Figure 7.
Effect of attention on firing rates, on the exponent of the expansive nonlinearity, and on the ensuing changes in the FF. A, Example case in which attention causes a systematic reduction of the exponent of the expansive nonlinearity (red and blue curves), but has either a small effect on firing rate increases (blue vs red dots) or has a more substantial effect on firing rate increases (blue vs red squares). B, Effect of the changes shown in A on the FF. C, Systematic exploration of attentional effects on the FF (color coded are FF difference between attend-RF and attend-away conditions) for different attentional rate modulations (relative to precue activity; assumed to be 50 spikes/s, x-axis) and different attentional reductions on the expansive nonlinearity (the exponent of the Variance = mean ratex, y-axis). Attention-induced activity differences (attentional modulation) were assumed to occur in 2 spikes/s steps.