Functional reorganization and stability of somatosensory-motor cortical topography in a tetraplegic subject with late recovery

PNAS, 2002 · DOI: 10.1073/pnas.262669099 · Published: December 24, 2002

Simple Explanation

This study used fMRI to examine the brain activity of a person with a spinal cord injury who regained some sensory and motor function after several years. Researchers looked at how the brain responded to touch and movement. The study found that the area of the brain that normally responds to hand stimulation did not respond in the injured person. Instead, this area responded to tongue movements. However, the area of the brain that responds to foot stimulation and the motor areas were mostly normal. These findings suggest the brain can reorganize after a spinal cord injury, and that some brain functions can be preserved even without movement or sensation.

Study Duration

8 Years

Participants

1 tetraplegic subject, 1 control subject

Evidence Level

Level 4, Case Study

Key Findings

1
Vibratory stimulation of the hand did not activate the primary somatosensory cortex (SI) hand area.
2
The SI hand area was recruited during tongue movements.
3
Vibratory stimulation of the foot evoked topographically appropriate responses in SI and second somatosensory cortex (SII).

Research Summary

The study investigated the functional organization of somatosensory and motor cortex in an individual with a high cervical spinal cord injury and late recovery of function. fMRI results showed reorganization in the SI hand area, which responded to tongue movements instead of hand stimulation. Motor cortex responses and somatosensory responses to foot stimulation displayed near-typical topography, suggesting preservation of some cortical representations.

Practical Implications

Rehabilitation Strategies

The findings suggest that rehabilitation therapies can be effective even years after a spinal cord injury, potentially by leveraging preserved neural pathways and promoting cortical reorganization.

Neural Repair Therapies

The preservation of motor and somatosensory cortical representations in the absence of overt movements or conscious sensations suggests that restoring spinal cord connections can re-establish motor and sensory functions.

Assessment of Neural Integrity

fMRI can be a valuable tool for assessing neural integrity across cord lesions, understanding the functional effects of SCI on the brain, and evaluating the effectiveness of novel therapies.

Study Limitations

1
The study is based on a single case, limiting the generalizability of the findings.
2
Longitudinal fMRI data is lacking, making it difficult to establish a causal relationship between brain activations, clinical recovery, and physical therapy.
3
The continuity of white-matter pathways across the lesion could not be definitively determined from the structural MRI images.

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