Physiology Neuro

Front 1

What is adequate stimulus

Back 1

adequate stimulus is the "best" stimulus for a given receptor

Front 2

What is receptive field?

Back 2

Presentation to the receptor's receptive field (the region of the receptor sheet that causes a change in the response of a receptor or neuron when stimulated) causes ion conductance changes that produces a generator potential

Front 3

What is generator potential

Back 3

generator potential is graded, local, and if sufficient to depolarize the neuron beyond threshold, causes action potentials to be generated.

Front 4

Name the Coding mechanisms available for representing a stimulus in the nervous system

Back 4

Modality (submodality; quality), Intensity, Location, and Timing (onset and offset).

Front 5

All stimuli are "multi-dimensional" and have at least_____dimensions that the nervous system has to code in the action potentials of sensory neurons

Back 5

4

Front 6

____ of a stimulus: "What" the sensation is

Back 6

modality

Front 7

Most often this information is carried in the nervous system by a code known as _____.

Back 7

"labeled-lines".

Front 8

______ of a stimulus: "How much" sensation is present.

Back 8

intensity

Front 9

The code for stimulus intensity is known as the

Back 9

"frequency code

Front 10

This code includes the total number of_____ generated per unit time in affected sensory neurons as well as the total number of neurons activated.

Back 10

action potentials

Front 11

______ of a stimulus: "Where" the sensation originates.

Back 11

location

Front 12

concept of receptive field pertains to what coding mechanism

Back 12

location

Front 13

Precise location information is usually coded by the ___.

Back 13

"population code".

Front 14

____of a stimulus: "When" the stimulus starts and stops.

Back 14

timing

Front 15

concept of adaptation pertains to what coding mechanism

Back 15

timing

Front 16

Sensory receptors are classified as rapidly adapting or slowly adapting based upon their response to a _____.

Back 16

sustained stimulus

Front 17

"" coding accomplishes coding of stimulus onset, duration, and offset

Back 17

Temporal pattern

Front 18

Classification (traditional) by where they are:

Back 18

Exteroceptive, proprioceptive, interoceptive

Front 19

Classification by type of energy transduced

Back 19

mechanoreceptors thermoreceptors
nociceptors

Front 20

Submodality Subserved: Touch
Specialized Receptor :
Adequate Stimulus :

Back 20

Specialized Receptor: Meissner?s Corpuscle (RA) Adequate Stimulus : Active skin displacement

Front 21

Submodality Subserved:Pressure
Specialized Receptor :
Adequate Stimulus :

Back 21

Specialized Receptor:Merkel Cells(SA)Ruffini Endings (SA)

Adequate Stimulus :Static skin displacement

Front 22

Submodality Subserved:Vibration
Specialized Receptor :
Adequate Stimulus :

Back 22

Specialized Receptor:Pacinian Corpuscles (RA)
Adequate Stimulus:Vibration (60-500 Hz)

Front 23

Submodality Subserved:Flutter
Specialized Receptor :
Adequate Stimulus :

Back 23

Specialized Receptor:Meissner?s Corpuscles (RA) Adequate Stimulus :Slow Vibration (5-40 Hz)

Front 24

Submodality Subserved: Hair Movement
Specialized Receptor :
Adequate Stimulus :

Back 24

Specialized Receptor:Hair Follicle Endings (RA) Adequate Stimulus :Hair deflection

Front 25

Submodality Subserved: Position sense and kinesthesia
Specialized Receptor :
Adequate Stimulus :

Back 25

Specialized Receptor:Joint, muscle, and skin receptors (RA and SA) Adequate Stimulus :Joint position and movement

Front 26

Transducer mechanisms

Back 26

Merkel cell

Front 27

: stretch sensitive channels in the membrane of this specialized cell causes the release of a transmitter. This transmitter causes action potential generation in the first order sensory neuron.

Back 27

Merkel cell

Front 28

receptors (RA) signal dynamic (active or changing) stimulus properties; e.g. movement of the skin, velocity, acceleration.

Back 28

Rapidly adapting

Front 29

receptors (SA) signal static (steady state) properties; e.g. stimulus duration, intensity

Back 29

Slowly adapting

Front 30

: a recording from many neurons simultaneously. Differs from action potential in a single neuron. Instead of being all-or-none

Back 30

Compound action potential

Front 31

varies in amplitude and overall size depending upon the stimulus intensity.

Back 31

compound action potential

Front 32

Significance of multiple peaks in the waveform of a compound action potential - different peaks reflect of____ axons (conduction velocity);

Back 32

size

Front 33

peaks also have relationship to _______.

