This may result in enhanced MUA-LFP check details gamma locking with attention inside the RF, since a unit constitutes a greater proportion of the total MUA if it has a higher firing rate. Thus, one or both of the above-mentioned scenarios likely holds true, i.e., high-rate SUAs might gamma lock disproportionally more with attention and/or strongly gamma locking SUAs might fire disproportionally more with attention. We aimed at investigating whether one of the two scenarios is more prominent. We first tested whether SUAs with high rates show more attentional enhancement of gamma locking. Across SUAs, the stimulus driven firing rate was positively correlated with

the attentional effect on SUA-LFP locking [PPCin – PPCout], Regorafenib datasheet specifically in the gamma band (Figure 7D) (BS: Spearman ρ = 0.44, p < 0.01; NS: Spearman ρ = 0.29, n.s.; all cells: ρ = 0.46, p < 0.001, n = 62). Again, we investigated the effect of baseline and stimulus driven firing rates relative to baseline separately, through multiple regression analysis. Both, a cell’s baseline firing rate (BS: T-stat = 2.86, p < 0.05; NS:

T-stat = 2.42, p < 0.05; all cells: T-stat = 4.29, p < 0.001, n = 62) and baseline corrected firing rate (BS: T-stat = 1.91, p < 0.1; NS: T-stat = 0.87, n.s., n = 21; all cells: T-stat = 2.18, p < 0.05, n = 62), positively predicted the gamma PPC difference between the attention in and out condition [PPCin – PPCout] (Figures 7E and 7F). This effect was again confined nearly to the gamma-frequency band. In agreement with these correlation analyses, a median split of firing rates across the population directly visualized the difference in the attentional effect on gamma locking of the cells. It was negative for the cells with low activity levels (Figure 7G) and positive for the cells with high activity

levels (Figure 7H). Finally, we tested whether also the complementary scenario holds, namely that strongly gamma locking SUAs show more attentional rate enhancements. We found that NS cells that were more strongly gamma locking, had a higher attentional firing rate modulation [FRin/FRout] (Figure 7I; NS: Spearman ρ = 0.47, p < 0.05; BS: ρ = 0.17, n.s.). This discussion is structured in three parts (1) the basic differences between NS and BS cell locking, (2) the diversity in locking phases, and (3) the effects of selective attention. We found that NS cells are almost twice as strongly locked to the LFP gamma rhythm as BS cells. The gamma locking of BS cells is essentially identical to the locking of MUA. To separate isolated single units into putative pyramidal cells and inhibitory interneurons, we used the same approach as many previous studies, clustering cells based on their AP waveforms (e.g., see Mitchell et al., 2007 and Csicsvari et al., 1999).