Figure 2.

Effects of the varying the voltage threshold on the representation of cortical responses. (A) An example of the raw voltage waveform is shown in grey, plotted in units of standard deviation around its mean value of 0. Red lines indicate integer multiples (1–5) of the standard deviation (σ) below the mean. The lower trace shows the voltage waveform on an expanded time axis. (B) The grey voltage traces in each panel show examples of threshold crossing events for voltage thresholds from 1–5σ below the mean. The black curves indicate the average voltage waveform for threshold crossing events at each threshold, and the numbers above each panel indicate the associated threshold crossing rates (Hz). (C) The black curve describes how the population-averaged threshold crossing rate declines as the voltage threshold becomes increasingly distant from the mean. The gray curves show the mean results for each stimulus type. (D) The black curve shows how the average interval between successive threshold crossing events increases as the voltage threshold becomes increasingly different from the mean. The gray curves show the mean results for each stimulus type.