Fig. 4.
Time course and frequency dependence of PSP depression. PSPs were elicited by stimulating the lateral lemniscus with temporal sequences, of 1 sec duration and 2 sec intersequence interval, of pulses. Within each sequence, pulse trains (100 Hz) consisted of nine, five, or two pulses, repeated at rates of 5, 10, or 20 Hz, respectively. For each neuron, PSP amplitudes were normalized with respect to the largest (mean) PSP recorded for each stimulus condition. Open squares are data from 5 Hz stimulation data, filled squares are from 10 Hz data, andfilled circles are from 20 Hz data. The time (x-axis) of occurrence of the first PSP in response to the stimulus was designated the 0 point. Means and SEs are plotted (n = 11).