Chapter 8 -Control Of Movement

Front 1

Brief Stimulus Vs Complex stimulus of Motor Cortex

Back 1

Brief movements of a particular part of body vs complex movements (ex. leaping, reaching to grasp etc.)

Front 2

Major inputs and outputs of M1

Back 2

Input: Cortical sensorimotor signals, SMA and PMC

Output: descending motor pathways

Front 3

Where do PMC and SMA receive sensory info?

Back 3

Parietal and temporal lobes

Front 4

SMA

Back 4

Medial

Learning and performing sequences of movements i.e planning what is to come

Neurons in SMA encode certain elements of sequence

Front 5

Pre-SMA

Back 5

Anterior to SMA

Involved in control of spontaneous (involuntary behavior) movement or perception of control (activated prior to spontaneous movement)

Stimulation: urge and anticipation of movement (vs execution)

Front 6

Lateral Group of descending tracts

Back 6

Controls independant limb movements (esp. hands & fingers)

1. Corticobulbar tract

2. Corticospinal tract

3. Rubrospinal tract

Front 7

Ventromedial Group of Descending tracts

Back 7

Controls automatic movements - gross movements of trunk & coordinated movements of trunk & limbs in posture & locomotion

Terminate on ventromedial SC motor neurons

1. Vestibulospinal tract

2. Reticulospinal tract

3. Tectospinal tract

4. Ventral corticospinal tract

Front 8

Lateral Corticospinal tract

Back 8

M1 + SMA -> ventral midbrain (cerebral peduncles) -> medullary pyramids -> cross over in caudal medulla & forms pyramidal tract

Controls movement of distal part of limbs ex. hands, fingers, arm

Synaspse with motor neurons in SC GM

Front 9

Ventral Corticospinal tract

Back 9

No cross over - descend in ipsilateral SC

-> upper leg & trunk movements

Front 10

Corticobulbar tract

Back 10

Terminates in medulla - motor nuclei of face/tongue/neck/extrocular eye muscles

Front 11

Rubrospinal tract

Back 11

Originates in midbrain red nucleus

Receives input from Corticorubral tract & Cerebellum

Terminates on motor nuclei of SC conrolling independent movement of forearm and hands

Front 12

Vestibulospinal Tract

Back 12

Cell bodies in vestibular nuclei

Control of posture in response to info from vestibular system

Front 13

Tectospinal tract

Back 13

Cell bodies in Superior colliculus (tectum)

Project to SC

Coordinate head and trunk movements with eye movements

Front 14

Reticulospinal tract

Back 14

Cell bodies in various nuclei of Reticular formation (throughout BS)

Control automatic functions ex. locomotion, respiration, coughing etc.

Front 15

PMC

Back 15

Learning and executing responses that are signaled by arbitrary stimuli (ex. auditory, visual, tactile) - must be learned

Non arbitrary ex. spatial cue for reaching

Component of mirror neuron system (i.e imitating & understanding/predicting other's actions)

Front 16

Muscimol

Back 16

GABA agonist - inhibits neural activity

Front 17

TMS

Back 17

Temporarily inactivates brain regions

Front 18

Posterior parietal cortex involvement with intention to move

Back 18

Associated of awareness of an intention to move prior to the movement

Monitoring own plans and intentions

Stores info about decision + transmits to SMA

Front 19

Prefontal Cortex

Back 19

Involved in decision to move

Transmits to PostPcortex --> SMA

Front 20

Mirror neurons

Back 20

Located in:

Area F5 of monkeys (ventral PMC)

Inferior parietal lobule

Fire when monkeys perform an action or when monkey observe same action performed by others (role in ability to imitate movements)

-> also activated by sounds indicating occurence of familiar action

Front 21

Role of mirror neuron circuit

Back 21

Help us understand actions and intentions of others (more activation with context)

More with expert situations

Speculation: involved in the feedback ex smile, funny joke etc

Front 22

Parietal Reach Region

Back 22

In Medial Posterior Parietal Cortex

Control of pointing or reaching with hands

Front 23

aIPS

Back 23

Anterior part of Intraparietal sulcus

Recognition of grasping movements & their execution

Visual input from dorsal visual stream

When watching vid of hand grasping an object - info about shape of hand activated aIPS and info about nature of object activated ventral stream

Front 24

Apraxias

Back 24

Deficit in skilled movement caused by damage to left frontal or parietal lobe

Front 25

Limb apraxia

Back 25

Lesions:

1. Anterior Corpus Callosum

2. Left frontal lobe motor cortex

3. Left intraparietal sulcus

Problems with mvmt of arms/hands/fingers: movement of wrong limb, incorrect movement of correct part of limb, correct movement in incorrect sequence

Assessed by imitation of hand gestures

Damage to leftP lobe (involved with own body) -> both hands apraxia bt not RightPlobe (involved with extrapersonal space)

Find difficult movements without object pantomiming

Front 26

Oral apraxia

Back 26

Problems with muscles used in speech

Front 27

Apraxic Agraphia

Back 27

Problems with writing

Front 28

Constructional Apraxia

Back 28

Caused by lesions to right Plobe

-> unable to draw or assemble objects from elements

-> inability to perceive/imagine geometric relationships (spatial aspect): difficulty with tasks involving spatial perception/navigation (remember dorsal RPlobe - ''where'' visual stream)

