Grant: Project Grant

Vision begins in the retina, where neurons do far more than simply relay images to the brain. One of the most important visual features extracted at this early stage is the direction of motion, which allows us to detect moving objects and navigate our environment. Understanding how this computation occurs is essential for revealing how the brain processes visual information and how these processes may fail in disease. A key cell type involved in motion detection is the starburst amacrine cell, a retinal neuron with a distinctive star-shaped structure formed by many radiating branches. These cells the earliest neurons in the visual system that respond selectively to the direction of motion. Using chemical signals they precisely control the activity of downstream neurons and transmit motion information to higher centers in the brain. Despite decades of research, it remains unclear how starburst amacrine cells compute motion direction within their dendrites or why the coordinated release of both excitatory and inhibitory signals is necessary. Earlier theories proposed that this computation depends on asymmetric wiring or external inhibitory circuits, but experimental evidence has not supported these models. More recent findings from our laboratory indicate that direction selectivity arises locally within individual dendritic branches, suggesting that intrinsic electrical mechanisms play a central role. This research will identify the cellular and biophysical processes that enable starburst amacrine cells to detect motion direction. Specifically, we identify the novel expression of a specialized voltage gated potassium channel (Kv family) in starburst. We will further characterize this channel and show how it shapes direction-selective responses in starbursts. By revealing how single neurons perform sophisticated computations, this work will advance our understanding of visual processing and provide insight into disorders in which motion perception is impaired.