Diverse nonlinear modulation of visual features by retinal amacrine cells

Abstract

SUMMARYInhibitory interneurons are diverse in the nervous system, though most have unknown functions. In sensory systems, two broad classes of computation have been considered – linear effects that generate the classical receptive field and nonlinear modulation that mediates non-classical contextual effects. Here we analyze salamander retinal amacrine cells using a general approach to directly measure and model how an interneuron pathway influences computation. Using simultaneous intracellular and multielectrode recording, we measure the linear feature contributed by an amacrine pathway and nonlinear modulatory effects on other visual features. We find great diversity in the functional effects of amacrine cells, with even apparently simple, linear amacrine cells creating both linear and diverse modulatory effects such as divisive gain control, polarity reversal and shifting threshold on distinct visual features conveyed to single target ganglion cells. The functional effects of amacrine cells parallel the previously noted anatomical and molecular heterogeneity of this interneuron population.HighlightsSome amacrine cells contribute a linear feature to ganglion cells but others do notThe visual feature conveyed by an amacrine pathway improves a ganglion cell modelOne amacrine-ganglion cell pair has different modulatory effects on different featuresAmacrine cells with linear responses have highly diverse nonlinear modulary effects