title: Temporal profile of functional visual rehabilitative outcomes modulated by transcranial direct current stimulation.
abstract: OBJECTIVE
  We have previously reported that transcranial direct current stimulation (tDCS) delivered to the occipital cortex enhances visual functional recovery when combined with three months of computer-based rehabilitative training in patients with hemianopia. The principal objective of this study was to evaluate the temporal sequence of effects of tDCS on visual recovery as they appear over the course of training and across different indicators of visual function.
  
  
  METHODS
  Primary objective outcome measures were 1) shifts in visual field border and 2) stimulus detection accuracy within the affected hemifield. These were compared between patients randomized to either vision restoration therapy (VRT) combined with active tDCS or VRT paired with sham tDCS. Training comprised two half-hour sessions, three times a week for three months. Primary outcome measures were collected at baseline (pretest), monthly interim intervals, and at posttest (three months). As secondary outcome measures, contrast sensitivity and reading performance were collected at pretest and posttest time points only.
  
  
  RESULTS
  Active tDCS combined with VRT accelerated the recovery of stimulus detection as between-group differences appeared within the first month of training. In contrast, a shift in the visual field border was only evident at posttest (after three months of training). tDCS did not affect contrast sensitivity or reading performance.
  
  
  CONCLUSIONS
  These results suggest that tDCS may differentially affect the magnitude and sequence of visual recovery in a manner that is task specific to the type of visual rehabilitative training strategy employed.
authors.affiliation: The Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Ela B
authors.initials: EB
authors.lastname: Plow
authors.forename: Souzana N
authors.initials: SN
authors.lastname: Obretenova
authors.forename: Mary Lou
authors.initials: ML
authors.lastname: Jackson
authors.forename: Lotfi B
authors.initials: LB
authors.lastname: Merabet
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D015350:Contrast Sensitivity; D004311:Double-Blind Method; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D006423:Hemianopsia / Q000209:etiology / Q000503:physiopathology / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance / Q000502:physiology; D011932:Reading; D020127:Recovery of Function; D020521:Stroke / Q000150:complications; D016896:Treatment Outcome; D014785:Vision, Ocular / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology