title: Motor imagery after subcortical stroke: a functional magnetic resonance imaging study.
abstract: OBJECTIVE
  In recovered subcortical stroke, the pattern of motor network activation during motor execution can appear normal or not, depending on the task. Whether this applies to other aspects of motor function is unknown. We used functional MRI to assess motor imagery (MI), a promising new approach to improve motor function after stroke, and contrasted it to motor execution.
  
  
  METHODS
  Twenty well-recovered patients with hemiparetic subcortical stroke (14 males; mean age, 66.5 years) and 17 aged-matched control subjects were studied. Extensive behavioral screening excluded 8 patients and 4 control subjects due to impaired MI abilities. Subjects performed MI and motor execution of a paced finger-thumb opposition sequence using a functional MRI paradigm that monitored compliance. Activation within the primary motor cortex (BA4a and 4p), dorsal premotor, and supplementary motor areas was examined.
  
  
  RESULTS
  The pattern of activation during affected-hand motor execution was not different from control subjects. Affected-hand MI activation was also largely similar to control subjects, including involvement of BA4, but with important differences: (1) unlike control subjects and the nonaffected hand, activation in BA4a and dorsal premotor was not lower during MI as compared with motor execution; (2) the hemispheric balance of BA4p activation was significantly less lateralized than control subjects; and (3) ipsilesional BA4p activation positively correlated with motor performance.
  
  
  CONCLUSIONS
  In well-recovered subcortical stroke, the motor system, including ipsilesional BA4, is activated during MI despite the lesion. It, however, remains disorganized in proportion to residual motor impairment. Thus, components of movement upstream from execution appear differentially affected after stroke and could be targeted by rehabilitation in more severely affected patients.
authors.affiliation: Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Sharma
authors.forename: Lucy H
authors.initials: LH
authors.lastname: Simmons
authors.forename: P Simon
authors.initials: PS
authors.lastname: Jones
authors.forename: Diana J
authors.initials: DJ
authors.lastname: Day
authors.forename: T Adrian
authors.initials: TA
authors.lastname: Carpenter
authors.forename: Valerie M
authors.initials: VM
authors.lastname: Pomeroy
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Warburton
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Baron
mesh_terms: D000368:Aged; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D010291:Paresis / Q000503:physiopathology / Q000534:rehabilitation; D020521:Stroke / Q000503:physiopathology*; D000071939:Stroke Rehabilitation; D013933:Thumb / Q000294:innervation / Q000502:physiology