Functional somatotopy revealed across multiple cortical regions using a model of complex motor task
David A Cunningham1, Andre Machado, Guang H Yue
1Department of Biomedical Engineering, Cleveland Clinic Foundation, USA.
Brain Research
|August 8, 2013
Summary
The primary motor cortex (M1) and supplementary motor area (SMA) integrate movements, while somatosensory (S1) and premotor cortices (PMC) specialize. This motor control hierarchy offers stroke rehabilitation opportunities.
Area of Science:
- Neuroscience
- Motor Control
- Brain Imaging
Background:
- The primary motor cortex (M1) has a somatotopic organization where adjacent joint representations overlap for coordination but maintain distinct centers for individual movements.
- It remains unclear if other sensorimotor cortices share this functional organization.
Purpose of the Study:
- To investigate the somatotopic organization across sensorimotor cortices (S1, PMC, M1, SMA, SPL, IPL) during complex movements.
- To determine the degree of overlap and distinctness of joint representations within and between limbs across these regions.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used on 24 healthy subjects performing complex finger, elbow, and ankle movements.
- Activation patterns were analyzed to identify representations for each joint, their centers of mass (COM), and the overlap between within-limb and between-limb joint representations.
Main Results:
- Somatosensory (S1) and premotor cortices (PMC) showed distinct centers of mass and minimal overlap, suggesting specialization.
- Primary motor cortex (M1) and supplementary motor area (SMA) exhibited more integrated somatotopy with significant overlap for within-limb representations.
- Parietal lobules (SPL and IPL) displayed mixed organization, with some areas showing extensive overlap and others distinct centers.
Conclusions:
- Sensorimotor cortices exhibit a hierarchical organization, with S1 potentially supporting individuated movements and M1 supporting coordinated motion.
- Parietal regions may act as associative areas, enabling switching between individuated and coordinated control modes.
- This hierarchical structure provides diverse avenues for stroke rehabilitation, utilizing complex movements to understand skill and plasticity.
Keywords:
Functional MRI or fMRIMotor controlMotor mapMovementPosterior parietal cortexPrimary motor cortex or M1RepresentationSomatotopyMore Related Videos
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