Figure 8.

Attention-related effects on r_noise during spontaneous spiking. Conventions in this figure are same as for Figure 6. Similarly to r_noise measured during stimulus-driven activity (Fig. 6), we found a significant interaction among attention, target r_tuning, and distractor r_tuning. Namely, in pairs with opposite r_tuning signs (A, D), there is higher r_noise when attending the feature with negative r_tuning and lower r_noise when attending the feature with positive r_tuning. We observe one compelling difference between the effect of r_noise during spontaneous spiking and driven spiking: in B (pairs with positive AM and ΔBW r_tuning), we found that attending to AM reduces r_noise during spontaneous spiking, but not during stimulus driven activity. However, the (null) effect observed in C mirrors that observed during driven activity. In E, we reiterate these results using narrower bins. We calculated the average r_noise difference value (attend AM − attend BW) within bins of width 0.33 and then smoothed these binned averages. The matrix in E exhibits similar structure to that in Figure 6E, illustrating similar effects of attention on r_noise during driven and spontaneous spiking. In A–D, inset histograms show the distribution of r_noise in each condition.