Back 33

sensation

Front 34

#Ia, Ib
Origin: Muscle spindle primary ending
Golgi tendon organ

Back 34

Fiber Type:
Aa
Aa

Front 35

# II
Origin:
Touch, pressure, vibration, flutter, hair, proprioception
Muscle spindle secondary ending

Back 35

Fiber Type: Ab

Front 36

# III
Origin:Fast pain, cold, some touch (non-discriminative)

Back 36

Fiber Type: Ad

Front 37

#IV
Origin: Slow pain, temperature, other receptors

Back 37

Fiber Type:C

Front 38

Two major systems are involved in detecting and processing somatosensory events

Back 38

dorsal column system
anterolateral system

Front 39

dorsal column system -- predominately concerned with discriminative aspects of ____ .

Back 39

somesthesia

Front 40

the ability to accurately detect the quality, intensity, location, and timing of somatic stimuli

Back 40

somesthesia

Front 41

anterolateral system

Back 41

-- subserves pain and temperature and is believed to contribute less precise information about touch and pressure than the dorsal column system.

Front 42

Segmental anatomy

Back 42

: cross-sectional anatomy of the spinal cord

Front 43

Longitudinal anatomy:

Back 43

dermatomes and myotomes

Front 44

dermatomes and myotomes

Back 44

considered as spinal cord segments; each with input and output

Front 45

ipsilateral projection via dorsal root to dorsal white matter without a synapse

Back 45

Primary afferents (1st order neuron):

Front 46

First synapse in dorsal column nuclei include.

Back 46

(Nucleus Gracilis and n. Cuneatus)

Front 47

First synapse in dorsal column nuclei what does it cause?

Back 47

lateral inhibition and descending control of ascending information

Front 48

Receptive field changes for 2nd order neurons

Back 48

Lateral inhibition

Front 49

Lateral inhibition is a mechanism that enhances contrast in the nervous system--helps distinguish ____stimuli, etc.

Back 49

2 closely spaced

Front 50

Efferent (descending) control of ______ information

Back 50

sensory

Front 51

Axons of 2nd order neurons form the ______.

Back 51

medial lemniscus

Front 52

2nd order neurons axons cross the midline of the nervous system as they project to the_____.

Back 52

thalamus

Front 53

VPL nucleus of the thalamus contains the cell bodies of ____ neurons in this pathway

Back 53

3rd order

Front 54

The ______ is a major nucleus that processes virtually all ascending (sensory) information.

Back 54

thalamus

Front 55

Axons of these neurons project to the somatosensory cortex

Back 55

3rd order

Front 56

SI =

Back 56

(primary somatosensory cortex).

Front 57

SII =

Back 57

(secondary somatosensory cortex)

Front 58

area coinsides with the postcentral gyrus (also known as Brodmann's areas 3a, 3b, 1 and 2.

Back 58

SI

Front 59

information from the face and head is carried by a ___(the Trigeminal nerve) and projects to the thalamus (VPM) and cortex (SI and SII).

Back 59

cranial nerve

Front 60

Dorsal Column System Input via ________ nerve fibers

Back 60

large myelinated

Front 61

Representation of the body:
Spinal cord:

Back 61

hand lateral, foot medial

Front 62

Representation of the body: Dorsal column nuclei:

Back 62

hand lateral, foot medial

Front 63

Representation of the body: VPL of thalamus:

Back 63

foot lateral, hand medial (face in VPM, medial to body representation)

Front 64

Representation of the body:
Somatosensory cortex:

Back 64

face lateral, foot medial

Front 65

Most neurons have _________relatively contralateral receptive fields

Back 65

small, localized,

Front 66

Receptive fields on the distal portions of the limbs are _____ than on proximal body regions.

Back 66

smaller

Front 67

Most neurons are sensitive to ____ submodality of somatic sensation.

Back 67

one

Front 68

Somatotopic representation of the body and face

Back 68

contralateral representation with disproportionately enlarged areas for the face, hand and foot

Front 69

SI cortex: _____representations of the body

Back 69

multiple

Front 70

Multiple maps in different parts of SI: Areas 3a, 3b, 1 and 2. This indicates importance of

Back 70

parallel processing

Front 71

Somatosensory Cortex consist of:

Back 71

SI cortex
Multiple maps
Columnar organization
SII cortex
Other areas may exist (SIII, SIV, etc

Front 72

may be the functional unit of cortical organization.

Back 72

"Columns"

Front 73

___columns of cells have overlapping receptive fields and respond to the same submodality of stimulation

Back 73

Vertical

Front 74

SII cortex: significance is ____.

