2 point disrimination

Question 1

what is somatotopy

Answer 1

the correspondence of receptors in parts of the body via respective nerve fibres to specific functional areas of the cerebral cortex

Question 2

describe receptove field overlap

Answer 2

a single stimulus is percieved in one receptive field - there is no indicator of its location in that field

with overlapping fields - if stim lies in the overlapping area - stimulate the 2 fibres in different proportions - therefore CNS can determine the exact location

Question 3

describe how sensory convergence relates to 2 point discrimination

Answer 3

many primary sesory neurons converging into a single secondary neuron = large receptive field

when fewer neurons converge secondary receptive fields are smaller - 2 stimuli activate separate pathways and are percieved as distinct stimuli

Question 4

summarise lateral inhibition *

Answer 4

primary neuron response is proportional to stimulus strength

pathway closest to stimulus inhibits neigbours

inhibition of lateral neurons enhances perception of stimulus

Question 5

what is the density of receptors on the palmer surface of the finger tips and back of finger

Answer 5

palmer - 60 pain, 100 touch receptors

back of finger - 100 pain, 9 touch receptors

Question 6

what are the clinical uses for 2-point discrimination

Answer 6

test for nerve damage eg cut nerve, and recovery

test for diseases of the nervous system

test for nerve recovery after repair

two point discrimination lower in T2DM

Question 7

effect of age on 2 point discrimiunation

Answer 7

it gets worse - less able to discriminate 2 points