Theory 62/Itching/Threshold lens
Scratching Needs a Gain Threshold
The claim
Scratching is triggered above a threshold in the ratio of itch signal to inhibitory tone, so a strong descending inhibition can suppress the reflex entirely.
01Mechanism
The scratch reflex competes with inhibitory control; the ratio determines whether the reflex is released.
02Prediction
Scratching should track the ratio.
03Refutation
Scratching tracking itch intensity would remove inhibition.