Motor imagery: a backdoor to the motor system after stroke?
OBJECTIVE
Understanding brain plasticity after stroke is important in developing rehabilitation strategies. Active movement therapies show considerable promise but depend on motor performance, excluding many otherwise eligible patients. Motor imagery is widely used in sport to improve performance, which raises the possibility of applying it both as a rehabilitation method and to access the motor network independently of recovery. Specifically, whether the primary motor cortex (M1), considered a prime target of poststroke rehabilitation, is involved in motor imagery is unresolved.


RESULTS
We review methodological considerations when applying motor imagery to healthy subjects and in patients with stroke, which may disrupt the motor imagery network. We then review firstly the motor imagery training literature focusing on upper-limb recovery, and secondly the functional imaging literature in healthy subjects and in patients with stroke.


CONCLUSIONS
The review highlights the difficulty in addressing cognitive screening and compliance in motor imagery studies, particularly with regards to patients with stroke. Despite this, the literature suggests the encouraging effect of motor imagery training on motor recovery after stroke. Based on the available literature in healthy volunteers, robust activation of the nonprimary motor structures, but only weak and inconsistent activation of M1, occurs during motor imagery. In patients with stroke, the cortical activation patterns are essentially unexplored as is the underlying mechanism of motor imagery training. Provided appropriate methodology is implemented, motor imagery may provide a valuable tool to access the motor network and improve outcome after stroke.
Sharma
Nikhil
N
Department of Clinical Neurosciences, University of Cambridge, England.
Pomeroy
Valerie M
VM
Baron
Jean-Claude
JC
D000328:Adult; D004576:Electromyography; D005260:Female; D006225:Hand / Q000503:physiopathology; D018737:Hand Strength; D006801:Humans; D019018:Imagery, Psychotherapy; D008279:Magnetic Resonance Imaging; D008297:Male; D009043:Motor Activity; D009044:Motor Cortex / Q000503:physiopathology*; D009068:Movement; D009473:Neuronal Plasticity / Q000502:physiology*; D010243:Paralysis / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology / Q000534:rehabilitation; D049268:Positron-Emission Tomography; D011597:Psychomotor Performance / Q000502:physiology*; D012107:Research Design; D020521:Stroke / Q000150:complications / Q000503:physiopathology / Q000523:psychology; D000071939:Stroke Rehabilitation; D011795:Surveys and Questionnaires; D016896:Treatment Outcome