Fatigue in cat facial mechanoreceptors

Mechanoreceptor fatigue, the reduction in number of impulses with repeated presentations of the same mechanical stimulus, was studied in facial hairy skin of the cat. We found that the variables that influence the magnitude of fatigue are, in order to importance: stimulus duration, interstimulus interval and stimulus amplitude. We also found that in about 40% of all mechanoreceptors studied, phentolamine, an alpha-noradrenergic antagonist, produced periodic reversal of fatigue and in some cases produced an increase in spontaneous firing.