Eye-head coordination during goal-directed orienting in mice
In afoveate species such as mice, it is accepted that gaze is typically redirected by head movements with a saccade-and-fixate strategy, while the eyes primarily stabilize vision within a limited oculomotor range. This view suggests that the accompanying eye movements are primarily reflexive, driven by mechanisms like the vestibulo-ocular reflex (VOR). However, emerging evidence challenges this assumption, suggesting that eye movements during active head motion may not be purely reflex-driven. Here, we directly test whether eye movements in mice are actively coordinated as part of voluntary gaze redirection rather than being reflexive. By systematically monitoring head and pupil positions during goal-directed orienting in a cohort of male mice, we find that mice generated active saccadic eye movements whose onsets are tightly linked to head movements. Furthermore, these saccadic eye movements occur at markedly shorter latencies than reflexive quick-phase eye movements evoked by comparable passive head rotations. Importantly, the interplay between coordinated eye and head movements during voluntary orienting resemble the predictable, stereotyped gaze patterns seen in foveate animals, such as primates. Our results suggest that mice possess an evolutionarily conserved mechanism for gaze redirection, integrating voluntary eye-head coordination similar to that of foveate vertebrates. These findings reframe the prevailing view by demonstrating an actively coordinated eye-head component to gaze redirection under goal-directed conditions in mice, complementing established reflexive mechanisms.