Abstract

At ARVO 1989 we presented amplitude and phase data for macaque retinal ganglion cells to a temporal stimulus. Our stimulus presented 2000-td equiluminant red and green LEDs in temporal sine wave modulation. We measured ganglion cell responses as a function of physical phase difference between the LEDs. P-pathway (tonic) cells could be described by a linear model of the LWS and MWS cone inputs. M-pathway (phasic) cell behavior was more complicated. Phasic ON- and OFF-center cells showed similar amplitude behavior as a function of physical phase angle that paralleled psychophysical data for the same stimulus. The data suggested evidence of compound center-surround inputs: centers show (LWS + MWS) cone summation while surrounds show cone opponency and can be Red-On or Green-On. The phasic cells showed differing phase patterns. Some phasic cells showed a phase response dominated by L cones while others showed evidence of a phasic response dominated by M cones, giving four different phase patterns: ON-center with LWS cone phase, OFF-center with MWS cone phase, ON-center with MWS cone phase and OFF-center with LWS cone phase. The first two could be fit by an (LWS + MWS) center with an opponent surround that showed a fixed 90° phase shift, predicted by the quadrature nature of the stimulus. The other pair of phasic cells could also be predicted by a (LWS + MWS) center and an opponent surround. However, the surround phase was 180° with respect to the center. All cells show a small center-surround latency.

© 1989 Optical Society of America