Figure 2.

Temporally coincident stimuli in the receptive field evoke supralinear spike output and changes in spike timing. A, Optimally oriented bright and dark bars were flashed (128 ms) in 16 positions across the receptive field of a layer 4 simple cell, generating a one-dimensional map. Bar positions A and B were chosen as sites in two discrete receptive field subregions that evoked strong bright and dark responses, respectively. B, Bars A and B each evoked spike output when briefly presented alone (16 ms), but evoked more spikes with a narrower temporal distribution when presented simultaneously. Each example is generated from 10 overlaid traces. C, PSTHs from 30 presentations of A and B alone. D, PSTHs of recorded responses to 30 presentations of A and B together presented at varying interstimulus intervals (black) were compared to predicted PSTHs calculated as the linear sum of the responses to A and B alone (gray). The summed responses were measured within a window bounded by the beginning of the response at an ISI of 0 ms and the end of the responses to A and B alone (dashed line). E, Distributions of the first spike evoked by each of 30 presentations of A and B as a function of their temporal asynchrony.