropriate choice, useful to goals wanted by cortex

Front 99

BASAL GANGLIA and Descending pathways: :
A major role of the basal ganglia is to select which motor behaviors should be

Back 99

A major role of the basal ganglia is to select which motor behaviors should be generated in a given instant and when to initiate them and when to terminate them.
The descending reticulospinal pathway is the primary means of conveying locomotor command signals—state dependence—from higher motor centers to spinal interneuronal circuits including the central pattern generators for locomotion.
Raphespinal and Ceuroleospinal systems also modulate the spinal cord systems.

Front 100

There is more to gait than repetitive stepping:
Ongoing Balance/Postural control—postural set, postural responses, visual orientation and head righting reactions.
The ______ system has a key role in the control of body orientation during locomotion

Back 100

Ongoing Balance/Postural control—postural set, postural responses, visual orientation and head righting reactions.
The vestibular system has a key role in the control of body orientation during locomotion. The vestibular sensors sense the orientation of the head and will thereby detect any deviation of the position of the head. Via vestibular interneurons, they activate reticulospinal neurons. The signals for propulsion from the locomotor command regions activate broadly reticulospinal neurons, and the vestibular signals in turn modulate the descending activity in selected groups of reticulospinal neurons. In the diagram, the activity of the reticulospinal populations on the right (RS(R)) and on the left side (RS(L)) are represented .Any deviation to the left or right side will lead to an asymmetric activity of the left and right reticulospinal populations. This asymmetry will lead to a correction of body position

Front 101

There is more to gait than repetitive stepping:
Task and context specific modification—anticipatory, reactive, and adaptability

Back 101

Task and context specific modification—anticipatory, reactive, and adaptability

1. Anticipatory/Feedforward control to meet goal of gait and external constraints/environmental demands.

EXTERNALLY DRIVEN MOTION that depends upon visuomotor transformation: obstacles, turns, targets, routes dotted line in figure

INTERNALLY DRIVEN MOTION using sensorimotor transformation of mechanical events relative to self for postural set, changing gait patterns.
Solid line in figure.

2. Adaptability of gait pattern: Cerebellum
Feedforward adjustments to pattern based
upon error signal

3. Reactive/Feedback error correct: Brainstem
slip, trip/stumble, balance responses

Front 102

1. ADJUSTABILITY OF GAIT—FEEDFORWARD ANTICIPATORY CONTROL
Visuomotor coordination =

Back 102

1. ADJUSTABILITY OF GAIT—FEEDFORWARD ANTICIPATORY CONTROL

Why we can step over obstacles instead of trip over them, why we can change our path to avoid running into another person in the hallway, why we can put our foot on a target, why we can pick a route to follow across the room.
Visuomotor coordination = precision walking occurs through tuning of the locomotor movements mediated at least partially through corticospinal pathways.
PRECISION WALKING

They both contribute to the accurate positioning of the feet required during precision locomotion: however, corticospinal pathways are not significantly involved when walking over a flat surface.

Front 103

Vision is critical for locomotion. Even during locomotion over level terrain, there is a constant need to survey the ground in front of the path of advance for potential obstacles and to scan
the surrounding area for potential threats… Depending on the visual information that is received, the subject will need to make anticipatory modifications of gait. These might include:


From a wide range of experiments, two fundamental ideas have arisen. One is that,

Back 103

altering direction to avoid a threat
making modifications of step length, limb trajectory & foot placement to avoid an obstacle
to place the foot precisely in a secure position if walking over uneven terrain.
One fundamental is that, in most circumstances, intermittent visual information about the environment is sufficient to guide locomotion while the other is that the predicted time to contact (τ) with an object may be used to guide locomotion.

Front 104

Visual sampling was divided between two principal modes.

Back 104

Visual sampling was divided between two principal modes.
1. For periods of time subjects would direct their gaze at the ground a fixed distance in front
of them so that the visual field moved along with the subject. They referred to this as travelling fixation and the visual information obtained during this time presumably optic regions information about heading and velocity.

2. Interspersed with these periods of travelling fixation, the subjects saccade to the obstacle placed in their path; this information is presumably used to integrate the location of the object with the proprioceptive and visual information concerning the subject's locomotion. In extremely
difficult situations, such as stepping from one stone to another, subjects may fixate the location of their next footfall in every step.

