Alterations in Motor Cortical Representation of Muscles Following Incomplete Spinal Cord Injury in Humans

Brain Sci., 2018 · DOI: 10.3390/brainsci8120225 · Published: December 16, 2018

Spinal Cord Injury Neurology Neuroplasticity

Simple Explanation

This study uses transcranial magnetic stimulation (TMS) to map brain activity in people with spinal cord injuries. TMS is a non-invasive way to stimulate the brain and see how it responds. The researchers looked at how the brain's motor cortex, which controls movement, is organized in individuals with spinal cord injuries compared to those without. They mapped the brain representations of specific arm and hand muscles. The study found that in people with spinal cord injuries, the brain area representing the hand muscle was larger, and the location of muscle representations was shifted compared to the control group. This suggests the brain reorganizes itself after a spinal cord injury.

Study Duration

Not specified

Participants

9 SCI participants and 9 age-, handed-, and sex-matched able-bodied controls

Evidence Level

Level 3, Case-control study

Key Findings

1
Muscle representations in SCI are shifted medially compared to controls.
2
SCI demonstrate a preserved general somatotopic arrangement, similar to uninjured controls.
3
Territory dedicated to the APB muscle is greater in SCI compared to controls.

Research Summary

The present study examined bilateral cortical organization in individuals with chronic incomplete cervical SCI and uninjured controls. Several novel ﬁndings were revealed that provide new information regarding the reorganizational changes that manifest in M1 following SCI. Our results are in line with these ﬁndings as cortical territory of APB, a muscle impaired in every participant, was enlarged compared to controls, while the territories of FCR and BB, muscles that likely retained a larger proportion of innervation (Table 1, see injury levels), did not differ in size from controls (Figure 4B). We report deviations in the M1 representation in individuals with SCI compared to uninjured controls that include a medial shift in representations and expansion of a hand muscle.

Practical Implications

Understanding Functional Deficits

The altered organization of the motor cortex in SCI may help explain the functional deficits observed in these individuals.

Improving Rehabilitation Techniques

The findings can inform rehabilitation techniques aimed at restoring function after SCI by targeting specific areas of cortical reorganization.

Predicting and Monitoring Recovery

Quantifying motor cortex map characteristics in SCI may be useful for predicting and monitoring functional recovery.

Study Limitations

1
Responses to TMS may be due to activation in surrounding associated motor regions, particularly at the edges of the grid space.
2
A relatively small sample size limited by participant availability.
3
It remains unclear how these conditions and their pharmacological treatment may contribute to cortical reorganization following injury.

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