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MOVEMENT NEUROSCIENCE EXAM 1 > MODULE 4- Touch + Proprioception > Flashcards

MODULE 4- Touch + Proprioception Flashcards

1
Q

how are mechanical forces on the skin conveys to the CNS

A

via an array of somatosensory affect neurons

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2
Q

what is reflected by the wide variety of mechanical forces that can impinge on the skin

A

the comparably diverse array of mechanoreceptors embedded in the skin

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3
Q

2 types of skin

A

-glabrous
-hairy

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4
Q

**glabrous skin

A

-found on the soles of heads, feet, lips
-capable of highly discriminative touch

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5
Q

**hairy skin

A

-covers 90% of the body
-capable of both discriminative + non-discriminative touch

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6
Q

somatosensory afferent neurons (2)

A

-mechanoreceptors
-dorsal root ganglion

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7
Q

**mechanoreceptors

A

-detect innocuous (harmless) mechanical stimuli impinging on the skin
-transduce mechanical forces into neural signals
-serve as the path by which signals reach the CNS

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8
Q

**dorsal root ganglion

A

pseudo-unipolar neurons soma with a bifurcating axon with one branch from the PNS + the other to the CNS

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9
Q

trigeminal ganglia/nerve

A

sensory receptors for the face

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10
Q

**dermatome

A

the territory innervated by each spinal nerve
-aka each fiber of the cell is from a single dorsal root ganglion

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11
Q

do dermatological maps vary?

A

yes, they vary among individuals

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12
Q

how do dermatomes maintain sensation

A

they overlap significantly for touch, pressure, + vibration so that injury to one set of dorsal root doesn’t result in a complete loss of sensation

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13
Q

what are the sensations where dermatomes do not overlap

A

pain + temperature

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14
Q

how do somatosensory afferent neurons vary

A

vary widely in
-size
-conduction
-velocity
-types of stimuli to which they respond
-response properties

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15
Q

which afferent sensory neurons have the smallest diameter + slowest velocity

A

pain + temperature

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16
Q

which afferent sensory neurons have medium diameter + medium velocity

A

cutaneous mechanoreceptors

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17
Q

which afferent sensory neurons have the largest diameter + fastest velocity

A

muscle spindles

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18
Q

where else are muscle spindles used

A

balance

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19
Q

**receptive fields

A

the area of the skin surface that results in the firing of APs when touched/activated

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20
Q

**how is size of receptive field determined

A

by the amount of branching of the afferent axons

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21
Q

**what test determines size of receptive field

A

2-point discrimination test

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22
Q

**2-point discrimination test

A

-uses calipers to measure
-distinguishing closer together is harder than far apart

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23
Q

**somatic acuity

A

how sensitive each region is
-region-specific
-some body parts are more sensitive than others

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24
Q

why are some body parts more sensitive than others

A

due to overlapping receptive fields in the former

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25
Q

more sensitive body parts

A

-fingertips
-lips

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26
Q

less sensitive body parts

A

-thigh
-back

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27
Q

**slowly adapting afferents

A

fire continuously for as long as the stimulus is occurring

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28
Q

what information do slowly adapting afferents provide

A

information about the size + shape of the stimulus
-ex: carrying a heavy object

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29
Q

**rapidly adapting afferents

A

fire when the stimulus starts + sometimes when the stimulus stops

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30
Q

what information do rapidly adapting afferents provide

A

information about the movement of a stimulus
-ex: the feel of clothing on your body

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31
Q

what do slowly adapting afferents look like on graph

A

spaced out

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32
Q

what do rapidly adapting afferents look like on graph

A

small rapid blips

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33
Q

what do specialized cells types in the skin do

A

transduce unique aspects of touch information

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34
Q

**4 classes of mechanosensory end organs

A

-merkel cells
-meissner’s
-pacinian
-ruffini corpuscles

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35
Q

**free nerve endings

A

afferent nerve fibers lacking specialized receptor cells
-aka there are none of the mechanosensory end organs listed above in free nerve endings

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36
Q

what are free nerve endings important for

A

pain detection

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37
Q

layers of skin (superficial to deep)

A

-epidermis
-dermis
-subcutaneous layer

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38
Q

what are found in the epidermis (3)

A

-free nerve endings
-meissner corpuscle
-markel cell-neurite complex

39
Q

what is found in the dermis (1)

A

ruffini corpuscle

40
Q

what is found in the subcutaneous layer (1)

A

pacinian corpuscle

41
Q

**merkel cells

A

-highest spatial acuity
-smallest receptive field
-slowly adapting
-detect points, edges, curves (i.e., shape + textures)

42
Q

**meissner’s

A

-high density close to skin surface
-rapidly adapting on-off responses
-larger receptive field than merkel cell
-respond to low-frequency vibrations
-detect motion, like the slippage of an object

43
Q

**pacinian

A

-located deep in dermis
-rapidly adaptive
-low response threshold
-have large receptive fields because they’re so sensitive
-detect vibration

44
Q

**ruffini

A

-least understood
-maybe slowly adapting
-respond to skin stretch
-located deep in the skin
-helps provide information about finger position

45
Q

sensory transudction from the skin involves what

A

converting mechanical forces into electrical signals

46
Q

sensory transduction

A

converting the energy of a stimulus into an electrical signal

47
Q

**receptor potential

A

depolarizing current resulting from a stimulus opening an ion channel in afferent nerve endings

