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Transcranial Direct Current Stimulation and Simultaneous Functional Magnetic Resonance Imaging
Published on: April 27, 2014
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No Modulation of Visual Cortex Excitability by Transcranial Direct Current Stimulation
Sabrina Brückner1, Thomas Kammer1
1Section for Neurostimulation, Department of Psychiatry, University of Ulm, Ulm, Germany.
Plos One
|December 10, 2016
Summary
Transcranial direct current stimulation (tDCS) did not modulate visual cortex excitability, contrary to prior studies. High individual variability and low reliability were observed, questioning tDCS effectiveness for visual cortex modulation.
Area of Science:
- Neuroscience
- Cognitive Science
- Psychophysics
Background:
- Phosphene thresholds (PTs) measure visual cortex excitability.
- Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are used to modulate this excitability.
- Previous research suggests neural state influences stimulation effects.
Purpose of the Study:
- To investigate if visual cortex activity after tDCS influences its modulatory effects.
- To assess the impact of varying visual demand on tDCS-induced changes in excitability.
Main Methods:
- A between-group design was employed.
- Anodal or cathodal tDCS was applied to the visual cortex.
- Participants underwent high or low visual demand tasks post-stimulation.
Main Results:
- No modulation of PTs was observed directly after tDCS or visual demand tasks.
- High inter-individual variability in tDCS response was noted.
- Intra-individual reliability in modulation direction was found only for cathodal tDCS.
Conclusions:
- The study did not confirm previously reported modulatory effects of tDCS on visual cortex excitability.
- Results suggest limited reliability of tDCS effects across different measurement outcomes.
- High inter-individual variability may obscure consistent tDCS-induced modulations.
