Fig 8. Phasic selectivity is driven by slope detection.

(A) Tonic models responded to the level of excitation in the driving current. Spiking activity aligned well to the moments when net excitation was greater than zero, and the model produced jittery, unreliable responses to broad peaks of excitation. Blue segments of the trace mark when the convolution is positive. (B) Phasic models responded primarily when driving current contained a positive slope with a high rate of change. Spike times aligned well to these slopes. The red segments of the convolution mark the times at which the difference of the smoothed convolution was 1.5 standard deviations above the mean difference. Because such slopes were relatively scarce and brief, the spikes predicted by the phasic model were selective and had little temporal variation.