title: Disruption of motor network connectivity post-stroke and its noninvasive neuromodulation.
abstract: OBJECTIVE
  We review the latest evidence for the neural underpinnings of hand motor function recovery after stroke with particular emphasis on how the latter can be enhanced by noninvasive brain stimulation techniques such as repetitive transcranial magnetic stimulation (rTMS) or transcranial direct current stimulation (tDCS).
  
  
  RESULTS
  New data from longitudinal studies in which rTMS of the lesioned or contralesional motor cortex was combined with motor training showed ambiguous effects: some patients improved whereas others did not show any rTMS effect (compared with control stimulation). In contrast, novel studies using tDCS point to a more consistent effect on distal upper limb function, especially for inhibitory (cathodal) tDCS applied over contralesional M1. Neuroimaging data reveal that the effects of rTMS/tDCS on the functional architecture of the motor system depend upon lesion location, degree of impairment and number of treatment sessions. Furthermore, analyses of regional brain activity and motor network connectivity allow prediction of the behavioural effects of brain stimulation.
  
  
  CONCLUSIONS
  rTMS and tDCS can be used to modulate stroke-induced changes of motor network activity and connectivity thereby improving hand motor function. The interindividual variability in response to brain stimulation calls for the identification of treatment-associated surrogate markers, which may be provided by neuroimaging.
authors.affiliation: Department of Neurology, University Hospital Cologne, Germany. Christian.Grefkes@uk-koeln.de
authors.forename: Christian
authors.initials: C
authors.lastname: Grefkes
authors.forename: Gereon R
authors.initials: GR
authors.lastname: Fink
mesh_terms: D004599:Electric Stimulation Therapy; D007839:Functional Laterality; D059907:Functional Neuroimaging; D006225:Hand / Q000294:innervation / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009044:Motor Cortex / Q000503:physiopathology*; D049268:Positron-Emission Tomography; D020127:Recovery of Function; D020521:Stroke / Q000503:physiopathology* / Q000628:therapy; D050781:Transcranial Magnetic Stimulation