Figure 4. Global stimulus competition in the Ipc.
a) Rasters of unit responses to a dark looming (4 °/s) dot stimulus (Sin), centered in the receptive field, with and without a competing, Sout looming stimulus (8 °/s) presented from different azimuths. b) receptive fields of the unit to the Sin (black) and Sout (gray) stimuli presented alone. Dashed line: center of receptive field. Dotted lines: half-max. c) Response of the unit to the Sin and Sout stimuli presented together as a percent of the response to the Sin presented alone. Red circles: mean ± s.e.m. for Sout locations <15° into the hemifield opposite to the receptive field. Blue circles: mean ± s.e.m for Sout locations ≥ 15° into the opposite hemifield. Dashed and dotted lines: receptive field. d,e) Population average suppression of responses to Sin as a function of the location of the Sout stimulus. Sin = 4 or 6 °/s; Sout = 8 or 10 °/s; n=31; mean ± s.e.m. Sout locations more ≥15° from the receptive field center were binned to the nearest 10° increment. d) Sout locations in azimuth. Red and blue circles, as in c. e) Sout locations in elevation.