OUTCOME ENCODING IN DOMINANT BRAIN-WIDE LATENT DYNAMICS DURING REACHING IS SHAPED BY A DISTRIBUTED NEURONAL SUBPOPULATION

Anticipating the outcomes of actions is central to goal-directed behaviour, but how such expectations are encoded across the brain during ongoing movement remains unclear. To address this, we recorded spiking activity from cortical and subcortical regions using multiple Neuropixels probes simultaneously in head-fixed mice performing a water-reaching task. We found that distributed neural population dynamics were strongly modulated by the availability of reward beyond their encoding of forelimb kinematics. Principal component analysis revealed conserved population dynamics across brain regions and sessions that depended on reach amplitude and reward availability. Generalized linear models revealed outcome-related encoding in region-specific population dynamics, in addition to kinematic encoding, with the strongest outcome signals expressed in cortico-thalamic regions. Unsupervised cluster analysis further identified outcome-encoding subpopulations that were enriched in frontal cortices and disproportionally contributed to the shared global latent dynamics. Together, these findings demonstrate that movement-related population dynamics are shaped by internal, action-mediated outcome expectations, which are embedded in dominant brain-wide latent dynamics during ongoing behaviour.