Temporal sensitivity for achromatic and chromatic flicker across the visual cortex.

We report the temporal sensitivity of human visual cortex across the three canonical post-receptoral channels from central vision to the far periphery. Functional MRI measurements of responses from the LGN, V1, and higher visual cortical areas demonstrate modification of temporal sensitivity across the visual hierarchy. This includes amplification of chromatic signals between the LGN and V1, and a steady increase in peak temporal sensitivity across visual areas beyond area V1. Within V1, we unexpectedly find that peak temporal sensitivity slows in the periphery, especially for achromatic stimuli. Comparison of our results to a model of retinal output demonstrates the substantial post-retinal filtering at work, yielding greater uniformity of responses across area V1 than would be predicted from unmodified retinal signals.