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Transcranial Direct Current Stimulation tDCS for Memory Enhancement
Published on: September 18, 2021
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No effects of anodal transcranial direct current stimulation on contrast sensitivity function
Qing He1,2, Bo-Rong Lin1,2, Jin Zhao1,2
1Key Laboratory of Behavioral Sciences, Institute of Psychology, Chinese Academy of Sciences, Beijing, China.
Restorative Neurology and Neuroscience
|March 12, 2019
Summary
Anodal transcranial direct current stimulation (tDCS) did not significantly alter contrast sensitivity functions (CSF) in healthy adults over two sessions. Individual responsiveness and measurement precision did not explain the lack of effect, suggesting tDCS may not be effective for visual modulation.
Area of Science:
- Neuroscience
- Visual Science
- Brain Stimulation
Background:
- Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique used to modulate cortical excitability.
- Previous studies on tDCS effects on contrast sensitivity functions (CSF), a fundamental visual function, have yielded mixed results.
Purpose of the Study:
- To systematically investigate the effects of anodal tDCS on CSF.
- To evaluate the role of individual responsiveness in tDCS effects on CSF.
- To assess the impact of measurement precision on observed tDCS outcomes.
Main Methods:
- A single-blinded, sham-controlled, within-subject study design was employed.
- Twenty-seven healthy adults received three sessions of tDCS (two anodal, one sham) over the Oz region, with CSF measured pre- and post-stimulation.
- CSF was assessed using a precise Bayesian procedure; responsiveness and precision were quantified.
Main Results:
- Neither the first nor the second anodal tDCS session significantly altered CSF.
- Responsiveness to tDCS varied inconsistently between sessions, challenging the responder/non-responder explanation.
- Measurement precision was high (less than 2 dB) and consistent throughout the experiment.
Conclusions:
- Anodal tDCS, at least with two sessions, demonstrated no significant effect on modulating CSF.
- The lack of effect was not attributable to individual subject responsiveness or limitations in measurement precision.
- Further research is required to identify optimal configurations for tDCS-induced visual modulation.
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