Fig. 4: Simulated visual processing in outer and inner plexiform layers capture empirically observed differences in the effects of horizontal and amacrine cell inhibition on novel object enhancement and population dynamics.

a The circuit modeled in b–d. Photoreceptors (black) combined the visual input with feedback inhibition from horizontal cells (blue). Transient (green) and sustained (red) BCs differed by the formulation of their dependency on the photoreceptor input. b Top, photoreceptor (black) and HC (blue) voltage responses (inverted for presentation purposes) elicited by the visual stimuli. Note the effect of preceding inhibition (blue arrows) that is present during established motion. Bottom, the shapes of the BC potentials for the same stimuli. c The peak amplitude of the simulated visual responses, normalized by the response to the full-field moving bar. In the absence of horizontal feedback, photoreceptor responses were similar across all probed stimuli (open circles and dotted lines). d Enhancement of the emerging object (solid) and the static edge (dotted) as a function of different model parameters. e Top, ACs were included in the simulated circuit. Amacrine cells were stimulated by a separate subpopulation of BCs (gray). Bottom, BC and AC (blue) activation by narrow (diameter = 100 µm, top) and wide (diameter = 500 µm, bottom) spots, used to calibrate the strength of AC surround. Dotted, responses in the absence of inhibition in the inner plexiform layer. f, g as in b, d in the presence of ACs.