Neural Noise

tDCS peripheral nerve stimulation and passive avoidance learning in rats

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  • tDCS applied to peripheral nerve can enhance passive avoidance learning in rats.1
  • The finding is preclinical and peripherally focused; it is tangential to central BCI/neuromodulation but relevant for stimulation methods.1 1

Gardner updates

  • tDCS applied to peripheral nerve enhanced passive avoidance learning in rats (Frontiers); preclinical, peripheral focus. 1

Weekly enrichment (2026-07-20)

  • The primary source is a 2025 Frontiers in Neuroscience study (DOI 10.3389/fnins.2025.1623434, Volume 19) using a minimally restrictive rat model that separates the tDCS electric field in the brain (transcranial pathway) from the skin (transcutaneous pathway) via epicranial and subcutaneous electrodes.2 3
  • Subjects were male Sprague–Dawley rats aged 5–8 weeks (KU Leuven ethics approval): experiment 1 used n = 16 per group across four groups (regular tDCS, transcutaneous-only, transcranial-only, sham) and experiment 2 used n = 13 per group across two groups (transcutaneous-only and sham), with experimenters blinded to group.2
  • In experiment 1 at 0.25 mA, none of the stimulation conditions significantly improved passive avoidance task (PAT) memory retention versus sham, a non-replication of earlier reports (Yu et al., 2019; Jung et al., 2019) that 0.25 mA anodal tDCS enhances PAT learning.2 3
  • In experiment 2, 30 minutes of transcutaneous-only direct-current stimulation at 2 mA (an amplitude closer to human tDCS), with the cathodal electrode over the third occipital nerve, significantly improved PAT learning.2 3
  • Stimulation was delivered for 30 min using an A-M Systems Model 2200 current stimulator through subcutaneous conductive-rubber disk electrodes (⌀ 10 mm); sham ramped current for only ~3 s while cables stayed connected.2
  • The proposed mechanism is that peripheral (occipital nerve) activation engages the ascending reticular activating system and locus coeruleus noradrenergic pathway, which facilitates hippocampal memory formation, rather than the effect arising solely from the intracerebral field.2 4
  • Prior work cited as context found 0.25 mA tDCS increased hippocampal CA1 long-term potentiation and BDNF (Yu et al., 2019) and that benefits appeared only when stimulation preceded the acquisition (not retrieval) phase (Jung et al., 2019); isolated occipital and vagus nerve stimulation have separately improved PAT retention.2 4
  • BCI/neuromodulation implication: DC stimulation of peripheral nerves can by itself modulate learning and memory, supporting the view that transcutaneous peripheral-nerve activation is a genuine contributing mechanism of tDCS effects, not merely a sensory side effect, with relevance to how human tDCS outcomes are interpreted.2 3

Footnotes

  1. https://news.google.com/rss/articles/CBMilAFBVV95cUxOUGhNMVNMWHI0NUxuZVRjNmd6T0d2ZHlTWVRGem9kU2ZBYzNKVnF6bVN6STlsWkVzTUZtZWI2NUcwQURJcXQydnRtRzhteEZKMUZnU0xyNHNVZ2kxTmJ0ZTEwNHcwS3BBTTNKc1pFek5PVVF1SDhXcDRoRlJLaExHenZhZUZjRTByUzJnSXA0M2oxUFJz?oc=5 ↩ ↩2 ↩3 ↩4

  2. https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2025.1623434/full ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8

  3. https://doi.org/10.3389/fnins.2025.1623434 ↩ ↩2 ↩3 ↩4

  4. https://www.tcd.ie/media/tcd/psychology/pdf/The-peripheral-effect-of-direct-current-stimulation-on-brain-circuits-involving-memory.pdf ↩ ↩2

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