Thalamocortical mechanisms producing spatial chromatic contrast in mouse V1

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PROJECT SUMMARY The ability to integrate color and form into coherent visual scenes is an important part of our interactions with the environment. This ability is impaired in many ophthalmologic and neuropsychiatric disorders, yet the neural mechanisms responsible for visual feature integration remain understudied. The use of mice as a model organism has provided deep insights into fundamental mechanisms of vison conserved across species and general principles of neural information processing. Recent work in mice has shown that the early mouse visual system is wired to respond to chromatic information and mice can use this information to guide behavior. However, it is unclear how the early visual system integrates spectral and luminance contrasts to represent color spatially. My own preliminary data has demonstrated that neurons in mouse primary visual cortex (V1) can respond to spatial luminance contrast (i.e., form) in a color-dependent manner, building on work demonstrating responses to color contrast in in the lateral geniculate nucleus of the thalamus (LGN) – the preceding stage of visual hierarchy. This suggests that color and form begin their integration through thalamocortical networks, though the exact mechanism of integration is unknown. Thus, the goal of this proposal is to ask how, neurally, are variations in color and luminance integrated to generate spatial chromatic contrast? To do this, I will need to measure responses from a large number of neurons in LGN and V1 to capture the breadth of chromatic responses and relevant connections between regions. Leveraging the relative scale of the mouse visual system and high-density electrophysiology, this project will examine mechanisms of spatial chromatic integration with a high degree of spatiotemporal resolution. Aim 1 will examine the functional convergence of chromatic and achromatic signals from LGN to produce chromatic selectivity in V1. Aim 2 will then examine if and how intracortical networks enhance chromatic selectivity to refine color tuning for subsequent stages of visual processing. In sum, this proposal will expand our fundamental understanding of how the early visual system integrates color and luminance spatially, providing a steppingstone to further experiments investigating how color integrates with specific visual features such as orientation, direction, motion, and ultimately how color is integrated into complex naturalistic scenes. This work will also provide the applicant with invaluable training in his future career as a neuropsychiatrist focused on translating foundational knowledge from computational neuroscience into novel, highly precise therapeutics.