Differential fronto-parietal activation depending on force used in a precision grip task: an fMRI study

Area of Science:

• Neuroscience
• Motor Control
• Human Brain Imaging

Background:

• Functional magnetic resonance imaging (fMRI) studies indicate bilateral frontal and parietal regions, along with the contralateral primary motor cortex, are vital for precision grips.
• The precise role of these brain areas in relation to varying grip force magnitudes remains an area for investigation.

Purpose of the Study:

• To investigate if specific brain regions associated with precision grips are more active during low-force exertions compared to high-force exertions.
• To examine the neural underpinnings of fine motor control in precision grip tasks.

Main Methods:

• Utilized fMRI to compare brain activity during precision grip tasks involving small (3.8 N) versus large (16.6 N) forces.
• Subjects performed isometric precision grips under controlled auditory and tactile guidance, generating both static and dynamic forces.

Main Results:

• Significantly stronger activation was observed in the bilateral ventral premotor cortex (area 44), rostral cingulate motor area, and right intraparietal cortex when applying small forces.
• These findings highlight differential engagement of secondary sensorimotor areas based on grip force magnitude.

Conclusions:

• Secondary sensorimotor areas in the frontal and parietal lobes play a critical role in the fine control of precision grip forces, particularly within the range used for everyday manipulation of small objects.
• The brain's recruitment of these areas is modulated by the required grip force, emphasizing their importance in delicate motor tasks.