Why is it that a blister burn becomes sensitive to light touch and stroking stimuli that are not ordinarily painful?
This phenomenon occurs secondary to sensitization at the level of the dorsal horn.
There, the C-fiber and A-delta nerve fibers conveying painful stimuli converge on second-order neurons that also receive input from A-beta fibers conveying light touch and stroking.
Due to upregulation, the second-order neuron is now likely to depolarize in response to input from neurons conveying nonnoxious stimuli.
