Cortico-subcortical interactions via the thalamic reticular nucleus for visual adaptive sensing

点击翻译按钮获取中文摘要

Mammalian vision relies on a hierarchy of neural processing stages, which involve multiple loops between cortex, first- and higher-order visual thalamus, and the visual sector of the thalamic reticular nucleus (visTRN). The TRN, famously known as the "guardian of the gateway to the cortex", is a major source of inhibition for thalamic nuclei, and can thus exert powerful control over thalamic activity at different spatiotemporal scales. In vision, for instance, sensory signals passing through the lateral geniculate nucleus of the dorsal thalamus (dLGN) are substantially transformed, which likely requires versatile inhibitory control. Beyond sensory visual processing, versatile inhibitory control might also be required for other, well-known effects of visTRN: modulation of thalamic responses by behavioral state, and attentional selection. The existence of complex inhibitory mechanisms is supported by recent discoveries of subnetworks within visTRN: groups of genetically defined neurons that are topographically and physiologically distinct, and connect with first- and higher-order visual thalamic nuclei. How these visTRN subnetworks contribute to visual sensory processing, how their responses depend on cortico-fugal inputs, and how they shape thalamic activity in the context of behavior, is currently unknown. Here, we propose to address these questions by combining state-of-the art in vivo electrophysiological recordings, optogenetic manipulations for cell-type specificity and input mapping, viral tracing, behavior, and computational analyses. Specifically, we will focus on three objectives. In Objective 1, we will investigate how subpopulations of visTRN neurons differentially represent visual information. In Objective 2, we will determine, with subnetwork resolution, visTRN’s corticofugal inputs, and how responses in the subnetworks are shaped by feedback from visual cortex. In Objective 3, we will measure the activity of these subpopulations of visTRN neurons in the context of behavior, and investigate the dynamics of visTRN responses during learning of a visual task. The proposed project promises to advance our understanding of how the visTRN contributes to image-forming vision and ultimately adaptive sensing. More generally, it will reveal how intricate cortico-subcortical loops shape visual sensory processing in the context of behavior.