Understanding the neuronal substrates of flexible visual processing in everyday life

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"Visual processing has mostly been studied in static conditions in which subjects (humans or animal models) do not move. While in these conditions the basic elements of visual processing have been established, we know surprisingly little about visual processing in more natural conditions, in which the subjects move around their natural environments. Over the last decade studies in rodents, fishes, flies and humans provided robust evidence indicating that motor actions have major effects on neural activity in the visual system and indicating that visual processing is heavily controlled by the behavioral state of the subject. This new scenario is consistent with anatomical data indicating that only a small fraction of synaptic inputs to visual thalamus comes from the retina, while the rest is constituted by projections from cortex and other thalamic and brainstem nuclei. We currently have a good understanding of the retinal projections, but we know little about all the non-retinal projections that modulate visual processing according to behavioural states."Our research aims to address these major gaps in our understanding of visual processing in natural, real-life conditions. More specifically we address four questions: 1) What informations about behavioural state are conveyed to the visual thalamus?2) How informations about behavioural states are integrated with the incoming visual information? What is the effect of such integration on visual processing? 3) What is the source of these information? Which brain areas provide which type of information? 4) How and to what extent behavioural information in visual thalamus affects action selection in subsequent behaviors? To do that, we will take advantage of our ability to measure 3D motor actions in freely behaving animals [1], combined with simultaneous brain recordings (as in [2] but from high-throughput ~1000 channel Neuropixel electrodes [3]) and optogenetic stimulation of well-defined cell types. The anatomical projections to the visual thalamus will be further characterized by combining injections of Brainbow viruses in mice with single cell reconstruction of axonal projections in whole brains [4] using our in house-built computational analysis platform.The student will be trained in acute and chronic (freely moving) electrophysiology, in vivo optogenetics, circuit tracing through viral injections and confocal microscopy, computational methods for analyzing behavior and neuronal activity. The project will be a close collaboration between Dr Riccardo Storchi lab (main supervisor), Profs Timothy Brown and Rasmus Petersen labs and Dr Nina Milosavljevic