W03_04_Somatosensation beyond the DC/ML

Question 1

name 4 cortical sensory modalities

Answer 1

graphesthesia,
stereognosis,
two-point discrimination,
double simultaneous stimulation

Question 2

name of the receptor that responds to sound, light, tissue damage, temp, touch, pressure?

Answer 2

exteroceptor

Question 3

name of receptor that monitors stimuli from viscera

Answer 3

enteroceptor

Question 4

definition of receptor threshold?

Answer 4

stimulus intensity required to activate the receptor 50% of the time

Question 5

threshold levels for tactile sensation?

Answer 5

low

Question 6

threshold levels for pain?

Answer 6

high

Question 7

function of rapidly adapting receptors?

Answer 7

report the onset/end of a stimulus;

for hi-freq vibration, mvt of objects across skin

Question 8

function of slowly adapting receptors?

Answer 8

report continuously on stimulus;

for pressure, shape, lo-freq vibration, intensity of stimulus

Question 9

size of types of SS nerve fibres?

Answer 9

Aalpha>Abeta>
Agamma>Adelta>
B>C

Question 10

name 3 projections to other areas?

Answer 10

interneurons in dorsal horn (pain suppression);
medullary+pontine reticular formations (alerting responses and modifying locomotor reflexes);
superior colliculus (orienting reflexes)

Question 11

how is sensation focused?

Answer 11

cortical descending inhibition;
lateral inhibition of unrelated interneurons;
these keep modalities separate

Question 12

what are the 4 regions of the SI primary SS area?

Answer 12

cutaneous mechanoreceptors;
proprioceptors;
2x integration for differentiating texture, size, shape, motion

Question 13

what is the SII secondary SS area important for?

Answer 13

tactile memory;

note that SII projects internally to the insula along the gyrus.

Question 14

what are the inputs of SII area?

Answer 14

SI and thalamus;

outputs to temporal lobe via insula

Question 15

where are visual and SS signals integrated?

Answer 15

sensory association area (posterior to postcentral gyrus);

projects to motor cortex for sensory-guided movement