fMRI effects of task demand and feedback accuracy on grip force tracking

Area of Science:

• Neuroscience
• Motor Control
• Human Performance

Background:

• Force control in visually guided tasks is sensitive to feedback accuracy and force-varying rate.
• Previous studies indicate that higher feedback accuracy and greater force-varying rates impair task performance.

Purpose of the Study:

• To investigate the neural mechanisms underlying performance decrements in visually guided force control.
• To examine the relationship between task difficulty, brain activation, and performance using functional magnetic resonance imaging (fMRI).

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to measure brain activity.
• Participants performed a visually guided continuous tracking task with varying feedback accuracy and force-varying rates.
• The blood-oxygen-level-dependent (BOLD) response was analyzed to assess neural activity in the visuomotor network.

Main Results:

• Task performance decreased with higher feedback accuracy and greater force-varying rates.
• fMRI data revealed increased BOLD signal in the visuomotor network during the task.
• Poorer performance conditions consistently showed higher activation levels in the visuomotor network, indicating parametric modulation by task difficulty.

Conclusions:

• Performance costs in visually guided force control are associated with increased neural demand within the visuomotor network.
• The findings suggest an interdependent and parallel neural control system for visual feedback and force output rate.
• This control is likely mediated by a shared neural network, adapting to task difficulty and force production demands.