Front 29

Putamen & Caudate

Back 29

Telencephalic nuclei of BG

Input nuclei involved in control of voluntary movement

Front 30

Ventral Anterior & Ventral lateral Th.nuc

Back 30

Receive projections of BG GP & project to cortex

Front 31

Globus Pallidus

Back 31

Telencephalic nuclei - major output of BG

Internal & external segments

Front 32

STN

Back 32

Ventral to BG

Major subcortical motor system structure

Front 33

Direct Pathway

Back 33

Cortex -> C/P -- Gpi --Thalamus --> Cortex

Inh on Gpi - excitatory on movement

D1 exc dopamine receptors

Front 34

Indirect Pathway

Back 34

Cortex --> C/P -- Gpe --STN -->GPi -- Thal -> Cortex

Exc on GPi - inh on movement

D2 inh dopamine receptors

Front 35

Hyperdirect pathway

Back 35

Pre-SMA -> STN -> GPi -> Thal -> Cortex

Exc on Gpi - inh on movement

Short delay: quickly prevents/stops movements initiated by direct pathway

Front 36

Basal Ganglia Inputs and Outputs

Back 36

Inputs: Cortex and SN

Outputs: M1, SMA, PMC (via thalamus) and Motor nuclei of BS that control ventromedial pathways

Front 37

Basal Ganglia - Hyperkinetic disorders

Back 37

Involuntary movements & Choreiform (writhing/twitching) ex. Huntingtons/Tourettes

Front 38

Parkinson's Disease

Back 38

Hypokinetic disease of BG (prob with vol. mvmt)

Neurodegenerative - dopamine neurons in SN - causes imbalance between direct & indirect pathway

Symptoms: resting tremor, muscular rigidity, postural instablity & slowness of movement)

Front 39

L-Dopa

Back 39

Treatment for Parkinson's - increases amount of dopamine

If too much: dyskinesia & dystonia (involuntary movements and postures)

Does not work indefinitely since number of dopamine neurons decline & symptoms worsen

Front 40

Huntington's chorea

Back 40

Genetic - no treatment

Uncontrollable movements (Huntington's dance)

Caused by degeneration of C/P creating an imbalance in pathways: reduction in inhibition provided by GABA neurons of C/P affecting indirect pathway (Gpe more active)

Caused by dom gene on chr 4

then other gaba neurons degenerate and patient dies from immobilty

Front 41

Cerebellum

Back 41

2 hemispheres & flocculus (small lobe projecting from ventral surface)

More sulci/gyri than neocortex

Timing/accuracy of movements

Front 42

Lateral Hemispheres

Back 42

Control of independent limb movements (Ballistic movements: rapid/skilled - need to rely on timing vs feedback)

Input: Motor cortex (info on start of mvmt) via pontine nuc

Projects to dendate nuclei (deep cerebellar nuclei - controls corticospinal and rubrospinal systems) --> ventrolateral thalamus -> M1

Front 43

Damage to lateral zone

Back 43

Decomposition of movement & weakness (disjointed/separate movements)

Front 44

Floculonodular lobe

Back 44

Control of postural Reflexes

Input: vestibular system

Projects to Vestibular nuclei

Front 45

Intermediate Zone of Cerebellum

Back 45

Projects to Interposed nuclei -> Rubrospinal tract

And sends projections to VLThal.n -> Motor cortex

Front 46

Damage to intermediate zone

Back 46

Limb rigidity

Front 47

Vermis

Back 47

Midline of cerbellum

Input: Somatosensory info

Output: Fastigial Nucleus -> vestibulospinal and reticulospinal tract

Front 48

Pontine nucleus

Back 48

Input to cerebellum (has info from frontal association cortex and M1 about intended mvmt)

Projects to lateral zones

Front 49

Reticular formation

Back 49

Large # of nuclei in core of Medulla/Pons/Midbrain

Controls gamma motor system - regulates tonus for posture and locomotion

Controls very specific behaviors as well like moving tongue from left to right

Front 50

Mesencephalic Locomotor Region

Back 50

Midbrain - part of reticular formation

Ventral to IC

Stimulation causes alternating movement of limbs seen in locomotion

Controls via reticulospinal tract neurons so does not send fibers directly to SC

Front 51

Frontopolar cortex

Back 51

Rostral tip of cerebral hemispheres in PFC

Critical in role in deciding to make a motor response

Front 52

Audiovisual neuronss

Back 52

Mirror neurons: respond to sound of particular actions and to the sight of them being performed

- sound of an action will remind you of the action

- sight of action will activate auditory cortex (reminds you of how it sonds), mirror neuron circuit and visual cortex

Front 53

Damage to inferior frontal gyrus

Back 53

- apraxic patient (limb)

- no damage to paretial

-causes deficits in comprehension of gestures

while F and P lobes are both involved in imitating hand gestures, Frontal cortex plays more imp role in recognizing the meaning of these gestures