EFFECTS OF STIMULUS FREQUENCY AND INTENSITY ON HABITUATION AND SENSITIZATION IN ACUTE SPINAL CAT

Habituation and sensitization of the flexor withdrawal reflex (tibialis anterior muscle) were studied in acute spinal cat as a function of stimulus intensity and frequency for frequencies ranging above 1 2 sec. The following relationships were consistently observed: (1) habituation is an exponential decline in response amplitude which occurs as a function of iterated stimulation of cutaneous afferents. In some instances habituation may be described as linear over much of its course; (2) habituation occurs more rapidly and to a greater degree of response decrement for higher frequencies of stimulation; (3) habituation is more pronounced for low intensities of stimulation than for high intensities, and; (4) sensitization occurs as a response increment with repetitive stimulation of cutaneous afferents under certain circumstances and may show two distinct time courses, short-term and long-term sensitization. These two phenomena may be differentiated on the basis of stimulus intensity, frequency and their interaction. © 1969.