Effect of force accuracy on hemodynamic response: an fNIRS study using fine visuomotor task

Area of Science:

• Neuroscience
• Motor Control
• Human Physiology

Background:

• Neuroimaging studies often examine movement velocity and force magnitude.
• The impact of force accuracy on neural responses remains under-investigated.
• Understanding task difficulty's neural basis is crucial for motor control research.

Purpose of the Study:

• To investigate the effect of varying force accuracy demands on cortical neural responses.
• To explore how task difficulty influences brain activation and connectivity during a visuomotor task.
• To identify the relationship between force accuracy and hemodynamic signals.

Main Methods:

• Functional near-infrared spectroscopy (fNIRS) recorded brain activity in healthy adults.
• Participants performed a visuomotor task with six levels of force accuracy.
• Hemoglobin concentration changes indicated cortical activation; Granger causality assessed effective connectivity.

Main Results:

• Higher force accuracy initially increased oxy-hemoglobin concentration and effective connectivity.
• Excessive force accuracy demands led to decreased activation and connectivity.
• These findings suggest an inverted U-shaped relationship between task difficulty and neural response.

Conclusions:

• Force accuracy exhibits an inverted U-shaped effect on hemodynamic responses in fine visuomotor tasks.
• Inter-region connectivity alterations are key to coping with task difficulty.
• This research enhances understanding of motor neural processes and informs neurorehabilitation strategies.