Deciphering the Role of Brainstem Inhibitory Neurons in Visual Motion Processing

The brainstem receives dense retinal innervation and plays vital roles in various visual functions from reflexive behavior to visual perception. Notably, brainstem visual nuclei contain a high percentage of GABAergic inhibitory neurons, which provide both local and long-range inhibition. One such example is the nucleus of optic tract (NOT). This structure is well-known for its sensitivity to global visual motion and its role in mediating the optokinetic reflex (OKR), an involuntary oculomotor behavior essential for retinal image stabilization. Nevertheless, it remains unclear what roles its numerous GABAergic inhibitory neurons play in the OKR and other visual functions. To address this question, we applied a battery of state-of-the-art tools for circuit analysis, including optogenetic perturbations, in vivo/in vitro electrophysiological recording, anatomical tracing, and behavioral assays. In the first half, I will show evidence that NOT inhibitory neurons shape the response properties of NOT excitatory neurons and the tuning of the OKR behavior. In the second half, I will discuss a novel role of inhibitory projections from the NOT to superior colliculus (SC), a brainstem nucleus crucial for visual perception. We discovered that inhibitory NOT-SC projections preferentially respond to global background motion and suppress SC activity and SC-dependent visual perception in such motion context. Overall, our findings provide new insights into the mechanisms of how inhibitory neurons in brainstem circuits contribute to reflexive behavior and visual perception.

Hybrid Zoom link:  https://utoronto.zoom.us/j/82202413099 

To request an individual meeting with the speaker, please contact Kaori Takehara (kaori.nishiuchi@utoronto.ca).

Visit https://www.takeharalab.com/bbseminar for further information.