Neural Noise

tDCS and GABA or functional connectivity in visual cortex

2 min read

  • Anodal transcranial direct current stimulation does not alter GABA concentration or functional connectivity in the normal visual cortex (Frontiers).1
  • The null result informs expectations for neuromodulation and connectivity interpretation.1 1

Gardner updates

  • Anodal tDCS did not alter GABA concentration or functional connectivity in the normal visual cortex in a Frontiers study, informing expectations for neuromodulation and connectivity. 1

Weekly enrichment (2026-07-20)

  • The primary study (Frontiers in Neuroscience, 2025) tested whether anodal transcranial direct current stimulation (a-tDCS) of the healthy primary visual cortex alters local GABA concentration, the same paradigm that reduces GABA when applied to the motor cortex.23
  • Using magnetic resonance spectroscopy (MRS), the authors found no between-session effects of a-tDCS on GABA or Glx concentration, and no effect on visual cortex resting-state functional connectivity.23
  • A pre-planned within-session analysis showed a significant increase in Glx following a-tDCS, but this did not survive correction for multiple comparisons.23
  • The study also attempted to replicate a reported association between visual cortex GABA concentration and binocular rivalry dynamics, but found no consistent relationship.2
  • The authors conclude that visual cortex a-tDCS may act through a different mechanism than motor cortex a-tDCS, consistent with other reports that the two regions are differentially affected by stimulation.23
  • Motivation for the work is clinical: a-tDCS of the visual cortex is being explored as a rehabilitation tool for vision disorders such as amblyopia and macular degeneration, but its underlying neural mechanisms remain unknown.2
  • The null connectivity finding contrasts with reports of increased functional connectivity after motor cortex a-tDCS, underscoring caution when extrapolating neuromodulation effects across cortical areas.3
  • For context, a Frontiers systematic review and meta-analysis reported that visual cortex transcranial electrical stimulation increases cortical excitability (larger visual evoked potential amplitudes) versus sham, while noting that whether it changes GABA concentration in visual cortex remains unclear.4

Footnotes

  1. https://news.google.com/rss/articles/CBMilAFBVV95cUxNdVd6Z1lNMXQyR3YzZ0VvR3FUNHZpdklUOTM1YWdjUHdZM3lpcEc0VmR5Rlc0SGw0X2gyazlQU2MtRVI1eHpMalNWNTQ1a3lHQVlxZ3B0Mm1jMGN6N2h0Q1picGxPcDM5YjBoaG9wd0FQZXJ4SXUwdkxEV1R6SlE0bGdBTHYxXzU3Y2NwZWJveDBvdkM0?oc=5 ↩ ↩2 ↩3 ↩4

  2. https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2025.1639838/full ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  3. https://pmc.ncbi.nlm.nih.gov/articles/PMC12570334/ ↩ ↩2 ↩3 ↩4 ↩5

  4. https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2023.1119200/full ↩

Graph View