The large-amplitude depolarizing bumps that occurred at low frequencies in the

complex cell had roughly comparable counterparts in the simple IBET762 cell, but the match between the two waveforms was much less precise than in the complex cell pairs (for example, Figure 1). Overall, the spontaneous activity of two cells had a low correlation (0.4; Figure 7C, left and middle column, black trace), smaller than almost all of the complex cell pairs (Figure 4A). Most of this correlation was due to activity below 20 Hz, since high-pass filtering with a cutoff of 20 Hz removed much of the correlation (Figure 7C, right column, black trace). This result is also reflected in the coherence spectrum for spontaneous activity (Figure 7F, black trace), which shows significant coherence only at frequencies below 20 Hz. We can now ask how Vm synchrony responds to the presentation Apoptosis inhibitor of optimal visual stimulation. During optimal stimulation, spiking activity is largely confined to the column containing these cells. It might be, then, that the cells’ Vm becomes much more correlated. This is not the case, however. Membrane potential responses to preferred (0°) stimulation are shown in Figure 7B (second row). By the definition of simple and complex cells, the temporal patterns of visually evoked

responses in the two cells were very different, the simple cell showing strong modulation of both Vm and spike rate at the stimulus frequency (2 Hz), in contrast to the complex cell which gave an unmodulated response. As in the complex cell pairs, optimal stimulation caused a decrease in the amplitude and width of the

correlation (Figure 7C, first row, left; note that the stimulus component of the evoked response was removed before cross-correlation was calculated). The overall reduction might correspond to a strong decrease in the correlation of the low-frequency components and a weak increase in the correlation of the high-frequency components (Figure 7C, first Astemizole row, right). During visual stimulation, high-frequency components of the complex cell only had a weak correlation with those in the simple cell and the coherence was about one-third of those seen in complex-complex pairs (Figure 7F, compare the coherence value of 0.18 at 20–40 Hz with the coherence of previous complex cell pairs in similar frequency range). Visual stimulation increased the high-frequency Vm power in the simple cell without a distinctive peak in either the Vm power spectrum (Figure 7D, cyan) or the spectrum of relative power change (Figure 7E, top), in contrast to the complex cell. Nonpreferred stimulation (e.g., 270°; Figure 7B, third row) also narrowed the width of the correlation but left the amplitude nearly unchanged (Figure 7C, second row). Two more simple-complex pairs are shown in the Figure S6 (pairs 11 and 12).