Figure 2.

Visual cortex does not seem to support discrete switching at the perceptual sensitivity rate. (A) The impulse response function of V1 estimated through voltage sensitive dye imaging of an awake monkey. A primate was presented with brief (50 ms) presentations of oriented gratings. Responses were averaged, and FIR deconvolution was used to estimate the impulse response function (light grey; black—a smooth-spline approximation). (B and C) The impulse response computed in A can be used to derive a linear approximation of the expected response of the network to arbitrary inputs. Using ideal control signals (stair case modulations—marked in red) the network’s capacity for supporting discrete state switches at varying rates can be assessed. (B) The predicted response of V1 to state switches occurring at 2 Hz exhibits discrete switching (black). The control signal is superimposed in red. (C) The predicted response of V1 to state switches occurring at 20 Hz, a rate that is arguably within the rate at which perceptual content is modulated during perception of movement, shows no trace of state switching.