The Spatiotemporal Precision of Ganglion Cell Signals: a Comparison of Physiological and Psychophysical Performance with Moving Gratings

Comparison of the spatiotemporal information delivered by ganglion cells with human psychophysical performance may give insight to how retinal information is utilized by cortical mechanisms, and constrain models of spatiotemporal processing. Ganglion cells' responses were measured with drifting gratings of various spatial and temporal frequencies and contrasts. The spatiotemporal precision of cell responses was estimated in terms of a noise measure and phase variation, and compared to human vernier performance. Noise and phase variation of magnocellular (MC) cells was least at low temporal frequencies, despite their transient responses. The patterns of spatiotemporal precision of MC cells resembled the patterns of human vernier thresholds while those of parvocellular cells did not, implying use of MC cells' signals in these tasks. The analysis further implied that cortical mechanisms must perform a sophisticated spatiotemporal analysis over local ganglion cell arrays.