Excitability changes induced in the human primary visual cortex by transcranial direct current stimulation: direct electrophysiological evidence.

@article{citeulike:3128978, abstract = {PURPOSE: Transcranial direct current stimulation (tDCS) has been shown to modify the perception threshold of phosphenes elicited by transcranial magnetic stimulation (TMS). The current study was undertaken to examine whether tDCS, when applied over the occipital cortex, is also able to affect visual-evoked potentials (VEPs), which characterize occipital activation in response to visual stimulation, in a polarity-specific way. METHOD: For this purpose, VEPs evoked by sinusoidal luminance grating in an on/off mode were recorded before, immediately after, and 10, 20, and 30 minutes after the end of 5, 10, or 15 minutes of anodal or cathodal tDCS of the primary visual cortex. RESULTS: Significant effects were observed only when low-contrast visual stimuli were applied. Cathodal stimulation decreased, whereas anodal stimulation increased the amplitude of the N70 component. The effect of cathodal stimulation was significant immediately after and 10 minutes after the end of stimulation, if the stimulation duration was sufficiently long (i.e., 10-15 minutes). An increase of N70 amplitude by anodal stimulation was significant only 10 minutes after the end of the 15 minutes tDCS. Cathodal stimulation tended also to affect the amplitude of the P100 component; however, the effect of stimulation was inverse. The amplitude increased immediately after the end of cathodal stimulation. In contrast, anodal stimulation did not affect the P100. The latencies of the N70 and the P100 were not affected by tDCS. CONCLUSIONS: tDCS appears to be a suitable method of inducing reversible excitability changes in a polarity-specific way, not only in the motor but also in the primary visual cortex. The duration of the induced aftereffects depends not only on stimulation duration but also on stimulation polarity. Cathodal stimulation seems to be more effective, in line with previous reports on the motor cortex.}, address = {Department of Clinical Neurophysiology, Georg-August University, G\"{o}ttingen, Germany. aantal@gwdg.de}, author = {Antal, A. and Kincses, T. Z. and Nitsche, M. A. and Bartfai, O. and Paulus, W. }, citeulike-article-id = {3128978}, comment = {* Measured visual evoked potentials in response to sinusoidal gratings (particularly low-contrast ones) in response to tDCS * Cathodal stimulation decreased amplitude of N70, anodal stimulation increased * cathodal stimulation increased amplitude of P100, no anodal effect * latencies of N70 and P100 remained the same}, issn = {0146-0404}, journal = {Investigative ophthalmology \& visual science}, keywords = {tdcs, tdcs-eeg, tdcs-visual-cortex, visual-evoked-potential}, month = {February}, number = {2}, pages = {702--707}, posted-at = {2008-08-16 21:17:20}, priority = {2}, title = {Excitability changes induced in the human primary visual cortex by transcranial direct current stimulation: direct electrophysiological evidence.}, url = {http://view.ncbi.nlm.nih.gov/pubmed/14744917}, volume = {45}, year = {2004} }

TY - JOUR ID - citeulike:3128978 L3 - citeulike-article-id:3128978 N2 - PURPOSE: Transcranial direct current stimulation (tDCS) has been shown to modify the perception threshold of phosphenes elicited by transcranial magnetic stimulation (TMS). The current study was undertaken to examine whether tDCS, when applied over the occipital cortex, is also able to affect visual-evoked potentials (VEPs), which characterize occipital activation in response to visual stimulation, in a polarity-specific way. METHOD: For this purpose, VEPs evoked by sinusoidal luminance grating in an on/off mode were recorded before, immediately after, and 10, 20, and 30 minutes after the end of 5, 10, or 15 minutes of anodal or cathodal tDCS of the primary visual cortex. RESULTS: Significant effects were observed only when low-contrast visual stimuli were applied. Cathodal stimulation decreased, whereas anodal stimulation increased the amplitude of the N70 component. The effect of cathodal stimulation was significant immediately after and 10 minutes after the end of stimulation, if the stimulation duration was sufficiently long (i.e., 10-15 minutes). An increase of N70 amplitude by anodal stimulation was significant only 10 minutes after the end of the 15 minutes tDCS. Cathodal stimulation tended also to affect the amplitude of the P100 component; however, the effect of stimulation was inverse. The amplitude increased immediately after the end of cathodal stimulation. In contrast, anodal stimulation did not affect the P100. The latencies of the N70 and the P100 were not affected by tDCS. CONCLUSIONS: tDCS appears to be a suitable method of inducing reversible excitability changes in a polarity-specific way, not only in the motor but also in the primary visual cortex. The duration of the induced aftereffects depends not only on stimulation duration but also on stimulation polarity. Cathodal stimulation seems to be more effective, in line with previous reports on the motor cortex. IS - 2 JF - Investigative ophthalmology & visual science SN - 0146-0404 AD - Department of Clinical Neurophysiology, Georg-August University, Göttingen, Germany. aantal@gwdg.de EP - 707 TI - Excitability changes induced in the human primary visual cortex by transcranial direct current stimulation: direct electrophysiological evidence. VL - 45 SP - 702 KW - tdcs KW - tdcs-eeg KW - tdcs-visual-cortex KW - visual-evoked-potential N1 - * Measured visual evoked potentials in response to sinusoidal gratings (particularly low-contrast ones) in response to tDCS * Cathodal stimulation decreased amplitude of N70, anodal stimulation increased * cathodal stimulation increased amplitude of P100, no anodal effect * latencies of N70 and P100 remained the same AU - Antal, A AU - Kincses, TZ AU - Nitsche, MA AU - Bartfai, O AU - Paulus, W PY - 2004/02// UR - http://view.ncbi.nlm.nih.gov/pubmed/14744917 ER -