(A) Responses of an example neuron with two peaks (same data as in Figure 4B). (B) Responses of an example neuron without two peaks (same data as in Figure 4D). (C–D) Response predictions of a linear model (dotted lines) and the residuals (solid lines), derived from the responses in (A–B), as described below. Responses to stimuli at different occlusion levels were modeled as gain modulations of responses to unoccluded stimuli (black lines) using the following equation. where r is the response as a function of occlusion level u and time t. k is a scalar value that specifies the response gain. For each occlusion level, we estimated k using a linear regression between the responses to occluded and unoccluded stimuli in the interval 65–150 ms. For the V4 neuron whose responses are shown in A, the predicted responses provide a good match to the observed responses and the residuals are low. This implies that the neuron’s temporal response profile is similar across occlusion levels up to a multiplicative scale factor, and that the dynamical response has a stereotypic trajectory with a single input parameter k(u). This result suggests that the dependence of this neuron’s responses on occlusion level is governed by its earliest input signals and that this relationship is stationary during the test stimulus epoch. For the V4 neuron whose responses are shown in (B), the predicted responses do not provide a good match to the observed data. The residuals are large and positive: they reach a maximal value around 150 ms, and are strongest for intermediate occlusion levels. Thus, a good minimal description of the dynamical response trajectories can be obtained by including an additive term that is stronger for occluded than unoccluded stimuli. Specifically. where f(u,t) is given by the residual (in D). This result is consistent with the possibility that the additive input given by f(u,t) is derived from vlPFC inputs because f(u,t) emerges (~150 ms) after response onset in roughly half the PFC neurons, and that f(u,t) is stronger for responses to occluded than unoccluded stimuli as in vlPFC.