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Motor areas of the cerebral cortex
1Department of Neuroscience, Brown University, Providence, Rhode Island 02912.
Summary
The motor cortex, including the premotor area (PMA), supplementary motor area (SMA), and primary motor cortex (MI), plays a key role in voluntary movement and learning. Its representations rapidly reorganize based on experience or injury.
Area of Science:
- Neuroscience
- Motor Control
- Cortical Plasticity
Background:
- The motor cortex, a key component of the frontal agranular cortex, receives extensive inputs from sensory, motor, and modulatory pathways.
- It projects widely throughout the nervous system, influencing descending motor control pathways and spinal circuitry.
Purpose of the Study:
- To present new perspectives on the functional organization and plasticity of the motor cortex.
- To elucidate the distinct roles of the premotor area (PMA), supplementary motor area (SMA), and primary motor cortex (MI) in movement control.
Main Methods:
- Review and synthesis of existing research on motor cortex function.
- Analysis of data suggesting functional subdivisions within the primary motor cortex (MI).
- Examination of evidence for rapid reorganization of motor representations.
Main Results:
- The primary motor cortex (MI) exhibits functional subdivisions for face, arm, and leg with overlapping, interconnected, and non-topographic organization.
- Motor cortex representations demonstrate rapid reorganization in response to experience or peripheral lesions.
- Distinct roles are proposed: PMA for cue-motor act coupling, SMA for movement planning, and MI for higher-order parameters like movement direction.
Conclusions:
- The motor cortex, through its distinct areas and adaptable neural circuitry, is crucial for motor learning and the execution of voluntary movements.
- Understanding the plasticity of motor representations is key to comprehending motor skill acquisition and recovery from injury.