Adam Kunz¹, Matthew Adusei², Farran Briggs¹; ¹National Eye Institute, National Institutes of Health, ²National Institute of Mental Health, National Institutes of Health

Layer-6 corticothalamic feedback in the visual system has classically been cast as a modulator of first-order thalamic relay cells rather than a source that drives their activity. Yet the role of corticothalamic feedback arising outside primary visual cortex remains uncertain. Recent discoveries of distinct corticogeniculate cell types in V2 and mid-level extrastriate areas in both ferrets and macaques open new avenues for investigating the function of corticogeniculate pathways. Here we asked whether L6 feedback from the extrastriate posteromedial lateral suprasylvian (PMLS) area, implicated in visual motion processing, reshapes responses in the dorsal lateral geniculate nucleus (LGN) in ways that challenge the modulator-only view. Using retrograde viral gene delivery and optogenetics, we selectively and reversibly activated PMLS L6 corticogeniculate neurons in vivo while recording LGN neuronal responses to drifting gratings, bars, flashed spots, and m-sequence white noise stimuli. Activating PMLS feedback systematically shifted LGN neuronal tuning for temporal frequency toward higher values with little change in overall gain, baseline firing, or spike-timing precision. These changes align LGN output with PMLS neuronal preferences for high temporal frequencies, consistent with PMLS’s role in visual motion perception. Together, the results suggest that PMLS corticogeniculate feedback plays a specialized role in configuring LGN sensitivity during early visual processing to behaviorally relevant stimuli, an effect more “driver-like” than purely modulatory. They also provide the first visual system evidence that LGN tuning can be modified through “egocentric selection”, a mechanism previously described for corticothalamic circuits in the auditory and somatosensory systems, whereby thalamic responses align with the tuning preferences of their active cortical inputs.