title: Plasticity and response to action observation: a longitudinal FMRI study of potential mirror neurons in patients with subacute stroke.
abstract: BACKGROUND
  Action observation has been suggested as a possible gateway to retraining arm motor function post stroke. However, it is unclear if the neuronal response to action observation is affected by stroke and if it changes during the course of recovery.
  
  
  OBJECTIVE
  To examine longitudinal changes in neuronal activity in a group of patients with subacute stroke when observing and executing a bimanual movement task.
  
  
  METHODS
  Eighteen patients were examined twice using 3-T functional magnetic resonance imaging; 1 to 2 weeks and 3 months post stroke symptom onset. Eighteen control participants were examined once. Image time series were analyzed (SPM8) and correlated with clinical motor function scores.
  
  
  RESULTS
  During action observation and execution, an overlap of neuronal activation was observed in the superior and inferior parietal lobe, precentral gyrus, insula, and inferior temporal gyrus in both control participants and patients (P < .05; false discovery rate corrected). The neuronal response in the observation task increased from 1 to 2 weeks to 3 months after stroke. Most activated clusters were observed in the inferior temporal gyrus, the thalamus and movement-related areas, such as the premotor, supplementary and motor cortex (BA4, BA6). Increased activation of cerebellum and premotor area correlated with improved arm motor function. Most patients had regained full movement ability.
  
  
  CONCLUSIONS
  Plastic changes in neurons responding to action observation and action execution occurred in accordance with clinical recovery. The involvement of motor areas when observing actions early and later after stroke may constitute a possible access to the motor system.
authors.affiliation: University of Bergen, Bergen, Norway iris.brunner@igs.uib.no.
authors.forename: Iris C
authors.initials: IC
authors.lastname: Brunner
authors.affiliation: University of Bergen, Bergen, Norway.
authors.forename: Jan Sture
authors.initials: JS
authors.lastname: Skouen
authors.affiliation: Haukeland University Hospital, Bergen, Norway.
authors.forename: Lars
authors.initials: L
authors.lastname: Ersland
authors.affiliation: University of Bergen, Bergen, Norway Haukeland University Hospital, Bergen, Norway.
authors.forename: Renate
authors.initials: R
authors.lastname: Grüner
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D059167:Mirror Neurons / Q000473:pathology*; D009044:Motor Cortex / Q000098:blood supply / Q000473:pathology*; D019370:Observation; D010100:Oxygen / Q000097:blood; D020521:Stroke / Q000473:pathology*; D000071939:Stroke Rehabilitation
chemical_list: D010100:Oxygen
keywords: action observation; arm motor function; fMRI; mirror neurons; rehabilitation; stroke