Test 2: lecture 15 somatosensory

Question 1

___ are sensitive to bending, stretching, pressure or vibration

Answer 1

mechanoreceptors
Specialized nerve endings: Merkel’s Disk, Meissner’s corpuscle, Pacinian Corpuscle, Ruffini ending

Question 2

___ are receptors specialized for proprioception

Answer 2

muscle spindles
golgi tendon organ

Question 3

4 qualities of a stimulus

Answer 3

modality (vision, hearing, touch taste, smell and their submodalities)

location

intensity

duration

Question 4

rapidly adapting neurons

Answer 4

fire at the onset and stop of a stimulus

vibration sensors

Question 5

slow adapting receptors will ___

Answer 5

fire continuously

(touch, light touch, deep touch, pressure)

Question 6

Awareness of spatial aspects depends on ____ of activated receptors

Answer 6

spatial distribution

Question 7

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

Answer 7

receptive field of a receptor

Question 8

____ certain area of skin where it can transduce pressure or vibration

Answer 8

receptive field of mechanoreceptor

Question 9

There is a gradient of ____ within the receptive field

Answer 9

sensitivity

-highest in the center and progressively lower toward the periphery

Question 10

receptive field has a gradient of sensitivity meaning ____

Answer 10

there will be more AP created when you touch the center of a receptive field then when you touch the edge

Question 11

The frequency of Action Potentials is proportional to the ____ of the stimulus

Answer 11

intensity

press harder = more AP

light touch= less AP

Question 12

what does it mean when neuron will adapt to a prolonged stimulus

Answer 12

at first a stimulus will trigger a bunch of AP

but over time the AP will decrease

it will take the neuron some time to return to normal

Question 13

___ receptors small field size and rapid adapation

Answer 13

meissner’s corpuscle

Question 14

___ receptors have large receptive field size and rapid adaptation

Answer 14

pacinian corpuscle$

Question 15

____ receptors have slow adaptation and small receptive field size

Answer 15

merkel’s disk

Question 16

___ receptors have large receptive field size and slow adaptation

Answer 16

ruffini’s ending

Question 17

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

Answer 17

surround inhibition

will turn off neighbor

Question 18

a high innervation density mean ____

Answer 18

you can detect two points at a smaller range

(more detail)

hands have a higher innervation density then the back

Question 19

what is it important for 2nd order neurons to have surround inhibition

Answer 19

makes detecting two points easier

improves two point discrimination

Question 20

two point discrimination is best for body regions with the ___ innervation density and amount of cortical area devoted to them

Answer 20

highest

fingers have many nerves in a small area and can detect the difference between two points at a smaller distance then somewhere with less density like the back

Question 21

•Each___ provides sensory innervation to a particular region of the ski

Answer 21

spinal segment

Question 22

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

Answer 22

dematome

Question 23

dorsal column medial lemniscal tract

Answer 23

3 neuron path for touch, pressure and proprioception for the limbs

1st neuron is large myelinated axon will come through the dorsal root, synapse on the dorsal root ganglion and will split and contribute to reflexes in the ventral horn and branch up the spinal cord up the dorsal funiculus (FC or FG)to the dorsal column nuclei (NC or NG) in the medulla, cross sides and up by the medial lemniscus to the VPL of the thalamus , then up to the S1, primary somatosensory cortex of the cerebral cortex

Question 24

Dorsal Trigeminothalamic tract

Answer 24

touch and vibration for the head

receptor in the face and head in through the trigeminal nerve, synapse on the main sensory nucleus of CN 5, cross sides up to the VPM of the thalamus, then up to S1 -primary somatosensory cortex

Question 25

nociceptors

Answer 25

mediate transduction of Pain

activated by stimuli that could cause tissue damage

free nerve endings

TRP receptors (Activate _T_ransient _R_eceptor _P_otential ion channels)

Question 26

___ are pain and thermal receptors

Answer 26

_T_ransient _R_eceptor _P_otential ion channels (TRP)

free nerve endings

Question 27

thermal receptors

Answer 27

Mediate transduction of cold, cool, warm and hot

free nerve endings → _T_ransient _R_eceptor _P_otential ion channels (TRP)

Question 28

spinothalamic tracts

Answer 28

pain and temp from body

get info from TRP receptors (nociceptors for pain and thermal receptors for temperature), come in through the dorsal root on small lightly myelinated axons and synapse in the substantia gelatinosa of the dorsal horn, cross sides and travel up the lateral ventral column as the lateral spinothalamic tract all the way up to the VPL of the thalamus, synapse and then up to the S1- somatosensory cortex

Question 29

where does the 1st neuron of the spinothalamic tract synapse

Answer 29

substantia gelatinosa of the dorsal horn

pain and temp from body

Question 30

ventral/spinal trigeminothalamic tract

Answer 30

(ventral trigeminal tract)

pain and temp for the head

in through the trigeminal ganglion at mid pons, down the spinal trigeminal tract to the caudal medulla, synapse at the spinal trigeminal nucleus, back up to the VPM in the thalamus, then up to the S1 somatosensory cortex

Question 31

lesions in the S1 leads to losses on what side of the body?

Answer 31

opposite side

Question 32

Sensory signals from each vibrissa follicle go to one cluster of SI neurons called a ____

Answer 32

barrel

Question 33

S1 primary somatosensory cortex are divided into what brodmann’s area?

Answer 33

2 and 3a: proprioceptive stimuli from muscles and joints

1 and 3b: cutaneous stimuli

Question 34

area 1 and 3a :

Answer 34

cutaneous stimuli

carries info to the secondary somatosensory cortex → amygdala and hippocampus

Question 35

Area 3a and 2

Answer 35

carriers proprioceptive stimuli from muscle and joints

3a → secondary somatosensory cortex → amygdala and hippocampus

3a→2

2→ parietal areas 5 and 7 → to motor and premotor cortical area

2→secondary somatosensory cortex → amygdala and hippocampus

Question 36

functional columns in the neocortex

Answer 36

neurons from the same modality line up with each other within the somatopic map

slowly adapting vs rapidly adapting neurons

Question 37

cortical map plasticity

Answer 37

if an area of cells no longer receive input/are dead, the cells around them will take over that territory

maps are dynamic

adjust depending on the amount of sensory experience

Question 38

posterior parietal cortex

Answer 38

involved in somatic sensation

analysis of “where” things are from visual inputs

Question 39

inability to recognize objects

Answer 39

agnosia

Question 40

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

• Can you tell a quarter from a nickel by just feeling it in your pocket?

Answer 40

astereognosia

Question 41

asterognosia

Answer 41

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

• Can you tell a quarter from a nickel by just feeling it in your pocket?

issue with the posterior parietal cortex

Question 42

neglect syndrome

Answer 42

part of body or part of world is ignored

caused by issues with the posterior parietal cortex

Question 43

three issues from posterior parietal cortex lesions

Answer 43

Agnosia – inability to recognize objects

Astereognosia

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

• Can you tell a quarter from a nickel by just feeling it in your pocket?

Neglect syndrome – part of body or part of world is ignored