Although visual stimulation evoked an increase in high-frequency power in both simple and complex cells, it did not cause a strong increase in synchrony. Finally, comparing the distribution of correlation amplitudes between complex-complex pairs and simple-complex pairs for spontaneous and visually evoked activity confirmed the lack of strong Vm correlation for paired simple and complex cells (Figure 7G). Previous literature has suggested that simple cells might be

a relatively heterogeneous group. For example, some simple cells may derive most of their excitatory input from the lateral geniculate nucleus (LGN), whereas some receive most of their input from other cortical cells (Finn et al., 2007). It then seems likely that simple cells become engaged with the complex cell circuits to different degrees. Some simple cells from previous reports, for example, have more high-frequency fluctuations than the ones analyzed here (e.g., Selleck PR 171 Cardin et al., 2005, Cardin et al., 2007 and Gray and McCormick, 1996), although it is still not known to what degree

that these fluctuations were synchronized with those in complex cells. By recording membrane potential (Vm) from pairs of V1 neurons in vivo, we have studied how visual stimulation modulates the correlation of Vm fluctuations between nearby cells. First, high-frequency Vm fluctuations induced by visual stimulation were strongly synchronized. Not only was the synchrony observed between neurons that belonged to the same functional domain, in addition, Dactolisib there was strong synchrony between neurons lying in different functional domains (e.g., Figure 1 and Figure 2). Second, visual stimulation changed the spectral structure of the Vm correlation that was present in the spontaneous state, suppressing coherence at low frequencies (0–10 Hz)

and maintaining or facilitating coherence at high frequencies (20–80 Hz; Figure 1, Figure 2, Figure 3 and Figure 4). Third, for a pair of cells, a broad range of stimuli caused comparable effects on Vm synchrony (Figure 3). Fourth, during visual stimulation, Vm synchrony secondly gave rise to a synchronous form of cross-neuron Vm STA that has an onset preceding the trigger time (Figure 6). Last, in contrast to pairs of complex cells, the high-frequency fluctuations were only weakly synchronized between simple and complex cells (Figure 7). These findings extend the former work (Lampl et al., 1999) by revealing the dependence of Vm synchrony on the stimulus properties, the cells’ stimulus specificity, and the relationship between them. Many intracellular studies in V1 have found that sensory stimulation evokes high-frequency Vm fluctuations (e.g., Anderson et al., 2000, Azouz and Gray, 2008, Bringuier et al., 1997, Cardin et al., 2005, Cardin et al., 2007, Douglas et al., 1991, Gray and McCormick, 1996, Jagadeesh et al., 1992, Priebe et al., 2004 and Volgushev et al., 2003).