Fig. 11.

X-projecting HVc neurons exhibit inhibition that is strongly evoked by forward but not reverse BOS playback.A, A direct comparison of z-scores for subthreshold hyperpolarizations (net negative area, measured with respect to spontaneous hyperpolarizations in a 1.5 sec window before the stimulus) evoked by forward (x-axis) versus reverse (y-axis) BOS playback is shown. Pairedt tests indicate that membrane hyperpolarization was more strongly evoked by forward BOS playback (n = 20 cells; p value shown aboveplot). B, Within-cell comparisons of subthreshold hyperpolarizing selectivity (d′ negative area) and firing-rate selectivity (d′ firing rate) for forward over reverse BOS playback show that the two measures are equally biased toward forward BOS playback (n = 20 cells; p value from paired t test shownaboveplot). The unityline represents equivalent subthreshold and suprathreshold selectivity, whereas the graybars demarcate zones of nonselective subthreshold (horizontal) or firing-rate (vertical) responses. Note that these relationships contrast with those for response strength and selectivity measured for depolarizing subthreshold responses and firing rate in X-projecting neurons (see Fig. 7).