Neural Noise

tES-fNIRS closed-loop framework for response inhibition

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  • A novel tES-fNIRS framework combines transcranial electrical stimulation and fNIRS for closed-loop enhancement of response inhibition.1
  • The methods are applicable to non-invasive BCI and neurofeedback.1 1

Weekly enrichment (2026-07-20)

  • The framework corresponds to Lu, Cheng et al. (Scientific Reports, 2025, s41598-025-23578-8), which combined transcranial electrical stimulation with simultaneous fNIRS monitoring of the prefrontal cortex in 229 healthy male adults randomized to tACS, tDCS, or sham groups across two experiments (Experiment 1 n=105 behavioral, Experiment 2 n=124 with fNIRS).2
  • Stimulation used a Soterix Medical MxN-33 high-definition stimulator with 12 mm electrodes in a 4×1 surround montage centered on FC6 over the right inferior frontal gyrus (returns at F6, FT8, C6, FC4), delivering 1.5 mA for 10 min; tACS was applied at 20 Hz (beta band) and sham ramped over 60 s.2
  • Both tDCS and tACS significantly reduced the Stroop effect versus sham (group×time interaction F(2,102)=4.144, P=0.019, ηp²=0.075); post-intervention Stroop effect fell to 65.3±45.5 ms for tDCS and 70.1±43.4 ms for tACS, with the tDCS-vs-tACS difference not statistically significant.2
  • fNIRS (LABNIRS, 14 channels at 780/805/830 nm, 27.78 Hz sampling) showed tDCS uniquely reduced oxy-Hb activation in frontal-pole channels 7 and 10 during stimulation (channel 7 F(2,121)=3.627, P=0.030; channel 10 F(2,121)=4.116, P=0.019), interpreted as improved neural efficiency, with no equivalent change under tACS.2
  • Functional connectivity within the PFC (Pearson/Fisher-z on HbO₂) decreased significantly after tDCS, consistent with the hypothesis that inhibitory control improves via more efficient rather than more extensive neural communication.2
  • Double-blinding was verified: no significant difference in correct guesses of active-vs-sham allocation across groups (Experiment 1 χ²(4)=1.02, P=0.907; Experiment 2 χ²(4)=3.85, P=0.427), and reported side effects (itching, distraction, headache, sleepiness) were mild and transient.2
  • The authors note limitations relevant to any closed-loop tES-fNIRS BCI: an all-male sample, fixed literature-derived stimulation parameters rather than individualized dosing, limited fNIRS channel coverage of the IFG, and neurovascular decoupling whereby 20 Hz tACS entrainment may not map cleanly onto hemodynamic readouts.2
  • Commercial integrated platforms already enable this modality — e.g. the Neuroelectrics Starstim combined with Artinis fNIRS in a single headcap — supporting real-time closed-loop protocols that adjust tES parameters to individual brain-state dynamics; related closed-loop tES-fMRI work optimizes tACS frequency and phase to maximize frontoparietal synchronization.3 4

Footnotes

  1. https://news.google.com/rss/articles/CBMiX0FVX3lxTE9XN0tuTE9rdTdpVk5Yb0stazBuOHZjQzAwMF9MbHVUVnliem45WWpUdjIzYXFKazI4N0R0VlpDWDR1R0s2dkJONDcxUmx5eUdxbE85UGxjSTI4ek1aQzl3?oc=5 ↩ ↩2 ↩3

  2. https://www.nature.com/articles/s41598-025-23578-8 ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7

  3. https://artinis.com/blogpost-all/2022/the-starstim-fnirs-combining-tes-brain-stimulation-and-eeg-fnirs-neuroimaging-in-one-headcap ↩

  4. https://doi.org/10.1002/brb3.2667 ↩

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