Front 105

Visual fixation vs. peripheral visual field.

Back 105

gaze fixation is typically about 2 steps ahead

peripheral visual field must be used to avoid collisions with people in a crowded mall. It is also important for monitoring changes in ground terrain and for adjusting foot placement and lower limb trajectory for stepping over obstacles

Front 106

2. ADAPTABILITY OF GAIT:
what structures are involved?

Back 106

2. ADAPTABILITY OF GAIT: Why we can adjust to a moving walkway (or to a split belt treadmill) while we are still walking.
Medial cerebellar regions play a primary role in regulating extensor tone, sustaining upright stance and dynamic balance control, and modulating the rhythmc flexor and extensor activity that makes up the locomotor pattern.
The intermediate regions have a minimal role in stance and posture but are important for directing limb placement and controlling muscle activity for timing, amplitude and trajectory of limb movements
Lateral cerebellum is less important for the control of balance and uninterrupted level walking, but does play a role in adjusting the locomotor pattern in novel contexts or when strong visual guidance is required.

Front 107

3. ONGOING EQUILIBRIUM DURING GAIT—POSTURAL SET AND POSTURAL RESPONSES AND CORRECTIVE REACTIONS
Feedback loops

Back 107

3. ONGOING EQUILIBRIUM DURING GAIT—POSTURAL SET AND POSTURAL RESPONSES AND CORRECTIVE REACTIONS

A. Somatosensory feedback loops: Why we trip/stumble, pull a foot off a tack, and slip forward

And why we keep going—load signal of the stance limb and extension signal of the stance limb


B. Vestibular feedback loops stabilize the motions of the head/neck and eyes while the body moves underneath: Why we don’t feel motion sick when we walk? How we distinguish between sensory afference from our movements and from something external to us.

Front 108

How does a stumble differ in early vs. late swing phase
Specificity of the stumble depends upon the phase of gait and the position of the limb

Back 108

The most common movement outcome was an elevating strategy of the swing limb in response to the early swing perturbation & a lowering strategy in late swing perturbation.
Elevating strategy comprised a flexor component of swing limb & extensor component of stance limb. Was temporal sequencing of the swing limb biceps femoris prior to swing limb rectus femoris response to remove the limb from the obstacle prior to accelerating the limb over the obstacle. The extensor response of the stance limb generated early heel-off to increase height of the body.
lower limb joints collaborated to increase height of the centre of mass & provide extra time to
extend the swing limb in preparation for landing.
Flexion of the swing limb would be dangerous in late swing perturbation as the swing limb is approaching the ground & body mass is forward of stance foot. Instead, lowering strategy was accomplished by inhibitory responses of swing limb vastus lateralis &/or excitatory swing limb BF

Front 109

Flexion of the swing limb would be dangerous in response to the late swing perturbation as the swing limb is approaching the ground and the body mass has passed forward of the stance foot. Instead, a

Back 109

Flexion of the swing limb would be dangerous in response to the late swing perturbation as the swing limb is approaching the ground and the body mass has passed forward of the stance foot. Instead, a lowering strategy was accomplished by inhibitory responses of the swing limb vastus lateralis and/or excitatory responses of the swing limb biceps femoris. Both of these responses resulting in a rapid lowering of the limb to the ground with a flat foot or forefoot landing and a shortening of the step length.

Front 110

Subjects who normally walk with _____ were predisposed to experience less severe slips when encountering an unexpected slippery floor. Finally, anticipation of a slippery surface resulted in

Back 110

Subjects who normally walk with greater ankle muscle co-contraction were predisposed to experience less severe slips when encountering an unexpected slippery floor. Finally, anticipation of a slippery surface resulted in more
powerful muscular activity and muscle co-contraction at the ankle and knee compared to baseline gait, as well as earlier onsets and longer durations in the posterior muscles’ activation.

Front 111

The ability to navigate and orient through the environment requires knowledge not only of inertial motion, but also of which components of vestibular activation result from active (i.e., self-generated) and passive (i.e., externally applied) movements. How does the brain differentiate between sensory inputs that arise from changes in the world and those that result from our own voluntary actions?

