Figure 2.

Directional selectivity in the PSPs compared with the spikes. Three example cells comparing directional selectivity in the PSPs with that in the spikes. FM sweep times are shown below the voltage traces. Left, Five individual trials of downward (top) and upward FMs. Fractions are number of spikes per number of trials. Right, Average of all trials illustrates PSP directionality. Spikes were filtered before averaging. Spiking traces (truncated) are in gray. a, Both spikes and PSPs were highly directionally selective in this upward selective cell. RMP was −51 mV. b, Both spikes and PSPs were nondirectional in this nonselective cell. RMP was −58 mV. c, In this downward selective cell, spikes were highly directional, but PSPs were not, illustrating how spike threshold can strongly amplify directional selectivity. RMP was −47 mV.