Thalamic regulation of a visual critical period and motor behavior

Summary During the visual critical period, sensory experience refines the structure and function of visual circuits. The basis of this plasticity was long thought to be limited to cortical circuits, yet recently described thalamic ocular dominance plasticity challenges this dogma and demonstrates greater complexity underlying visual plasticity. Yet how visual experience modulates responses of thalamic neurons or how the thalamus modulates CP timing is incompletely understood. Using a novel larval zebrafish, thalamus-centric ocular dominance model, we show functional changes in the thalamus and a role of inhibitory signaling to establish critical period timing using a combination of functional imaging, optogenetics, and pharmacology. Moreover, hemisphere-specific functional changes in genetically defined thalamic neurons correlate with changes in visuomotor behavior, establishing a role of thalamic plasticity in modulating motor performance. Together, our work demonstrates that visual plasticity is more broadly conserved and shows that visual experience leads to neuron-level functional changes in the thalamus that require inhibitory signaling to establish critical period timing.