Tuesday, 4-19-Cutaneous Senses/Sensory Physiology (Karius)

Question 1

In sensory neurons, depolarization is called a ___

Answer 1

generator potential

-if the stimulus is strong enough or last long enough, the generator potentials will cause the afferent neuron to come to threshold and generate an AP

Question 2

The ___ is a receptor that responds to touch and comprised of alternating layers of membrane with fluid between them surrounding the nerve ending

Answer 2

pacinian corpuscle

Question 3

when we touch something, all of the layers of the pacinian corpuscle membrane are deformed which leads to the opening of ___ channels on the membrane and influx of ___ which generates AP’s back to the CNS. If a stimulus is maintained, the AP’s gradually die away as ___ occurs

Answer 3

• mechanosensitive Na+ channels
• Na+
• adaptation

Question 4

in some cases of receptor adaptation, the removal of the stimulus triggers APs as the ending “reforms”. This is known as an ___

Answer 4

afterdischarge

Question 5

After removing my sunglasses from my face after wearing them for several hours, I reach for them even though I am no longer wearing them. This is an example of ___

Answer 5

afterdischarge–> associated with the persistence of the sensation after the stimulus eliciting the discharge has been removed

Question 6

Regarding sensory neurons:

___ is the sensory nerve and all of it’s branches

___ is the area from which stimulation produces activation of the neuron

Answer 6

sensory unit

receptive field

Question 7

Regarding the relationship between perceived strength and actual (measured) intensity:

___ senses: are close to 1 –> our perceived intensity matches the actual (measured) intensity very closely

___ senses: are more variable –> what we perceive may diverge from the actual rather substantially

Answer 7

muscle senses

cutaneous senses

Question 8

This pathway to the brain conveys proprioceptive and discriminative (fine) touch: ___

Answer 8

Dorsal columns

Question 9

This pathway to the brain conveys thermal, nociceptive, and coarse touch: ___

Answer 9

spinothalamic tract

Question 10

what is the end result of pre-synaptic transmission?

Answer 10

reduced NT release from the inhibited pre-synaptic terminal

Question 11

a “normal” chemical synapse has NT release from Neuron A to the dendrite of Neuron B. A new neuron comes in, Neuron C, and synapses on Neuron A by releasing the NT ___ which then activates ___ entrance into Neuron A. This causes the pre-synaptic terminal of Neuron A to hyperpolarize and allows less ___ to enter which leads to less NT release from Neuron A and ultimately decreasing the probability of an AP in Neuron B

Answer 11

GABA

Chloride

Calcium

Question 12

Pre-synaptic inhibition occurs between neighboring receptors at the __ synapse in their pathway. This increases the brain’s ability to localize the signal.

Answer 12

first

Question 13

The sensory cortex is arranged ___

Answer 13

somatotopically

Question 14

Neurons in the somatosensory cortex are arranged in __ and each one of these deals with 1 sensory modality in 1 part of the body

Answer 14

columns

Question 15

Sensory information arrives at its respective column in layer ___ via the thalamus

Answer 15

4

Question 16

___ is in the post-central gyrus, Brodmann’s 1, 2 and 3, is the 1st stop for most cutaneous sense, and its somatotopic representation is: toes=medial, head=lateral

Answer 16

Somatic Sensory Area 1 (S1)

Question 17

___ is in the wall of lateral (sylvian) tissue, receives input from S1, and gives somatotopic representation (not as detailed as S1)

Answer 17

Somatic Sensory Area 2 (S2)

Question 18

___ is involved in the integration of the information for position sense as well as size, shape discrimination. Processing of information in this area is NOT complete

Answer 18

S1

Question 19

___ is required for ‘cognitive touch’, stereognosis, comparisons between 2 different tactile sensations, and determining whether something becomes a memory

Answer 19

S2

Question 20

Damage to S1 will have what affect on S2?

Damage to S2 will have what affect on S1?

Answer 20

• Damage to S1 will impair the functioning of S2

- Damage to S2 will not impair the function of S1

Question 21

The ___ association cortex is required for high-level interpretation of sensory inputs. It receives that input from the different sensory cortical areas, including S1 and S2

Answer 21

parieto-temporal-occipital (PTO)

Question 22

The __ functions in the analysis of spatial coordinates of self/surrounding objects, naming of objects, and many other functions related to other aspects of cognition

Answer 22

PTO

Question 23

if an area of the body is amputated (or otherwise denervated), what happens to the area of the cortex that received sensory info from the amputated region?

Answer 23

afferent input from remaining parts will reinnervate that part of the cortex

Question 24

if an area of the cortex is lost, what happens to the afferents that innervated that region of the cortex?

Answer 24

the afferents will innervate neighboring (remaining) columns

Question 25

The doctrine of specific nerve energies states that stimulation of a sensory pathway at any point leads to the perception of a sensation that is dictated by __

Answer 25

the nature of the receptor that started the pathway -if i stimulate the cortical column that receives input from a pacinian corpuscle, i will perceive the sensation of light touch

Question 26

The __ states that no matter where along the path we stimulate it, the perceived sensation is always referred back to the area of the body in which the receptor is located

Answer 26

law of projections -if the cortical column i stimulated receives input from a pacinian corpuscle in my left index finger, i perceive the touch as occurring on my left index finger