Hageter, J. | Search bioRxiv

bioRxiv2022

Thalamic regulation of a visual critical period and motor behavior

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.

neuroscience↗

bioRxiv2021

Environmental and molecular modulation of motor individuality in larval zebrafish

Innate behavioral biases such as human handedness are a ubiquitous form of inter-individual variation that are not strictly hardwired into the genome and are influenced by diverse internal and external cues. Yet, genetic and environmental factors modulating behavioral variation remain poorly understood, especially in vertebrates. To identify genetic and environmental factors that influence behavioral variation, we take advantage of larval zebrafish light-search behavior. During light-search, individuals preferentially turn in leftward or rightward loops, in which directional bias is sustained and non-heritable, and maintained by a habenula-rostral PT circuit. Here we use a medium-throughput recording strategy and unbiased analysis to show that significant individual to individual variation exists in wildtype larval zebrafish turning preference. We classify stable left, right, and unbiased turning types, with most individuals exhibiting a directional preference. Raising larvae at elevated temperature selectively reduces the leftward turning type and impacts rostral PT neurons, specifically. Exposure to conspecifics, variable salinity, environmental enrichment, and physical disturbance does not significantly impact inter-individual turning bias. Pharmacological manipulation of Notch signaling and carrying a mutant allele of a known Notch pathway affecter gene, gsx2, disrupted turn bias individuality in a dose-dependent manner. These results establish that larval zebrafish is a powerful vertebrate model for inter-individual variation with sensitivity to specific environmental perturbations and gene dosage.

neuroscience↗