Supplementary motor area

Definition

The supplementary motor area (SMA) is a region of the brain located on the medial surface of the frontal lobe, involved in planning and coordinating complex movements. It plays a critical role in the execution of voluntary movements and is also important for motor imagery and the sequencing of movements, which are essential for tasks requiring intricate motor skills.

5 Must Know Facts For Your Next Test

1. The supplementary motor area is crucial for initiating bimanual coordination, which involves coordinating movements of both hands.
2. Activity in the SMA increases during tasks that require planning and executing sequences of movements rather than simple reflex actions.
3. Lesions in the SMA can lead to deficits in the ability to perform complex, learned motor tasks, highlighting its role in motor memory.
4. The SMA is also activated during mental rehearsal of movements, demonstrating its involvement in both physical execution and cognitive aspects of movement.
5. Research indicates that the SMA interacts with other areas, like the primary motor cortex and premotor cortex, to create a comprehensive network for movement control.

Review Questions

• How does the supplementary motor area contribute to the coordination of bimanual movements?
  • The supplementary motor area is essential for coordinating movements that involve both hands working together. It helps plan and execute complex sequences of actions, ensuring that both sides of the body move harmoniously. By integrating sensory information and past experiences related to movement, the SMA enables fluid and coordinated performance during tasks that require simultaneous use of both hands.
• Discuss how lesions in the supplementary motor area affect motor skills and learning.
  • Lesions in the supplementary motor area can significantly impair an individual's ability to perform complex learned motor tasks. This includes difficulties with executing planned sequences of movement, such as playing a musical instrument or performing athletic skills. Patients may exhibit problems with coordination and may rely more on reflexive actions rather than planned movements, showing how critical the SMA is for both motor execution and memory.
• Evaluate the role of the supplementary motor area in relation to cognitive aspects of movement preparation and execution.
  • The supplementary motor area not only plays a vital role in physically executing movements but also heavily influences cognitive processes related to movement preparation. It becomes active when individuals mentally rehearse or visualize performing tasks, indicating its importance beyond mere physical action. This dual function suggests that the SMA is integral to developing strategies for movement, planning actions based on environmental cues, and improving performance through practice and memory recall.

Related terms

premotor cortex: A part of the frontal lobe involved in the planning of movements and preparing the body for action, often in response to external cues.

primary motor cortex:

The area of the brain located in the precentral gyrus that directly controls voluntary muscle movements through its connections to spinal motor neurons.

basal ganglia: A group of nuclei in the brain that play a key role in coordinating movement and regulating motor control, working closely with the SMA and other motor areas.