Back 74

unknown

Front 75

Clinical Features of Lesions in the Dorsal Column System

Back 75

lose precision in discriminative somesthesis. Extent of the deficit is usually proportional to the amount of tissue damage.

Front 76

Clinical Features of Lesions in the Dorsal Column System

Back 76

Increase in two-point threshold
Decrease in vibratory sensitivity.
Decrease in precision of position sense and kinesthesia
Increase in spontaneous pain (possibly due to interaction of this system with the anterolateral system

Front 77

Concept of Pain

Back 77

quantifiable sensory event,
2) An affective component, the reaction to pain; together these 2 components occur

Front 78

the sensation of pain

Back 78

(nociception)

Front 79

Types of Pain

Back 79

Superficial, Fast, Deep, Slow

Front 80

pain - arising from skin and superficial tissues

Back 80

Superficial (cutaneous)

Front 81

pain: short latency, well localized, subsides quickly; has relatively minor affective component

Back 81

Fast (pricking)

Front 82

pain: longer latency, less well localized, longer duration with prolonged "after-discharge"; has strong affective component; difficult to endure.

Back 82

Slow (burning)

Front 83

- arising from deep tissues including visceral organs and muscles, fascia, joints and tendons.

Back 83

Deep pain

Front 84

- sensations of warm and cold; dual system. Better sensor of changing temperature than of static condition.

Back 84

Temperature

Front 85

less "discriminative" than in the dorsal column system

Back 85

Touch -

Front 86

Submodalities of the anterolateral system

Back 86

Pain, Temperature, Touch, Itch, Pressure

Front 87

Submodality: Fast pain
Fiber Type:
Adequate Stimulus:

Back 87

Fiber Type:Ad
Adequate Stimulus:Tissue damage

Front 88

Submodality: Slow pain
Fiber Type:
Adequate Stimulus:

Back 88

Fiber Type: C
Adequate Stimulus: Tissue damage

Front 89

Submodality: Deep visceral pain
Fiber Type:
Adequate Stimulus:

Back 89

Fiber Type: C
Adequate Stimulus: Distention

Front 90

Submodality: Deep somatic pain
Fiber Type:
Adequate Stimulus:

Back 90

Fiber Type:Ad ,C
Adequate Stimulus: Tissue damage

Front 91

Submodality: Temperature
Fiber Type:
Adequate Stimulus:

Back 91

Fiber Type:Ad , C
Adequate Stimulus:Skin temperature and temp. change

Front 92

Submodality Touch
Fiber Type
Adequate Stimulus

Back 92

Fiber Type Ad , C
Adequate Stimulus: Active skin displacement

Front 93

Submodality Pressure
Fiber Type
Adequate

Back 93

Fiber Type Ad , C
Adequate Static skin displacement

Front 94

Submodality Itch
Fiber Type
Adequate

Back 94

Fiber Type C
Adequate Light mechanical stimulation

Front 95

Pain: nociceptors

Back 95

Mechanical nociceptors -
Thermal nociceptors -
Polymodal nociceptors

Front 96

Mechanical nociceptors -

Back 96

high threshold mechanoreceptors

Front 97

Thermal nociceptors -

Back 97

temperatures greater than 45oC.

Front 98

Polymodal nociceptors -

Back 98

respond to mechanical, thermal, chemical energy; anything that causes tissue damage. Indicates that a common mechanism might exist, e.g. the release of a chemical from the damaged tissue that stimulates the receptors

Front 99

Temperature: 2 types,

Back 99

cold and warm.

Front 100

Temperature Mechanism

Back 100

Mechanism probably involves change in the rate of a chemical reaction in the receptor

Front 101

Touch and pressure -

Back 101

same as the other mechanoreceptors (dorsal column types).

Front 102

Itch -

Back 102

unknown mechanism

Front 103

(1st order neurons): ipsilateral projection via the dorsal root to the spinal cord.

Back 103

Primary afferents

Front 104

First synapse in the ipsilateral spinal cord

Back 104

1. Enters substantia gelatinosa
2. May ascend or descend 1 or 2 spinal segments before synapse
3. Synapse is in outer layers of the gray matter of the dorsal horn of the spinal cord.

Front 105

cell body in dorsal horn.

Back 105

Second order neuron

Front 106

Axons cross the midline in the spinal cord to form __________.

Back 106

contralateral anterolateral tract; often called the spinothalamic tract.

Front 107

CNS targets are widespread, accounts for high arousal properties of

Back 107

pain

Front 108

projects to VPL of thalamus and from there to SI and SII. Fast pain, mostly Ad input.

