Motor cortex flexibly deploys a high-dimensional repertoire of subskills

Area of Science:

• Neuroscience
• Motor Control
• Systems Neuroscience

Background:

• Skilled motor behavior relies on combining multiple subskills.
• The neural mechanisms underlying this versatility in the motor system are not fully understood.

Purpose of the Study:

• To investigate the dimensionality and flexibility of neural activity in the primary motor cortex (M1) during complex motor tasks.
• To understand how M1 contributes to the flexible combination of subskills for skilled movement.

Main Methods:

• High-density Neuropixels recordings were used in macaques performing a challenging force-tracking task.
• Analysis focused on neural dynamics and population-level activity patterns in M1.

Main Results:

• M1 activity was found to be significantly higher-dimensional and more flexible than previously assumed.
• Neural dynamics reflected transitions across multiple dimensions and computations, even for a single-task degree of freedom.
• Distinct neural locations and dimensions were associated with different behavioral control strategies, sometimes used compositionally.
• Population-level factors selectively activated for specific dynamics, indicating subskill-specific neural engagement.

Conclusions:

• M1 exhibits a highly flexible and high-dimensional neural system for skilled motor behavior.
• Neural activity in M1 is dominated by the engaged subskill, allowing for diverse representations even with similar motor output.
• Findings challenge traditional views of M1's role, revealing a more versatile computational capacity.