Ohbayashi, M. | Search bioRxiv

bioRxiv2024

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

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.

neuroscience↗

bioRxiv2019

Inhibition of protein synthesis in M1 of monkeys disrupts performance of sequential movements guided by memory

The production of action sequences is a fundamental aspect of human motor skills. To examine whether primary motor cortex (M1) is involved in maintenance of sequential movements, we trained two monkeys (Cebus apella) to perform two sequential reaching tasks. In one task, sequential movements were instructed by visual cues, whereas in the other task, movements were generated from memory after extended practice. After the monkey became proficient with performing the tasks, we injected an inhibitor of protein synthesis, anisomycin, into M1 to disrupt information storage in this area. Injection of anisomycin in M1 had a marked effect on the performance of sequential movements that were guided by memory. In contrast, the anisomycin injection did not have a significant effect on the performance of movements guided by vision. These results suggest that M1 of non-human primates is involved in the maintenance of skilled sequential movements.

neuroscience↗