Gradual consolidation of skilled sequential movements in primary motor cortex of non-human primates

Expert-level performance of sequential movements can be achieved through extensive practice. The primary motor cortex (M1) is suggested to play a key role in acquiring and retaining sequential movements, with evidence of reorganization in M1 following prolonged practice, such as changes in fMRI activation in humans and altered neuron activity in monkeys. Here, we examined the timeline of plastic changes in M1 of monkeys during learning of sequential movements. A challenge in studying a role of M1 in learning is that its inactivation impairs movement, masking learning processes. To address this, we used a protein synthesis inhibitor to disrupt memory consolidation in M1 during learning. Our results show that inhibiting protein synthesis in M1 disrupted memory-guided performance at all stages of learning, though the effect decreased with continued practice. This suggests that neural traces for sequential movements are repeatedly consolidated through protein synthesis, with the rate of consolidation slowing as learning progresses.