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

Abstract

Many of our daily actions rely on skilled sequential movements. Sequence performance improves with practice and can reach expert levels with years of repeated practice, truly exemplifying the saying "Practice makes perfect". Human and non-human primate studies have shown structural and functional changes in the primary motor cortex (M1) following extended practice of sequential movements, suggesting M1s involvement in acquisition and retention of skilled sequential movements. However, it has been challenging to causally examine M1s role in sequence learning, because inactivation or lesion of M1 impairs movement production itself. Here, we causally examined M1s contribution to learning of sequential movements by locally inhibiting protein synthesis in M1. Our results show that protein synthesis inhibition in M1 disrupted memory-guided sequential movements at all stages of learning without affecting visually guided reaching, though the effects decreased with continued practice. These findings suggest that neural representations of sequential movements are repeatedly consolidated in M1 through protein synthesis, with the rate of consolidation slowing as learning progresses. TeaserRepetitive practice strengthens neural representations of sequential movements in primary motor cortex of monkeys.