Long-Term Effects of Serial Anodal tDCS on Motion Perception in Subjects with Occipital Stroke Measured in the Unaffected Visual Hemifield

• Published in: Frontiers in human neuroscience Vol. 7; p. 314
• Main Authors: Olma, M. C., Dargie, R. A., Behrens, J. R., Kraft, A., Irlbacher, K., Fahle, M., Brandt, S. A.
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Research Foundation 24.06.2013; Frontiers Media S.A
• Subjects: Adaptation; Animal cognition; Automation; Blindness; Clinical trials; Electrical stimulation of the brain; ESB; Learning; Lesions; Long-term effects; Magnetic resonance imaging; Motion detection; Motion Perception; motor system; Motor systems; neuroplasticity; Neuroscience; Neurosciences; Population studies; Receptive field; Sensorimotor integration; Stroke; Studies; transcranial direct current stimulation; Transcranial magnetic stimulation; Visual cortex; Visual perception; Visual System; Germany; motor system; visual system; motion perception; learning; translational research; transcranial direct current stimulation; neuroplasticity
• ISSN: 1662-5161; 1662-5161
• DOI: 10.3389/fnhum.2013.00314

Transcranial direct current stimulation (tDCS) is a novel neuromodulatory tool that has seen early transition to clinical trials, although the high variability of these findings necessitates further studies in clinically relevant populations. The majority of evidence into effects of repeated tDCS is based on research in the human motor system, but it is unclear whether the long-term effects of serial tDCS are motor-specific or transferable to other brain areas. This study aimed to examine whether serial anodal tDCS over the visual cortex can exogenously induce long-term neuroplastic changes in the visual cortex. However, when the visual cortex is affected by a cortical lesion, up-regulated endogenous neuroplastic adaptation processes may alter the susceptibility to tDCS. To this end, motion perception was investigated in the unaffected hemifield of subjects with unilateral visual cortex lesions. Twelve subjects with occipital ischemic lesions participated in a within-subject, sham-controlled, double-blind study. MRI-registered sham or anodal tDCS (1.5 mA, 20 min) was applied on five consecutive days over the visual cortex. Motion perception was tested before and after stimulation sessions and at 14- and 28-day follow-up. After a 16-day interval an identical study block with the other stimulation condition (anodal or sham tDCS) followed. Serial anodal tDCS over the visual cortex resulted in an improvement in motion perception, a function attributed to MT/V5. This effect was still measurable at 14- and 28-day follow-up measurements. Thus, this may represent evidence for long-term tDCS-induced plasticity and has implications for the design of studies examining the time course of tDCS effects in both the visual and motor systems.