Motion Sensitivity in Center-Surround Receptive Fields of Primate Retinal Ganglion Cells

Abstract

Primate visual perception is built on the 20-25 parallel pathways in the retina that carry infor-mation of the visual world to the rest of the brain. Each parallel pathway is represented by a unique type of primate retinal ganglion cell, the outputs of which are formed by a collection of upstream retinal circuits. While each primate retinal ganglion cell type maintains its own unique function, all retinal ganglion cells share a common receptive field structure: an excitatory center enveloped by a suppressive surround. The center-surround receptive field functions to enhance spatial structures likes edges, and in some ganglion cell types contributes to the encoding of color and temporally modulated inputs. Visual motion is well studied across many cortical and subcortical regions of the primate visual system, but our knowledge of how visual motion affects encoding properties of retinal ganglion cells is limited. This thesis aims to characterize visual motion sensitivity in a subset of primate retinal ganglion cell types from the perspective of the classical center-surround receptive field. Our results fall along two major themes. First, that the receptive field centers of some ganglion cell types are far more sensitive to motion of approaching objects than receding ob- jects (Chapter 2). Second, in some ganglion cell types, the presence of motion in the receptive field surround shifts the center-surround relationship from antagonistic to facilitatory (Chapter 3 and 4). Our work suggests that neural inputs to primate retinal ganglion cells are activated dynamically as visual contexts shift, particularly for contexts that involve visual motion. Overall, we demonstrate that the primate retina has the computational complexity required for motion sensitivity that was previously considered to be present only in the primate cortex.