Spike timing in response to pulsatile stimuli. PSTH and phase histograms for 2 example neurons that did not change firing rates in response to the stimulus (different from the one shown in Fig. 2). Neuron 1 displays good time locking to the stimulus pulses, while neuron 2 does not. The inset for neuron 1 shows 3 example spikes relative to stimulus pulse onsets during the first presentation of the 30 Hz stimulus.