Active gaze behavior organizes V1 activity in freely-moving marmosets

Abstract Human and nonhuman primates rely heavily on vision to actively explore and navigate their environment. Although primate visual cortex has been studied extensively in head-fixed animals, little is known about how the primate visual system supports natural, active vision in freely moving animals. Here, we address this gap in the primary visual cortex (V1) by leveraging a head-mounted eye-tracking system while simultaneously recording the activity of ensembles of single V1 neurons in freely moving marmosets. Our results reveal that primate neural activity is tightly driven by visual input and organized by the temporal structure of natural gaze behavior, and these gaze-related responses are largely abolished in the absence of visual input. We further show that distinct phases of gaze movement, i.e. rapid redirection (gaze shift) and subsequent stabilization (fixation), engage separable suppression and enhancement of the V1 responses. The enhancement during fixation was clearly linked to visual input. Moreover, the amplitudes of naturally-occurring gaze shifts organize RF input across successive fixations, and adaptively shapes fixation-associated enhancement. These findings define the dynamics in V1 that link natural gaze behavior and stimulus-driven responses in freely moving primates. The work opens a previously inaccessible but fundamental regime of primate vision and establishes freely moving paradigms as a foundation for understanding real-world visual processing during ethologically relevant behaviors. Significance Statement Vision in everyday life unfolds through active exploration that continuously reshapes the visual input reaching the brain. Yet nearly all we know about primate visual cortex derives from head-fixed paradigms that constrain these natural dynamics. Here, we present the first study of neuronal activity in primate primary visual cortex (V1) during fully unconstrained, freely moving visual exploration. We show that natural gaze behavior dynamically structures visual input and that V1 activity remains tightly anchored to visual signals during active exploration. By establishing freely moving primate paradigms as essential for understanding how vision operates in real-world conditions, this work provides a critical foundation for a more complete account of visual processing in the human and nonhuman primate brain.