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Updated: Jul 19, 2026
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Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns
Published on: May 12, 2019
Visual evoked potentials modulation during direct current cortical polarization
Neri Accornero1, Pietro Li Voti, Maurizio La Riccia
1Department of Neurological Sciences, University of Rome La Sapienza, Viale Regina Elena 336, 00161 Rome, Italy. neri.accornero@uniroma1.it
Experimental Brain Research
|October 20, 2006
Summary
Transcranial direct current stimulation (tDCS) impacts visual cortex excitability. Anodal tDCS reduced visual evoked potential (VEP) amplitude, while cathodal tDCS increased it, with effects varying by stimulation duration.
Area of Science:
- Neuroscience
- Electrophysiology
- Visual System Research
Background:
- Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique.
- The precise effects of anodal versus cathodal tDCS on cortical excitability, particularly in the visual system, remain debated.
- Visual evoked potentials (VEPs) offer a measurable index of visual pathway function.
Purpose of the Study:
- To investigate the differential effects of anodal and cathodal tDCS on visual evoked potentials (VEPs) in healthy volunteers.
- To examine how tDCS duration (3 min vs. 10 min) influences VEP changes.
- To determine if tDCS-induced VEP alterations persist after stimulation cessation and their dependence on stimulus contrast.
Main Methods:
- Healthy volunteers received 1 mA tDCS targeting the occipital scalp with neck-base reference electrodes.
- VEP-P100 latency and amplitude were recorded before, during, and after tDCS.
- Stimulation involved both anodal and cathodal polarities and durations of 3 and 10 minutes.
- Pattern-reversal checkerboard stimuli were used, with varying contrast levels.
Main Results:
- Anodal tDCS significantly reduced VEP-P100 amplitude; cathodal tDCS significantly increased it.
- Neither anodal nor cathodal tDCS significantly altered VEP-P100 latency.
- Aftereffects on VEPs persisted post-tDCS, influenced by stimulation duration and stimulus contrast.
- Changes observed during stimulation were more consistent than aftereffects.
Conclusions:
- tDCS elicits polarity-specific modulations of visual cortical excitability, primarily affecting VEP amplitude.
- The duration of tDCS and visual stimulus characteristics modulate the observed VEP changes and their persistence.
- Investigating VEPs during tDCS provides a reliable window into the immediate effects of non-invasive brain stimulation on visual processing.
