somatosensory system

Question 1

mechanoreceptors

Answer 1

sensitive to bending, stretching, pressure, or vibration

Question 2

what are the 4 specialized nerve endings

Answer 2

• merkel’s disk
• meissner’s corpuscle
• pacinian corpuscle
• ruffini ending

Question 3

what are the 4 qualities of a stimulus that are endoded by our sensory system

Answer 3

• modality
• location
• intensity
• duration

Question 4

what are the 5 sensory modalities

Answer 4

• vision
• hearing
• touch
• taste
• smell

each with submodalities

Question 5

awareness of ____ ____ depends on spatial distribution of activated receptors

Answer 5

spatial aspects

Question 6

what is intensity signaled by

Answer 6

signaled by firing rate

Question 7

what is duration signaled by

Answer 7

signaled by time course of response

Question 8

what is the receptive field of a receptor

Answer 8

the space within the receptive sheet in which the sensory receptor is located and in which it transduces stimuli

Question 9

RF of mechanoreptor

Answer 9

certain area of skin where it can transduce pressure or vibration

Question 10

what is the gradient of sensitivity within the receptive field

Answer 10

highest in the center and progressively lower toward the periphery

Question 11

the frequency of action potentials is proportional to the ____ of the stimulus

Answer 11

intensity

Question 12

neurons tell us something about stimulus ____ and ____

Answer 12

location and intensity

Question 13

what is duration

Answer 13

adaptation to prolonged stimulation

Question 14

meissner’s corpuscle adaptation and receptive field size

Answer 14

rapid; small

Question 15

pacinian corpuscle adaptation and receptive field size

Answer 15

rapid; large

Question 16

merkel’s disk adaptation and receptive field size

Answer 16

slow, small

Question 17

ruffini’s ending adaptation and receptive field size

Answer 17

slow, large

Question 18

most 2nd order neurons have ____ ____ in their RFs which enhances spatial resolution

Answer 18

surround inhibition

Question 19

spatial resolution: two-point discrimination

Answer 19

best for body regions with the highest innervation density and amount of cortical area devoted to them: e.g. fingers and lips

Question 20

spinal segments

Answer 20

spinal nerves within the divisions of the spinal cord

Question 21

what does each spinal segment provide

Answer 21

sensory innervation to a particular region of the skin

Question 22

dermatome

Answer 22

the area of skin and deeper tissues innervated by a single dorsal root

Question 23

DC-ML first neuron

Answer 23

large myelinated axons of dorsal roots that carry proprioception and touch modalities into the cord

Question 24

touch, vibration, conscious proprioception information ascends through:

Answer 24

• dorsal columns (spinal cord)
• dorsal column nuclei (medulla)
• medial lemniscus (brainstem)
• ventral posterior nucleus (VPL, thalamus)
• primary somatosensory cortex, S1

Question 25

nociceptors

Answer 25

* mediate transduction of pain * activated by stimuli that could cause tissue damage * free nerve endings

Question 26

thermal receptors

Answer 26

* mediate transduction of cold, cool, warm and hot * free nerve endings

Question 27

spinothalamic tract first neuron

Answer 27

* small diameter axons of dorsal roots that carry pain and temperature modalities into the cord * they all synapse with sensory neurons in the dorsal horn

Question 28

what synapses in the substantia gelatinosa of dorsal horn

Answer 28

A and C afferents

Question 29

decussate and travel up the cord in the ____ tract to the thalamus, VPL, and then to S1

Answer 29

spinothalamic

Question 30

the trigeminothalamic tract (dorsal trigeminal tract)

Answer 30

* touch, vibration * CN V, from face to main sensory nucleus of V

Question 31

the trigeminothalamic tract (ventral trigeminal tract)

Answer 31

* pain, temperature * spinal trigeminal tract * spinal trigeminal nucleus

Question 32

somatotopic map in S1 of contralateral body

Answer 32

neighboring receptors in skin send information to neighboring cells in VPL/VPM which send information to neighboring cells in S1

Question 33

damage to somatosensory cortex results in:

Answer 33

contralateral sensory deficits

Question 34

somatotopic map of facial vibrissae in mouse SI

Answer 34

* sensory signals from each vibrissa follicle go to one cluster of SI neurons called a "barrel" * barrel cortex in SI

Question 35

areas 3b and 1

Answer 35

cutaneuous stimuli

Question 36

areas 3a and 2

Answer 36

proprioceptive stimuli from muscles and joints

Question 37

functional columns in neocortex

Answer 37

* found within the somatopic map * neurons with same modality from pia to white matter * slowly adapting neurons * rapidly adapting neurons

Question 38

the posterior parietal cortex

Answer 38

* involved in somatic sensation * analysis of "where" things are from visual inputs

Question 39

agnosia

Answer 39

inability to recognize objects

Question 40

astereognosia

Answer 40

loss of **stereognosis**: the ability to perceive the form of an object by using the sense of touch

Question 41

neglect syndrome

Answer 41

part of body or part of world is ignored

Question 42

parietal neglect in dogs

Answer 42

* don't eat half the bowl of food * run into things on neglected side * circling