Correlations Between Primary Motor Cortex Activity with Recent Past and Future Limb Motion During Unperturbed...

Area of Science:

• Neuroscience
• Motor Control
• Primate Behavior

Background:

• Human movements show trial-to-trial variability, with initial errors corrected by movement's end.
• This suggests an online control process, but its role in addressing internal motor noise is unclear.

Purpose of the Study:

• To investigate trial-by-trial variability in goal-directed reaching in Rhesus monkeys.
• To determine the relationship between primary motor cortex (M1) neural variability and hand motion variability during reaching.

Main Methods:

• Analysis of reaching movements in nonhuman primates (Rhesus monkeys).
• Correlation analysis of trial-by-trial neural variability in M1 with past and future hand motion variability.
• Partial correlation to assess independent contributions of M1 activity.

Main Results:

• Rhesus monkeys exhibit similar reaching variability patterns as humans, including negative correlation between initial and late hand motion.
• M1 neural variability positively correlates with future hand motion variability (τ ≈ 160 ms).
• M1 neural variability negatively correlates with past hand motion variability (τ ≈ 90 ms), independently reflecting both.

Conclusions:

• M1 activity is linked to online feedback motor control.
• Findings support the hypothesis that M1 addresses internal noise and errors within the motor system during reaching.