Article

Failure of adaptive plasticity with increasing pathology is suggested
to contribute to progression of disability in multiple sclerosis (MS). However,
functional impairments can be reduced with practice, suggesting that brain
plasticity is preserved even in patients with substantial damage. OBJECTIVE: .
Here, functional magnetic resonance imaging (fMRI) was used to probe
systems-level mechanisms of brain plasticity associated with improvements in
visuomotor performance in MS patients and related to measures of microstructural
damage. METHODS: 23 MS patients and 12 healthy controls underwent brain fMRI
during the first practice session of a visuomotor task (short-term practice) and
after 2 weeks of daily practice with the same task (longer-term practice).
Participants also underwent a structural brain MRI scan. RESULTS: Patients
performed more poorly than controls at baseline. Nonetheless, with practice,
patients showed performance improvements similar to controls and independent of
the extent of MRI measures of brain pathology. Different relationships between
performance improvements and activations were found between groups: greater
short-term improvements were associated with lower activation in the
sensorimotor, posterior cingulate, and parahippocampal cortices for patients,
whereas greater long-term improvements correlated with smaller activation
reductions in the visual cortex of controls. CONCLUSIONS: Brain plasticity for
visuomotor practice is preserved in MS patients despite a high burden of cerebral
pathology. Cognitive systems different from those acting in controls contribute
to this plasticity in patients. These findings challenge the notion that
increasing pathology is accompanied by an outright failure of adaptive
plasticity, supporting a neuroscientific rationale for recovery-oriented
strategies even in chronically disabled patients.

Langue : ANGLAIS