Back 111

Von Holst & Mittelstaedt (1950) proposed the principle of reafference, in which a copy of the expected sensory results of a motor command (termed reafference) is subtracted from the actual sensory signal to create a perception of the outside world (termed exafference). Thus, the nervous system can distinguish sensory inputs that arise from external sources from those that result from self-generated movements. More recent behavioral investigations have generalized this original proposal by suggesting that an internal prediction of the sensory consequence of our actions, derived from motor efference copy, is compared with actual sensory input…. sensory information arising from self-generated behaviors can be selectively suppressed at the level of afferent fibers or the central neurons to which they project.
Consistent with this idea, fMRI studies suggest that the cerebellum plays a similar role in the suppression of tactile stimulation during self-produced tickle.

Front 112

How do we not respond to the head movements we make? Anticipatory control and the role of efference copies:

Back 112

How do we not respond to the head movements we make? Anticipatory control and the role of efference copies:
“Vestibular signals that arise from self-generated head movements are inhibited by a mechanism that compares the brain’s internal prediction of the sensory consequences to the actual resultant sensory feedback. Accordingly, during active movements of the head on body, a cancellation signal is gated into the vestibular nuclei only in conditions where the activation of neck proprioceptors matches that expected on the basis of the neck motor command.” This interaction among vestibular, proprioceptive, and motor efference copy signals occurs as early as the first-order vestibular neurons.

Front 113

1. What are the different types of memory? Where are memories stored?
Memory System: Episodic memory
Major Anatomical Structures Involved:
Length of Storage of Memory:
Type of Awareness:
Examples:

Back 113

“A memory system is a way for the brain to process information that will be available for use at a later time.”

Memory System: Episodic (your life)
Major Anatomical Structures Involved: Medial temporal lobes, anterior thalamic nucleus, mamilary body, fornix, prefrontal cortex
Length of Storage of Memory: minutes to years
Type of Awareness: explicit, declarative
Examples: remembering a short story, what you had for dinner, and what you did on your last birthday

Front 114

1. What are the different types of memory? Where are memories stored?
Memory System: semantic memory
Major Anatomical Structures Involved:
Length of Storage of Memory:
Type of Awareness:
Examples:

Back 114

“A memory system is a way for the brain to process information that will be available for use at a later time.”

Memory System: semantic
Major Anatomical Structures Involved: inferolateral temporal lobes
Length of Storage of Memory: minutes to years
Type of Awareness: explicit, declarative
Examples: knowing who was the first president of the US, the color of a lion, and the difference between a fork and a comb

Front 115

1. What are the different types of memory? Where are memories stored?
Memory System: procedural memory
Major Anatomical Structures Involved:
Length of Storage of Memory:
Type of Awareness:
Examples:

Back 115

“A memory system is a way for the brain to process information that will be available for use at a later time.”

Memory System: procedural memory
Major Anatomical Structures Involved: basal ganglia, cerebellum, supplementary motor area
Length of Storage of Memory: minutes to years
Type of Awareness: explicit or implicit, nondeclaritive
Examples: driving with a standard transmission (explicit) and learning the sequence of numbers on a touch tone phone without trying (implicit)
without trying = without conscious recall of the numbers

Front 116

1. What are the different types of memory? Where are memories stored?

Memory System: working memory
Major Anatomical Structures Involved:
Length of Storage of Memory:
Type of Awareness:
Examples:

Back 116

“A memory system is a way for the brain to process information that will be available for use at a later time.”

Memory System: Working memory
Major Anatomical Structures Involved: Phonologic: prefrontal cortex, Brocca's, Wernicke's. Spatial: prefrontal cortex, visual-association areas.
Length of Storage of Memory: seconds to minutes; information actively rehearsed or manipulated
Type of Awareness: explicit, declarative
Examples: Phonologic: keeping a phone number 'in your head' before dialing. Spatial: mentally following a route or rotating an object in your mind

Front 117

Two broad classes of long-term memory:

What subclasses do they have?

