FIG. 9.

Some inhibitory combination-sensitive interactions may be created by disinhibition of rebound excitation. Delay curve shows suppression of high-frequency spike discharge when the high-frequency sweep is delayed by 6 ms. Dashed line indicates criterion for combination-sensitive inhibition. B: PSTHs show spiking responses to different stimuli. Gray bars indicate the timing of a windowed response. C and D: averaged (n = 3) and individual voltage traces show LO- and HI-evoked transient hyperpolarizations followed by depolarizations. Resting membrane potential = −77 mV. Spike height = 55 mV. See Fig. 2 for protocol. E: graph schematically represents the timing of hyperpolarizations (boxes below the horizontal lines) and depolarizations (boxes above the horizontal lines) responses to the HI and LO frequency sweeps (black and white, respectively). The timing of sound presentations is shown by black (HI) and white (LO) hexagons above the horizontal lines. Hatched rectangles indicate an overlap of HI- and LO-evoked potentials. Inhibited delays are indicated by an asterisk at left. Note that spike suppression occurred when the LO-evoked depolarization was aligned with the HI-evoked hyperpolarization.