s.). Thus, while the majority of neurons fired reliably around CP673451 their individual preferred gamma phase, we found that different neurons fired at strongly divergent preferred gamma phases. Further, NS cells are more synchronized individually to the LFP gamma cycle, yet do not fire more synchronously as a population than the BS cells. This gamma phase diversity contrasted with the diversity in alpha phases. Figure 4C suggests that the distribution of BS cell prestimulus alpha phases

is much less dispersed than the distribution of BS cell sustained stimulation gamma phases (Figure 4A), despite similar alpha and gamma locking strengths and higher spike counts (that de-noises the phase histograms) during the sustained stimulation period. Indeed, BS cells’ alpha network-PPC was reduced by only ∼35% (2.1 × 10−3 ± 0.31 × 10−3 versus 3.0 × 10−3 ± 0.48 × 10−3, p < 0.05, bootstrap test, n = 33) relative to the delay-adjusted network-PPC, indicating that BS cells tended to fire at the same alpha phase

(Figure 5B). While the BS cells’ delay-adjusted network-PPC did not differ between the gamma and alpha GDC-0973 clinical trial frequency, the network-PPC was almost an order of magnitude larger for the alpha- than for the gamma-band (0.54 × 10−3 ± 0.24 × 10−3 versus 3.8.10−3 ± 0.68, n = 18, p < 0.001, bootstrap test). In other words, although BS cells are individually equally synchronized to the LFP gamma and alpha cycle, they fire more coherently as a population in the alpha-band. The high alpha network-PPC for BS cells contrasted

with the low alpha network-PPC for NS cells, indicating a larger degree of alpha-phase differences between NS than between BS cells. One factor that may have contributed to the observed diversity in preferred gamma phases across units is variability in LFP phases across electrodes. To compare the diversity Mannose-binding protein-associated serine protease in LFP phases across electrodes with the diversity in preferred spike-LFP phases across single units, we defined a spike-LFP phase homogeneity measure (Supplemental Experimental Procedures), which assessed to what extent the spike phases relative to one LFP were coincident (in phase) with the spike phases relative to the other LFPs and is defined in analogy to the network-PPC. We then averaged these spike-LFP phase homogeneity values across single units and compared them to the delay-adjusted spike-LFP phase homogeneity values. We found little diversity of LFP phases in comparison to the homogeneity in spike-LFP phases across units, although the observed spike-LFP phase homogeneity was reduced by a factor of ∼35%–40% relative to the delay-adjusted spike-LFP phase homogeneity (Figure 5C), consistent with Maris et al. (2013). We conclude that the diversity in LFP phases across electrodes was relatively low and thereby unlikely to contribute substantially to the observed diversity in spike-LFP phases across single units. The diversity in preferred spike-LFP phases may be a function of spatial distances between units.