Thalamic circuit diversity for active visual processing

Conscious image perception depends on the dorsolateral geniculate nucleus (dLGN) of the thalamus. The dLGN receives signals from the retina and sends its outputs to the primary visual cortex. Already at this first central stage, the brain actively modulates vision by attention and arousal. Yet, the circuit mechanisms for processing and actively modulating visual information in the dLGN are largely not known. Cells and circuits in the dLGN show diverse specializations, which can only partially be explained by known parallel streams of information. I here propose to explore the role of thalamic circuit diversity for visual processing and its active modulation, using cutting-edge technologies at multiple scales, from synapses to long-range connections, that will dissect and interrogate thalamic circuits at unprecedented resolution in the mouse model. I propose novel approaches that will advance beyond the current state of the art.First, we investigate how retinal input diversity functionally transforms into thalamocortical visual feature diversity. Second, we study how diverse modes of inhibition by local interneurons – powerful key players with supposedly multifaceted roles – contribute to the diversity of thalamocortical outputs. Third, we explore how diverse extraretinal inputs influence visual processing and interact during active behavior. Key outcomes will be: (1) the retino-thalamic transformation matrices, (2) a multi-mechanistic model of local inhibition, (3) a spatial map and causality model of different extraretinal inputs. These approaches will provide missing links between input and output diversity that can redefine the role of thalamus. Beyond approaching the question how cognition is implemented, ActiVisTha will have translational and technological impact: understanding the circuits for early visual processing and its active modulation will promote the development of advanced visual prostheses for the blind as well as machine learning technologies.