Sensory Physiology (Karius)

Question 1

what kind of channels do touch receptors have and what opens them?

Answer 1

sodium channel

opened with deformation of the cell membrane

Question 2

in sensory neurons the start of the action potential is called what

Answer 2

generator potential

Question 3

what are 2 ways to start an action potential

Answer 3

if the stimulus is strong enough or lasts long enough

Question 4

what is the best studied touch receptor

Answer 4

pacinian corpuscle

Question 5

how does the pacinian corpuscle receptor work

Answer 5

when touch something all layers of the membrane are deformed, fluid inside membranes
-leads to opening of mechanosensitive Na+ channels on the membrane and influx of sodium

Question 6

what happens if the stimulus to a touch receptor is maintained

Answer 6

action potential gradually die away as adaption occurs

-due to redistribution of the fluid in the corpuscle

Question 7

what happens with adaption after removal of the stimulus

and what is it called

Answer 7

triggers AP as ending reforms, this is an afterdischarge

Question 8

what is a receptive field

Answer 8

area from which stimulation produces activation of the neuron

Question 9

what are 2 ways to code for intensity of stimulus

Answer 9

number of action potentials

pattern of APs

Question 10

coding stimulus intensity

a change of about ___% is usually required for conscious recognition of the change

Answer 10

10%

Question 11

perceived intensity vs actual intensity depends on what

-2 types

Answer 11

type of sensory receptor

• muscle senses are 1 to 1
• cutaneous is more variable

Question 12

dorsal columns are important for

Answer 12

proprioceptive and discriminative (fine touch)

Question 13

spinothalamic tract is important for

Answer 13

thermal, nociceptive, and coarse touch (less specific)

Question 14

pre-synaptic inhibition, neuron A,B,C

Answer 14

when C is activated it releases GABA which causes Cl- to enter neuron A and hyperpolarize the cell. not as much calcium can now come in and less NT is released from Neuron A
-reduces AP potential in cell B

Question 15

where does pre-synaptic inhibition occur?

-purpose?

Answer 15

between neighboring receptors at the first synapse in their pathway
-increases brain’s ability to localize signal

Question 16

each column in the cortex deals with ____ sensory modality in ___ part of the body

Answer 16

one, one

Question 17

sensory information arrives at what of the 6 layers in the cortex for a column via __

Answer 17

4 via thalamus

Question 18

neighboring coluns receive info from the ____ part of the body but ___ modality

Answer 18

same, different sensroy modality

-ex: copuscle touch and thermoreceptor

Question 19

S1 and S2 damage causes what

Answer 19

if S1 damaged S2 doesn’t work

if S2 damaged, does not affect S1

Question 20

somatic sensory area 1 location

Answer 20

post-central gyrus

broadman’s area 1,2,3

Question 21

somatic sensory area 2 location

Answer 21

wall of lateral fissure

Question 22

S1 function

Answer 22

integration of the information for position sense as well as size, shape discrimination

• not complete
• feeds processing to S2

Question 23

S2 function

Answer 23

required for cognitive touch

• stereognosis
• comparisons between 2 different tactile sensations
• determine whether something becomes a memory

Question 24

parieto-temporal-occipital association cortex required for what
-receives input from where

Answer 24

required for high-level interpretation of sensory inputs

-receives input from diff sensory cortical areas, including S1 and S2

Question 25

PTO functions with the input it receives

Answer 25

naming of objects

analysis of spatial coordinates of self/surrounding objects

Question 26

if an area of the body is amputated or denervated how does the body respond

Answer 26

afferent input from remaining parts of body will reinnervate the cortex
-if not, neurons die

Question 27

how does body respond if area of cortex is lost

what is the trade off?

Answer 27

those afferents will innervate neighboring columns

-localization or specialization is somewhat lost, know what input has hapened but not neccessarily where

Question 28

law of projections

Answer 28

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