Dr. Gautam Awatramani
Canada Research Chair in Synaptic Physiology
University of Victoria
Understanding how neural circuits in the brain compute information not only requires determining how individual inhibitory and excitatory elements of circuits are wired together, but also a detailed knowledge of their functional interactions. Recent advances in optogenetic techniques and mouse genetics now offer ways to specifically probe the functional properties of neural circuits with unprecedented specificity. Perhaps one of the most heavily interrogated circuits in the mouse brain is one in the retina that is involved in coding direction (reviewed by Mauss et al., 2017; Vaney et al., 2012). In this circuit, direction is encoded by specialized direction-selective (DS) ganglion cells (DSGCs), which respond robustly to objects moving in a ‘preferred’ direction but not in the opposite or ‘null’ direction (Barlow and Levick, 1965), which we now know relies on the coordination of three transmitter systems: glutamate, GABA and acetylcholine (ACh). In this talk, I will present an in-depth functional characterization of the direction-selective circuit in the mouse retina. I will present new results demonstrating that these transmitter systems are coordinated on a ‘fine’ subcellular scale, promoting a dendritic 'democracy'. I will argue that such an arrangement enables computations to be made rapidly and with high fidelity even in the presence of confounding noise.