Manifold properties in the macaque medial premotor cortex during switching from attending to tapping to a metronome

Animals synchronize their movements with external rhythms to coordinate perception and action, but the neural population mechanisms that allow them to attend and then initiate and sustain these rhythms remain unclear. Using high-density recordings from the medial premotor cortex (MPC) of two macaque monkeys, we investigated neural dynamics during an attend-then-synchronize tapping task with visual metronomes. We found low-dimensional neural manifolds that capture neural population trajectories. During the attention phase, trajectories exhibited increasing amplitude and oscillatory modulation along successive stimuli, consistent with a resonant-like mechanism. Transition to tapping was marked by a reliable shift into a distinct manifold subspace, enabling accurate decoding of the switch in behavior. In addition, large amplitude and oscillatory indices were higher in successful tapping synchronization trials than in incorrect ones. These findings demonstrate that macaque MPC activity evolves along smooth, low-dimensional trajectories whose geometry governs different perceptual and motor aspects of tapping synchronization.