48
Q

**what channels do merkel cells have

A

piezo2 ion channels

49
Q

**piezo2 ion channels

A

open as a result of mechanical stimuli

50
Q

proprioception involves sensing forces in what 3 things

A

-muscles
-joints
-connective tissue

51
Q

mechanoreceptors for proprioception (2)

A

-muscle spindles
-golgi tendon organs (GTOs)

52
Q

**proprioception

A

involves information about position of the limbs + body

53
Q

**muscle spindles

A

consist of 4-8 INTRAFUSAL MUSCLE FIBERS surrounded by a capsule of connective tissue

54
Q

**what changes do muscle spindles detect

A

changes in muscle length
-muscle stretch

55
Q

**how do muscle spindles convey information to CNS

A

sends information via group 1a + 2 afferents

56
Q

how does density of muscle spindles vary

A

by muscles

57
Q

**where are golgi tendon organs (GTOs) found

A

in tendons

58
Q

**what changes do GTOs detect

A

changes in muscle tension

59
Q

**how do GTOs convey information to CNS

A

sends information via group 1b afferents

60
Q

**joint receptors

A

mechanoreceptors embedded in joints
-3 types
-signal positions near joint ROM limits

61
Q

what conveys different aspects of somatosensory information to the brain

A

a variety of neural pathways

62
Q

which pathways convey tactile information (sense of touch)

A

spinal cord pathways
-dorsal columns

63
Q

**gracile nucleus + tract is medial/lateral

A

medial

64
Q

**gracile nucleus + tract conveys what information

A

information about lower body (lower limbs)

65
Q

**cuneate nucleus + tract is medial/lateral

A

lateral

66
Q

**cuneate nucleus + tract conveys what information

A

information about upper body (neck, trunk, upper limbs)

67
Q

main ascending touch pathway (lower extremity)

A

(ipsilateral until crossover)
lower extremity ->
dorsal root ganglion (DRG) ->
gracile nucleus ->
CROSSOVER ->
ventral posterior lateral nucleus (VPL) ->
S1

68
Q

main ascending touch pathway (upper extremity)

A

(ipsilateral until crossover)
upper extremity ->
dorsal root ganglion (DRG) ->
cuneate nucleus ->
CROSSOVER ->
ventral posterior lateral nucleus (VPL) ->
S1

69
Q

how does upper extremity differ from lower extremity main ascending touch pathway

A

-upper is the same process but more laterally (lower more medial)
-upper will synapse with cuneate nucleus of brainstem

70
Q

main ascending touch pathway (face)

A

(ipsilateral until crossover)
face ->
trigeminal nucleus ->
principal nucleus ->
CROSSOVER ->
ventral posterior lateral nucleus (VPL) ->
S1

71
Q

**trigeminal nerve (V)

A

tactile information from the head + face

72
Q

what nerve provides somatosensation of the face

A

trigeminal nerve (V)

73
Q

trigeminal nerve enters brainstem + sends information to ____

A

trigeminal brainstem complex

74
Q

**principle nucleus

A

site where most afferents carrying information from cutaneous LTMRs terminate

75
Q

central pathways conveying proprioceptive information (2)

A

-lower body
-upper body

76
Q

**lower body central pathway to convey proprioceptive information

A

proprioceptive afferents ascend via clarke’s nucleus ->
dorsal spinocerebellar tract ->
ipsilateral cerebellum

77
Q

**upper body central pathway to convey proprioceptive information

A

proprioceptive afferents ascend via dorsal column nuclei (external cuneate nucleus) ->
ipsilateral cerebellum

78
Q

thalamic neurons (2)

A

-VPM
-VPL

79
Q

**VPM

A

transmits somatosensory information carried by the trigeminal system from the face

80
Q

**VPL

A

transmits somatosensory information by the rest of the body

81
Q

**how is the primary somatosensory cortex mapped

A

somatotopically
-homunculus reveals that the sensitivity of a body part is proportional to the AMOUNT of somatosensory cortex receiving input from that body part
-for both sensation + motor control

82
Q

how is homonculus scaled

A

size represents how mcuh area is dedicated to each region

83
Q

primary somatosensory cortex

A

-S1 neurons respond to a variety of tactile features, such as texture, orientation, velocity, direction, speed
-must know where a limb is in space + that type of sensory information to be able to move it

84
Q

how do corticocortical connections process somatosensory information

A

establish a functional hierarchy for processing of somatosensory information

85
Q

what pathways are beyond S1 (primary somatosensory cortex)

A

-corticocortical pathway
-descending pathway

86
Q

what does S1 do in parietal areas

A

projects to parietal areas where information derived from proprioceptive afferents signaling the current state of muscle contraction gains access to circuits that initiate voluntary movements

87
Q

what are corticocortical + descending pathways critical for

A

integration of sensory + motor information

88
Q

there are more ascending/descending projections

A

far more descending
-we have no idea why

89
Q

central representations of the body are ____ + ____

A

-plastic
-modified by experience

90
Q

plasiticity

A

our brain is adaptable + can change based on experiences

91
Q

plasticity in the adult cerebral cortex

A

somatosensory cortex representations of each body part changes in response to experiences of the person

92
Q

example of plasticity in the adult cerebral cortex

A

the amount of cortex represented by the 3rd finger will be invaded by adjacent cortical areas, such as that innervated by the 2nd + 4th fingers, if the 3rd is lost (amputated)

-monkey example

93
Q

___ leads to greater cortical reprsentation of that body part

A

increased used of a body part (ex: finger,hand, etc)

MOVEMENT NEUROSCIENCE EXAM 1 (9 decks)

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