Neural Noise

TMS–EEG: prefrontal intracortical inhibition and cognitive dysfunction in post-COVID-19

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  • Disrupted intracortical inhibition in the prefrontal cortex relates to cognitive dysfunction in post-COVID-19 condition, as shown by TMS–EEG.1
  • The combination is methodologically relevant for TMS–EEG biomarkers and excitability assessment.1 1

Weekly enrichment (2026-07-20)

  • The study (Clinical Neurophysiology, Versace et al.) tested whether GABA_B-mediated intracortical inhibition, previously shown disrupted in motor cortex after COVID-19, is also altered in the prefrontal cortex, a region critical for cognition.2
  • Sample: 16 post-COVID-19 condition (pCVD) patients with cognitive complaints versus 12 healthy volunteers matched for gender, age, and education.2
  • Method: combined paired-pulse TMS–EEG measuring long-interval intracortical inhibition (LICI) over the left prefrontal cortex, with global cognition assessed by the Montreal Cognitive Assessment (MoCA).2
  • Patients showed lower TMS-evoked oscillatory activity and lower cognitive performance than controls (p < 0.05); crucially, healthy volunteers exhibited a normal LICI effect while pCVD patients showed no significant LICI in their oscillatory activity.2
  • Within patients, inhibition in the gamma (r = −0.479, p = 0.030) and beta (r = −0.478, p = 0.031) bands correlated linearly with cognitive performance, linking weaker prefrontal inhibition to worse cognition.2
  • Interpretation: GABA_B-receptor–mediated inhibitory control in the PFC is disrupted in pCVD patients with “brain fog”/dysexecutive symptoms, and TMS–EEG could serve as an early biomarker of subtle cortical/cognitive decline.2
  • Context: the same group previously reported GABAergic dysfunction (reduced LICI and intracortical facilitation) in the motor cortex of post-COVID patients with fatigue and dysexecutive syndrome, establishing the excitation/inhibition-imbalance hypothesis this study extends.3
  • Context: an FDG-PET/EEG study of post-COVID cognitive decline found frontotemporal hypometabolism plus EEG slowing (increased delta/theta, reduced alpha), consistent with disrupted GABAergic/glutamatergic balance.4
  • Context: a systematic review of non-invasive brain stimulation for post-COVID conditions reports early, mostly small/case-level evidence (e.g., ~27% cognitive-test improvement in one EEG-guided TMS case), underscoring that therapeutic use remains preliminary.5

Footnotes

  1. https://www.sciencedirect.com/science/article/pii/S1388245726002087?dgcid=rss_sd_all ↩ ↩2 ↩3

  2. https://pubmed.ncbi.nlm.nih.gov/41763093/ ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  3. https://doi.org/10.1016/j.clinph.2021.03.001 ↩

  4. https://www.nature.com/articles/s41598-025-04815-6 ↩

  5. https://doi.org/10.1016/j.amjmed.2024.07.007 ↩

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