EMERGENT LOCOMOTION-RELATED SIGNALS DOMINATE TUNING OF PRIMARY VISUAL CORTICAL NEURONS DURING LINEAR DISPLACEMENT

We have shown that spiking activity in mouse VISp increases during passive translation and that these signals are vestibular in origin. At the single-cell level, a substantial fraction of neurons exhibit translation speed tuning, and at the population level, translation and visual signals combine through arithmetic summation. Despite the fact that most of the visual motion experienced by an observer arises from movements of the head, the extent to which vestibular signals influence visual tuning properties has not been investigated. Here, in head-restrained mice, we performed Neuropixels recordings from VISp neurons while presenting random-phase texture stimuli (Motion Clouds) with temporal frequencies (TF) up to 7.3 Hz. An agnostic approach, whereby the best of five nonlinear models could be used to optimally fit the tuning profiles, showed that 35/70 cells were accurately fitted and exhibited significant TF tuning. Only 2/35 TF-tuned neurons preserved their original tuning profile during passive translation whilst experiencing the same visual motion stimuli. In contrast, 27/33 neurons were best fitted either by an alternative tuning model (20/33) or by the same model with different parameters (7/33). In 6/33 cases, TF tuning was substantially diminished during translation. The remaining 50% of recorded VISp neurons showed significant tuning during translation and congruent visual flow and not when the head was kept stationary. The majority of VISp neurons therefore exhibited unique tuning profiles that emerge from interactions between visual input and translation signals and are likely to dominate ‘visual responses’ during linear excursions.