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Motor imagery after stroke: Relating outcome to motor network connectivity
Author(s) -
Sharma Nikhil,
Baron JeanClaude,
Rowe James B.
Publication year - 2009
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.21810
Subject(s) - neuroplasticity , neuroscience , psychology , premotor cortex , stroke (engine) , physical medicine and rehabilitation , motor imagery , supplementary motor area , functional magnetic resonance imaging , motor cortex , rehabilitation , prefrontal cortex , supramarginal gyrus , neurorehabilitation , medicine , electroencephalography , cognition , brain–computer interface , mechanical engineering , dorsum , stimulation , engineering , anatomy
Objective Neuroplasticity is essential for recovery after stroke and is the target for new stroke therapies. During recovery from subcortical motor stroke, brain activations associated with movement may appear normal despite residual functional impairment. This raises an important question: how far does recovery of motor performance depend on the processes that precede movement execution involving the premotor and prefrontal cortex, rather than recovery of the corticospinal system alone? Methods We examined stroke patients with functional magnetic resonance imaging while they either imagined or executed a finger‐thumb opposition sequence. In addition to classical analyses of regional activations, we studied neuroplasticity in terms of differential network connectivity using structural equation modeling. The study included 8 right‐handed patients who had suffered a left‐hemisphere subcortical ischemic stroke with paresis, and 13 age‐matched healthy controls. Results With good functional recovery, the regional activations had returned to normal in patients. However, connectivity within the extended motor network remained abnormal. These abnormalities were seen predominantly during motor imagery and correlated with motor performance. Interpretation Our results indicate that neuroplasticity can manifest itself as differences in connectivity among cortical areas remote from the infarct, rather than in the degree of regional activation. Connection strengths between nodes of the cortical motor network correlate with motor outcome. The altered organization of connectivity of the prefrontal areas may reflect the role of the prefrontal cortex in higher order planning of movement. Our results are relevant to the assessment and understanding of emerging physical and neurophysiological therapies for stroke rehabilitation. Ann Neurol 2009;66:604–616