​STUDIES on the brain and non-invasive stimulation such as tACs, tDCs, tRMS, and LEDS

Here are 10 peer-reviewed studies showing direct brain effects for tACS, tDCS, tRNS, and transcranial LEDs/photo bio modulation  (tPBM).

tDCS (transcranial Direct Current Stimulation)

1. Nitsche & Paulus, 2000 — Anodal vs. cathodal tDCS over human M1 bidirectionally modulates corticospinal excitability (MEPs). https://physoc.onlinelibrary.wiley.com/doi/abs/10.1111/j. 1469-7793.2000.t01-1-00633.x
2. Lang et al., 2004 — M1 tDCS produces lasting changes in cortical excitability, including interhemispheric effects measured with TMS. https://pubmed.ncbi.nlm.nih.gov/14745467/
3. Pellicciari et al., 2013 — Polarity-specific modulation of motor system reactivity by tDCS, showing complex direct/indirect effects. https://www.sciencedirect.com/science/article/abs/pii/S1 053811913007192

tACS (transcranial Alternating Current Stimulation)

1. Helfrich et al., 2014 (Current Biology) — 10 Hz tACS entrains alpha oscillations and synchronizes cortical oscillators (EEG/MEG). https://www.sciencedirect.com/science/article/pii/S096098221301600X
2. Vossen et al., 2015 (PLOS ONE) — Alpha-power increases after tACS, consistent with direct entrainment and/or plastic changes.  https://pmc.ncbi.nlm.nih.gov/articles/PMC4464304/
3. Ali et al., 2013 (J. Neurosci.) — tACS modulates targeted cortical oscillations linked to motor/cognitive functions.  https://www.jneurosci.org/content/33/27/11262

tRNS (transcranial Random Noise Stimulation)

1. Terney et al., 2008 (J. Neurosci.) — High-frequency tRNS over M1 increases cortical excitability (MEP amplitudes)  for ~60 min.  https://www.jneurosci.org/content/28/52/14147 (PDF: https://www.jneurosci.org/content/jneuro/28/52/14147.full.pdf)
2. Moret et al., 2019 (Sci. Reports) — Parameterized hf-tRNS robustly enhances neural excitability (MEP changes) and performance. ​https://www.nature.com/articles/s41598-019-51553-7 (PDF alt: https://www.research.unipd.it/bitstream/11577/3317638/1/Moret%20et%20al.%202019.pdf)

LEDs / tPBM (transcranial photobiomodulation)

1. Zomorrodi et al., 2019 (Sci. Reports) — Transcranial + intranasal NIR PBM modulates EEG neural oscillations in humans. ​https://www.nature.com/articles/s41598-019-42693-x 
2. Chaudhari et al., 2023 (Bioengineering) — Four weeks of prefrontal LED-tPBM alters EEG network power (theta/beta/gamma) and improves vigilance. https://pmc.ncbi.nlm.nih.gov/articles/PMC10525861/ (journal page: https://www.mdpi.com/2306-5354/10/9/1043)