Approaching Visual Perception with Spatiotemporally Patterned Optogenetic Stimulation

Visual inputs evoke dynamic changes in the responses of visual neurons that evolve over both space and time. All visual experiences must somehow stem from stimulus-evoked spiking patterns in visual brain regions, but determining which neurons and periods of activity causally give rise to perception is one of the grand challenges in neuroscience. Targeted manipulations of neuronal activity while subjects perform sensory tasks have been indispensable for probing computations underlying perception. However, limits on the spatiotemporal precision of neuronal perturbations have constrained the scope of inquiry. Recent advances in optogenetic stimulation approaches have opened the door to augmenting neuronal activity on the spatiotemporal scales of visual computations. Applications of patterned optogenetic stimulation in behaving subjects have revealed many important insights into how different aspects of visual neuronal responses contribute to perception and ultimately behavior. First, we survey optical tools for precise optogenetic perturbations in mice and monkeys. Next, we discuss how patterned optogenetic experiments in behaving subjects have been used to causally test the neural mechanisms underlying perception. Last, we highlight a few key areas that we believe will be important for continued progress in this emerging research area.