The brain activation on upper extremity motor control tasks in different forces levels.

Area of Science:

• Neuroscience
• Motor Control Research
• Brain Imaging

Background:

• Motor control is essential for daily activities, involving nerve impulses from the motor cortex.
• Understanding brain activation during upper extremity tasks is crucial for rehabilitation and performance enhancement.

Purpose of the Study:

• To investigate brain activation patterns in the motor cortex during upper extremity force-regulating tasks.
• To differentiate neural responses to static versus dynamic movements and varying task difficulties.

Main Methods:

• Functional Near-Infrared Spectroscopy (fNIRS) was used to measure hemodynamic responses in healthy adults.
• Participants performed upper extremity motor control tasks using robotic arms, varying movement type (static/dynamic) and force difficulty.
• Hemodynamic signals were recorded from the primary motor cortex (M1), premotor cortex (PMC), supplementary motor area (SMA), and prefrontal cortex (PFC).

Main Results:

• A greater decrease in oxygenated hemoglobin (HbO) in the PFC was observed during static compared to dynamic movements.
• Increased HbO was found in the contralateral (c) M1, ipsilateral (i) PFC, and PMC with increasing task difficulty.
• Separate cortical circuits were identified for upper-extremity force and movement regulation.

Conclusions:

• Brain activation in cM1, PMC, and iPFC increases with task difficulty.
• The PFC plays a key role in distinguishing between static and dynamic upper extremity movements.
• Motor control of force and movement involves distinct neural pathways within the brain.