Back 117

Declarative and non-declarative
Declarative - characterized by the capacity for conscious recollection
2 Subclasses:
Episodic - autobiographical events
Semantic - facts and general knowledge

Non-Declarative - encompasses diverse unconscious learning and memory abilities
4 subclasses:
Procedural memory: sensorimotor and cognitive skills and habits. Uses basal ganglia, cerebellum, cortex
Priming: uses neocortex
Simple classical conditioning: uses amygdala, cerebellum
Habituation sensitization: reflex pathways

Front 118

The hippocampus and it’s pathway can be viewed like the Basal Ganglia and Cerebellum pathways roles in motor control/motor learning—

Back 118

The hippocampus and it’s pathway can be viewed like the Basal Ganglia and Cerebellum pathways roles in motor control/motor learning—through the “loops” of inputs/outputs with the cortex, they provide a specific function that transforms cortical inputs into memories or for action/retrieval.

Front 119

“Although we do not completely understand how the medial temporal lobes store and retrieve memories, our current understanding from cognitive neuroscience is as follows.

An individual experiences an episode of their life, such as having breakfast in the morning. The cortically distributed patterns of actual activity representing the sights, sounds, smells, tastes, emotions, and thoughts during that episode are transferred first to the _________ _____ and then to the _____ _____. After being transferred to the

Back 119

“Although we do not completely understand how the medial temporal lobes store and retrieve memories, our current understanding from cognitive neuroscience is as follows.

An individual experiences an episode of their life, such as having breakfast in the morning. The cortically distributed patterns of actual activity representing the sights, sounds, smells, tastes, emotions, and thoughts during that episode are transferred first to the parahippocampal gyrus (PhC above) and then to the hippocampus proper. After being transferred to the entorhinal cortex (ErC above), the information is processed in the dentate gyrus (DG), and then transferred to the CA3 region where it is further processed. It is in this CA3 region where the critically important “hippocampal index” is assigned, allowing the memory to be stored in a unique way so it can be later recalled.

Front 120

Typically memories are retrieved when a cue from the environment matches a part of the stored memory. Continuing our breakfast example, years later the individual might now bite into a little cake that tastes remarkably like the one that he had previously at breakfast. This sensory cue is transferred from the cortex to the

Back 120

Typically memories are retrieved when a cue from the environment matches a part of the stored memory. Continuing our breakfast example, years later the individual might now bite into a little cake that tastes remarkably like the one that he had previously at breakfast. This sensory cue is transferred from the cortex to the parahippocampal region and to the hippocampus. After the cue is transferred from the entorhinal cortex it now goes directly to the CA3 region where the orginial hippocampul index is retrieved. When found the hippocampal index may be used to retrieve much of the original pattern of the neural activity representing the original episode stored in memory. This retrieval pattern of activity may then be transferred to the CA1 region, the subiculum, the entrorhinal cortex, and then back to the cortex—recreating the sights, sounds, smells, tastes, emotions and thoughts of the original memory episode

Front 121

The hippocampus remains critical for memory retrieval until

Back 121

The hippocampus remains critical for memory retrieval until a process known as consolidation occurs. Much research still needs to be done to better understand consolidation, but one thought is that once a memory is consolidated the distributed pattern of cortical neural activity is directly linked together, such that when a cue is encountered, the memory may be retrieved directly from cortical-cortical connections, without the need for the hippocampus. And, although there are many details that need to be learned, there is much data suggesting that sleep is critical for consolidation to occur. “ from Budson AE Understanding Memory Dysfunction The Neurologist 2009;15(2):71-79.

Front 122

HIPPOCAMPUS and DECLARATIVE/EXPLICIT MEMORY:

INPUTS—

PATHWAYS TO LONG TERM STORAGE:

Back 122

HIPPOCAMPUS and DECLARATIVE/EXPLICIT MEMORY:

INPUTS—integrates/relates multiple inputs about the same object—3 blind monks palpating an elephant analogy (see next slide).

PATHWAYS TO LONG TERM STORAGE:
All unimodal sensory regions and multimodal Association Cortices parahippocampal and rhinal cortices hippocampus  parahippocampal and rhinal cortices  All unimodal sensory regions and multimodal Association Cortices

Hippocampus is active during encoding of memory and during the retrieval early in the memory process.