Back 108

Spinothalamic portion:

Front 109

projects to the reticular formation in the brainstem. The reticular formation has widespread connections to cortex and therefore has arousal properties; arousal is important for a pain pathway!

Back 109

Spinoreticular portion:

Front 110

projects mainly to a nucleus known as the periaqueductal gray matter. This nucleus has descending projections to the spinal cord that can reduce pain input from the nociceptors. It also releases endogenous opioid compounds (endorphins and enkephalin) that act as hormones to reduce pain perception.

Back 110

Spinomesencephalic portion:

Front 111

carries these submodalities from the face and head.

Back 111

Cranial nerve input

Front 112

Anterolateral System: Input via _____ myelinated and ______nerve fibers

Back 112

small
unmyelinated

Front 113

Variable topographic representation of the body

Back 113

Spinal cord:
VPL of thalamus:
Reticular formation and other targets in thalamus:
SI and SII

Front 114

Pain and temperature have limited representation in the cortex; somatotopically organized within the sensory homunculus

Back 114

SI and SII:

Front 115

Foot lateral, hand medial (contralateral)

Back 115

Spinal cord:

Front 116

Foot lateral, hand medial; VPM of thalamus:

Back 116

FaceVPL of thalamus:

Front 117

Reticular formation and other targets in thalamus:

Back 117

little or no somatotopic organization

Front 118

Anterolateral System: Large, often ________fields for CNS neurons

Back 118

bilateral receptive

Front 119

Anterolateral System:

Back 119

Older (more primitive) system than the Dorsal Column Pathway
Many neurons are sensitive to more than one submodality of input

Front 120

Functional Properties of the Anterolateral System

Back 120

Input via small myelinated and unmyelinated nerve fibers.

Variable topographic representation of the body.
Large, often bilateral receptive fields for CNS neurons

Front 121

deep visceral pain often referred to superficial skin regions innervated by the same spinal cord segment; convergence may account for this phenomenon. Patterns of referred pain have obvious clinical diagnostic importance.

Back 121

Referred pain:

Front 122

Control of pain input to the CNS - 3 major sources:

Back 122

Interaction with the Dorsal Column Pathway
Efferent (descending pathways)
Endogenous opiod compounds - Endorphins and Enkephalin

Front 123

Interaction with the Dorsal Column Pathway:
Gate Control Theory

Back 123

collaterals of first order fibers of the Dorsal column system can indirectly inhibit pain transmission at its first synapse

Front 124

- nerve fibers from the cortex, reticular formation and other areas can modulate input of pain at all synaptic levels. (Efferent control operates in all sensory systems).

Back 124

Efferent (descending pathways)

Front 125

Endogenous opiod compounds - Endorphins and Enkephalin

Back 125

Stimulation induced analgesia
Release of compounds with morphine-like action
Physiological significance of endorphins and enkephalins.

Front 126

Stimulation induced analgesia

Back 126

profound analgesia can result from electrical stimulation of some brain areas (areas produce endorphins and enkephalin) Substances are released as hormones into the blood--have widespread targets for blocking the reaction to pain; can also act directly as inhibitory neurotransmitters to block pain)

Front 127

(act like morphine: this is the reason opiates have an effect--the brain has receptors sensitive to them

Back 127

Release of compounds with morphine-like action

Front 128

Physiological significance of endorphins and enkephalins.

Back 128

(Important to sense trauma, not to be incapacitated by it, e.g., soldiers with wounds often not aware of injury until later, etc.)

Front 129

Clinical features of lesions in the anterolateral system

Back 129

A. Decrease in pain sensitivity (hypalgesia, analgesia)
B. Decrease in temperature sensitivity

C. Return of pain may occur after lesions of the system

D. Sensory dissociation with spinal cord hemisection (Brown-Sequard Syndrome)

Front 130

This portion will present the structure and function of somatosensory receptors, with special emphasis on the low threshold mechanoreceptors of the skin.

Back 130

Somatosensory receptors:

Front 131

This spinal cord pathway is specialized for transmitting discriminative touch--sensations that are very precise in representing the intensity, location, submodality and timing of stimuli. We will study this pathway from skin receptors through processing in the cerebral cortex.

Back 131

The Dorsal Column System:

Front 132

This system is older phylogenetically, carries pain and temperature in addition to less precise touch and pressure sensations. We will again start at the periphery and carry the information transduced into the CNS and look at the processing of the information, especially pain.

Back 132

The Anterolateral Pathway: