Selective Long-term Reorganization of the Corticospinal Projection from the Supplementary Motor Cortex following Recovery from Lateral Motor Cortex Injury

J Comp Neurol, 2010 · DOI: 10.1002/cne.22218 · Published: March 1, 2010

Simple Explanation

This research investigates how the brain recovers after injury to the motor cortex, specifically focusing on the role of the supplementary motor cortex (M2). The study found that after damage to the primary motor cortex (M1), M2 reorganizes its connections to the spinal cord. This reorganization, called plasticity, involves the growth of new connections in specific areas of the spinal cord related to hand and finger movement. Subsequent damage to M2 after recovery, leads to the reemergence of motor deficits. These findings suggest that M2 plays a crucial role in regaining motor function after brain injury and could be a target for therapies aimed at improving motor recovery. It is observed that the areas of the spinal cord, that receive the enhanced projections from M2, are critical for recovery of motor function.

Study Duration

6-12 Months

Participants

8 rhesus monkeys

Evidence Level

Not specified

Key Findings

1
Recovery of dexterous movements from isolated lateral frontal injury is accompanied by selective contralateral terminal axon sprouting and bouton proliferation that is restricted to spinal laminae VII and IX.
2
Following recovery, subsequent injury to M2 leads to rapid reemergence of fine hand motor deficits but not paresis.
3
Significant contralateral plasticity occurs only in lamina VII and dorsally within lamina IX.

Research Summary

The study investigates the long-term effects of lateral frontal motor cortical injury on the corticospinal projection (CSP) from the supplementary motor cortex (M2). It demonstrates that recovery from injury to the primary motor cortex (M1) and lateral premotor cortex (LPMC) is accompanied by terminal axon plasticity in the contralateral CSP from M2. Significant contralateral plasticity occurs only in lamina VII and dorsally within lamina IX, regions containing interneurons, flexor-related motor neurons, and motor neurons supplying intrinsic hand muscles. Subsequent injury of M2 leads to reemergence of hand motor deficits. The findings suggest that spared supplementary motor cortex may serve as an important therapeutic target for enhancing motor recovery following lateral cortical trauma.

Practical Implications

Therapeutic Target

Spared supplementary motor cortex (M2) may serve as a crucial therapeutic target for enhancing motor recovery after lateral cortical trauma.

Rehabilitation Strategies

Acute and long-term post-injury patient intervention strategies should consider the role of M2 in enhancing motor recovery.

Clinical Relevance

Protect M2 in the acute phase following brain injury and evaluate its integrity, then recruit it in rehabilitation.

Study Limitations

1
Technical challenges in interpreting the precise location of the effective injection site.
2
Potential for retrograde transport of the tracer to influence results.
3
The study focuses primarily on the M2 corticospinal projection, while other contributing projection systems from M2 (corticocortical, corticorubral, corticopontine, and corticoreticular) likely play a role in recovery.

Your Feedback

Was this summary helpful?

Back to Neurology