Figure 4.
Spatial profile of the effect of a visual competitor on responses to a visual stimulus centered in the RF. A, Azimuthal tuning: responses and best-fit Gaussian profiles of an OTi-d site to single looming stimuli presented at different azimuths. S1vis (loom speed = 8°/s, black) and S2vis (speed = 14°/s, blue). Positive (negative) azimuths represent locations contralateral (ipsilateral) with respect to the recording site. The data indicate mean ± SEM. B, Elevational tuning: responses and best-fit Gaussian profiles for the same site as in A. Positive (negative) elevations represent locations above (below) the visual plane. C, Top, Azimuth-response profile for paired looming stimuli. Site exhibited a pronounced effect in the presence of S2vis. Responses to S1vis and S2vis presented simultaneously as percentage changes (mean ± SEM) with respect to the responses to the S1vis stimulus presented alone. S1vis was presented at the RF center, while S2vis was presented at various azimuths outside the RF. Asterisks indicate significant response suppression (p < 0.05, see Materials and Methods). Bottom, Schematic diagram showing the stimulus configuration for two extreme S2vis locations. D, Top, Elevation-response profile for paired looming stimuli. Site exhibited a pronounced effect in the presence of S2vis. Same conventions as in C.