Fig. 3.

Paired-pulse depression evoked by white matter stimulation is not accompanied by a change in fiber volley amplitude.A, Superimposed traces are responses to the first stimulation pulse (left) and the second stimulation pulse (right) for a complete ISI series (from 20 to 2560 msec). Traces were recorded before (black) and in the presence of 10 mmkynurenic acid (red). Arrowheads indicate the fiber volley. B, Graph summarizing the effects of PPS on the amplitude of the FP (open symbols) and on the FV (filled symbols). The FP and FV were recorded either simultaneously (circles; n = 18) or before and after bath application of kynurenic acid (triangles; n = 15). Stimulation was applied to the white matter.