title: Reflections on mirror therapy: a systematic review of the effect of mirror visual feedback on the brain.
abstract: BACKGROUND
  Mirror visual feedback (MVF), a phenomenon where movement of one limb is perceived as movement of the other limb, has the capacity to alleviate phantom limb pain or promote motor recovery of the upper limbs after stroke. The tool has received great interest from health professionals; however, a clear understanding of the mechanisms underlying the neural recovery owing to MVF is lacking.
  
  
  OBJECTIVE
  We performed a systematic review to assess the effect of MVF on brain activation during a motor task.
  
  
  METHODS
  We searched PubMed, CINAHL, and EMBASE databases for neuroimaging studies investigating the effect of MVF on the brain. Key details for each study regarding participants, imaging methods, and results were extracted.
  
  
  RESULTS
  The database search yielded 347 article, of which we identified 33 suitable for inclusion. Compared with a control condition, MVF increases neural activity in areas involved with allocation of attention and cognitive control (dorsolateral prefrontal cortex, posterior cingulate cortex, S1 and S2, precuneus). Apart from activation in the superior temporal gyrus and premotor cortex, there is little evidence that MVF activates the mirror neuron system. MVF increases the excitability of the ipsilateral primary motor cortex (M1) that projects to the "untrained" hand/arm. There is also evidence for ipsilateral projections from the contralateral M1 to the untrained/affected hand as a consequence of training with MVF.
  
  
  CONCLUSIONS
  MVF can exert a strong influence on the motor network, mainly through increased cognitive penetration in action control, though the variance in methodology and the lack of studies that shed light on the functional connectivity between areas still limit insight into the actual underlying mechanisms.
authors.affiliation: Ghent University, Ghent, Belgium Manchester Metropolitan University, Manchester, UK Frederik.Deconinck@UGent.be.
authors.forename: Frederik J A
authors.initials: FJ
authors.lastname: Deconinck
authors.affiliation: Burke-Cornell Medical Research Institute, White Plains, NY, USA.
authors.forename: Ana R P
authors.initials: AR
authors.lastname: Smorenburg
authors.affiliation: Bradford Institute for Health Research, Bradford, UK.
authors.forename: Alex
authors.initials: A
authors.lastname: Benham
authors.affiliation: VU University, Amsterdam, Netherlands.
authors.forename: Annick
authors.initials: A
authors.lastname: Ledebt
authors.affiliation: University of Birmingham, Birmingham, UK.
authors.forename: Max G
authors.initials: MG
authors.lastname: Feltham
authors.affiliation: VU University, Amsterdam, Netherlands.
authors.forename: Geert J P
authors.initials: GJ
authors.lastname: Savelsbergh
mesh_terms: D001921:Brain / Q000503:physiopathology*; D056228:Feedback, Sensory / Q000502:physiology*; D006801:Humans; D059167:Mirror Neurons / Q000502:physiology; D009473:Neuronal Plasticity; D026741:Physical Therapy Modalities; D020521:Stroke / Q000503:physiopathology*; D000071939:Stroke Rehabilitation
keywords: cerebral palsy; hemiparesis; mirror; sensorimotor control; stroke; systematic review; visual feedback