Selective direct motor cortical influence during naturalistic climbing in mice

Area of Science:

• Neuroscience
• Motor Control Research
• Computational Neuroscience

Background:

• Understanding how the motor cortex directly controls limb muscles via descending projections is crucial for deciphering motor control mechanisms.
• Current knowledge on the precise timing and pathways of this influence remains incomplete.

Purpose of the Study:

• To investigate the direct influence of the forelimb primary motor cortex (caudal forelimb area, CFA) on limb muscles during an ethologically relevant behavior.
• To identify neural activity patterns in the CFA that correlate with specific muscle activation and behavioral output.

Main Methods:

• Mice were trained to perform an ethologically inspired climbing behavior.
• Neuropixels recordings were used to capture neural activity in the CFA.
• Muscle activity and kinematics were quantified during the climbing task.

Main Results:

• The CFA selectively activates specific muscles while sparing or suppressing antagonists during climbing.
• Distinct linear components of CFA activity were identified that correlate with observed muscle activation patterns.
• These neural components differ significantly from those associated with muscle activity and kinematics.

Conclusions:

• The primary motor cortex exerts an instructive, selective influence on limb muscles during complex motor behaviors.
• This motor control relies on a specific subspace of neural activity within the CFA.
• The findings provide mechanistic insights into direct motor cortical control of the limbs.