Front 123

The prefrontal and parietaloccipital association cortices are thought to have a central role in

Back 123

The prefrontal and parietaloccipital association cortices are thought to have a central role in cognition, for example in the control of attention for working memory—spatial tablet. The PreFrontalCortex, especially its lateral aspect, is critical for the maintenance and manipulation of information—working memory.

Front 124

Relationship between working memory (frontal lobes), recent (medial temporal), and long term memory (other cortical regions/inferior lateral temporal lobe).

Back 124

“Over the past 10 years it has become increasingly clear that in addition to the medial temporal lobes and Papez’s circuit, the frontal lobes are also important for episodic [and semantic] memory. Whereas the temporal lobes are critical for retention of information, the frontal lobes are important for the:

Acquisition/registration/encoding of information
Retrieval of information without contextual and sensory cues
Recollection of the source of information
Assessment of the temporal sequence and recency of events.

Also notable is the left temporal and frontal lobes are most active when a person is learning words, and that the right medial temporal and right frontal lobes are most active when learning visual cues.” from Budson AE Understanding Memory Dysfunction The Neurologist 2009;15(2):71-79.

Front 125

4 key aspects about memory learned from working with HM:

Back 125

4 key aspects about memory learned from working with HM:
Hippocampus and the medial temporal lobes are necessary for formation of new declarative memories.
Motor learning/procedural memory can occur independently from declarative learning.
Working memory/short term memory (frontal lobes) vs. long term memory (medial temporal lobes) use different structures
Episodic memory uses the hippocampus more than semantic memory for retrieval which is found in the cortex. Consolidation overtime—how far back retrograde amnesia can go.

Front 126

What is the difference between Motor Skill Learning vs. Motor Adaptation? Which regions of the nervous system are involved in these processes—and how does this change with practice?

MOTOR ADAPTATION

Back 126

MOTOR ADAPTATION and the return to baseline levels of performance in response to external perturbations. An example of adaptation to an external perturbation is the response to directional errors in visually guided reaching movement caused by prism glasses: with practice, performance returns to the ‘‘baseline’’ level. Importantly, adaptation may not require the acquisition of new motor synergies or movement patterns, as it engages movements that were achieved throughout life. Trial and Error Learning

Adaptation is an error-driven process that adjusts sensorimotor mappings of well learned movements to account for new, predictable demands. This new mapping is stored and must be unlearned when normal conditions are restored. Although an adapted pattern can be unlearned, it may not be forgotten. Rather, subjects who have previously adapted show
some memory of the adapted state when reexposed to the same perturbation. Thus, adaptation training can lead to storage of the original and th

Front 127

What is the difference between Motor Skill Learning vs. Motor Adaptation? Which regions of the nervous system are involved in these processes—and how does this change with practice?
“MOTOR SKILL LEARNING”—involves

Back 127

“MOTOR SKILL LEARNING”—involves the acquisition of a new pattern of muscle activations, like a sequence of finger or arm movements.

Acquisition, consolidation, and retention of a new motor skill involves the acquisition of new movement qualities and/or muscle synergies that enhance performance beyond preexisting levels. Skills seem to take longer to acquire than adaptation and sometimes do not reach plateau levels after years (ie, learning to play piano or basketball). Reinforcement reward-based learning.

Such studies have shown that training with random practice, where a series of skills are learned and practiced in short, randomly distributed blocks, leads to better retention days later than what results from blocked practice, where a skill is practiced exhaustively before switching.

Front 128

Which regions of the nervous system are involved in these motor learning processes—and how does this change with practice?

Back 128

Which regions of the nervous system are involved in these motor learning processes—and how does this change with practice?

Cortico-basalganglia
Cortico-cerebellar

…the cortico-basal ganglia circuits do not constitute the only anatomical system implicated in the acquisition and planning of skilled actions. The cerebellum and its motor-associated structures, like the somatosensory motor cortex and ventral PMC forming the cortico-cerebellar loop through the dentate nucleus and ventralposterior lateral nucleus of the thalamus [59], have also been shown to contribute to motor learning. Dynamic brain plasticity within the striatum and cerebellum, as well as functional interactions between these two cortico-subcortical systems has been reported depending on the stage of the learning process, nature (i.e., new versus learned motor behavior) of the action being planned and the type of skill being acquired (Motor Sequence Learning, Motor Adaptation)

Look at chart on slide 22!

