SS - Across-Fiber Coding

Question 1

Selective Adaptation

Answer 1

There are two types of Temperature Receptors (both “Free Nerve Endings”)

Warm Best and Cool Best

Question 2

Warm Best

Answer 2

respond best to stimuli warmer than the skin, and fire faster as temperature increases)

Question 3

Cool Best

Answer 3

respond best to stimuli cooler than the skin, and fire faster as temperature decreases

Question 4

the range of temperatures to which each types responds…

Answer 4

….OVERLAPS with the range of the other

-As a result, temperature coded by the distribution of activity across both types of receptors = “Across fiber coding”

Question 5

Example

physiological zero

Answer 5

about 89oF (32oC) is “physiological zero” (does not feel either cold or hot) = Produces equal response from Warm Best (WB) and Cool Best (CB) receptors - Thus the normal code for 89o
F is “WB = CB” 

• Exposing the skin to a warmer temperature (such as 105o
  F) produces a different code: “WB > CB”

Question 6

Chilling the hand

Answer 6

as by putting it in ice water) will selectively adapt the CB receptors more than the WB receptors, producing an aftereffect such that tepid water (89oF) will now feel warmer (more like 105oF)

• This is because the 89oF water now produces the code normally associated with 105oF (i.e. “WB > CB”)