Modulation sensitivity of ganglion cells in peripheral retina of macaque.

There is ample psychophysical evidence that flicker is more salient in the peripheral than the central visual field, but the physiological basis of this eccentricity-dependant change is unclear. Here, we compared responsivity to temporal modulation of ganglion cells in central and peripheral primate retina. Above 30 Hz modulation frequency, both magnocellular (MC) and parvocellular (PC) pathway cells are more responsive in peripheral retina. This suggests that an increase in high-frequency temporal responsiveness arises in outer retina before the MC and PC pathways diverge. In both central and peripheral retina, the critical fusion frequency of MC cells is higher than that of PC cells. This result is consistent with other evidence that psychophysical flicker sensitivity is mediated by the MC pathway.