Front 129

ACQUISITION refers to

Back 129

ACQUISITION refers to the uptake of (new) information during learning/during practice and its encoding into a vulnerable memory trace.

Memory trace is Vulnerable to:
Interference
Decay/Forgetting

Front 130

CONSOLIDATION refers to

Back 130

CONSOLIDATION refers to the period of time after practice—where no practice is occurring—and includes memory
stabilization of the newly encoded memory, and/or
memory enhancement or offline improvement of skill as well as integration with pre-existing long-term declarative memories

Front 131

RETRIEVAL or RETENTION refers to

Back 131

RETRIEVAL or RETENTION refers to the recall of stored memories after a delay or a period of time post practice.

Front 132

In recent years strong evidence has accumulated that sleep supports consolidation of both _____
The consolidating effect of sleep was demonstrated principally in two ways.
Stabilization: Compared with wakefulness, sleep after learning stabilizes newly encoded representations by increasing their resistance to interfering inputs. In declarative memories ,the effect of post-learning sleep is seen as diminished forgetting of the information learned before a sleep perior.

Improvement: Delayed retrieval/recall is improved relative to that of post-learning wakefulness if acquisition is followed by a period of sleep. Sleep induces an actual gain in skill as well as long-term persistence of declarative memories.

A leading concept assumes that consolidation during sleep evolves from repeated reactivation of the neuronal networks that were previously used to encode the information. Reactivation is supposed to support both synaptic consolidation and systems c

Back 132

both procedural & declarative mem
Stabilization: Compared w/ wakefulness, sleep after learning stabilizes newly encoded representations by increasing their resistance to interfering inputs. In declarative,the effect of post-learning sleep is seen as diminished forgetting of info
Improvement: Delayed retrieval/recall is improved relative to post-learning wakefulness if acquisition is followed by sleep. Sleep induces a gain in skill as well as long-t persistence of declarative memories
A leading concept assumes that consolidation during sleep evolves from repeated reactivation of neuronal networks that were used to encode the information. Reactivation may support both synaptic consolidation & systems consolidation, which involves transfer of memory representations to other neuronal networks for long-t storage. The brain uses the same limited neuronal network capacities for the immediate processing and long-t storage of huge info– mutually exclusive functions that t take place simultan

Front 133

What is the difference in sleep-related consolidation between Explicit/Declarative learning and Implicit motor learning?

Back 133

What is the difference in sleep-related consolidation between Explicit/Declarative learning and Implicit motor learning? Implicit learning does not require sleep to consolidate.

Front 134

Preferential consolidation of explicit aspects of memory
Whether a memory benefits from sleep depends on several factors, including

Back 134

Preferential consolidation of explicit aspects of memory
Whether a memory benefits from sleep depends on several factors, including the ‘explicitness’ of memory (See Box on the left). Robertson et al. 2004 trained subjects on a procedural serial reaction time task (SRTT—finger sequence test) either under explicit or implicit conditions – during training subjects were either aware or remained unaware of the underlying sequence of cue positions throughout training. Skill acquisition was measured by the difference in reaction times to the trained sequence vs. a random sequence. Interestingly, a gain in skill associated with post-training sleep was found only when subjects were aware of the sequence. In the implicit task, delayed performance gains were observed in both the sleep and wake conditions consistent with the effect of time.

Front 135

To summarize, sleep supports the consolidation of both

Back 135

To summarize, sleep supports the consolidation of both declarative and procedural memories. In conditions of competition between explicit and implicit moments, explicit aspects of memory representations seem to be preferentially strengthened by sleep.

Explicitness at encoding predisposes a memory for sleep-dependent consolidation and probably also directs how implicit aspects of a memory representation are bound into the sleep-dependent consolidation process. Explicit encoding involves a network of brain structures fundamentally relying on coordinated activation of prefrontal cortical and hippocampal circuitry.

Front 136

What is the difference between stabilization and offline improvement?

Back 136

In offline learning, performance of a skill improves between periods of practice. From consolidation, often depends on sleep

With stabilization, skill performance is the same as at the end of the last practice