CELL-TYPE-SPECIFIC INHIBITION FROM THE VLGN SHAPES VISUAL PROCESSING IN SUBCORTICAL CIRCUITS

Survival in dynamic environments relies on the brain’s ability to rapidly and flexibly process visual threats. The ventral lateral geniculate nucleus (vLGN) is an inhibitory prethalamic structure that has powerful control over fear responses, receives direct retinal input and sends cell-type-specific projections to regions involved in sensorimotor transformations and defensive behaviours, including the superior colliculus (SC), lateral posterior nucleus (LP), and periaqueductal grey (PAG). While recent work has shown that the vLGN modulates visual activity in these downstream targets, the functional contributions of individual vLGN cell types remain unknown.
Here, we performed Neuropixels recordings in awake, head-fixed mice to simultaneously monitor neuronal activity in the SC, LP, and PAG during presentation of diverse visual stimuli, while selectively manipulating specific inhibitory populations in the vLGN. We recorded from hundreds of neurons across these and other regions, with visually tuned units predominantly observed in superficial SC and LP, consistent with previous reports.
Preliminary analyses reveal that optogenetic activation of VGAT⁺ vLGN neurons bidirectionally modulates the firing of visually responsive units, producing both increases and decreases in activity across SC, LP, and PAG. Interestingly, on a population-level these changes in activity resulted in weakened downstream encoding of visual stimulus features that in some cases was reduced to only detection of luminance. Using optogenetics in SOM-, PV-, Penk-, and NOS-Cre mouse lines, we identify distinct effects of individual vLGN cell types on downstream visual processing. Ongoing analyses will further characterize how these cell-types shape visual tuning in downstream circuits.