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SRC - The Vagus Nerve

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SRC - The Vagus Nerve

Folder: 05 - SOURCE MATERIAL Supporting: The Vagus Nerve

Primary Research

ScienceDirect — November 2024 “The vagus nerve: An old but new player in brain-body communication” https://www.sciencedirect.com/science/article/pii/S0889159124007050 Confirms: 2024 Jin et al. immune circuit discovery. NST neurons activated by immune triggers via vagus. Chemogenetic stimulation enhanced survival in lethal inflammatory conditions.

PMC — Breit et al. (2018) “Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders” https://pmc.ncbi.nlm.nih.gov/articles/PMC5859128/ Confirms: primary function afferent (80% sensory fibres). Inner organs as major sensory sources to brain confirmed. Parasympathetic functions documented. VNS as treatment for depression and inflammatory conditions.

PMC — PMC9656367 (2022) “Vagus Nerve and Underlying Impact on the Gut Microbiota-Brain Axis in Behavior and Neurodegenerative Diseases” https://pmc.ncbi.nlm.nih.gov/articles/PMC9656367/ Confirms: 80% afferent fibres. Gut microbiota-brain axis via VN. Bidirectional communication documented. Behavioural changes from gut microbiota alterations confirmed.

PMC — VNS Review (2024) “A Review of Vagus Nerve Stimulation for Disease: Comprehensive Theory and Evidence for Mechanisms of Action” https://pmc.ncbi.nlm.nih.gov/articles/PMC12960021/ Confirms: VN interfaces brainstem, heart, lungs, spleen, stomach, intestine, kidney. VNS modulates memory, learning, attention. BDNF expression and hippocampal LTP confirmed.

Vagal Tone and HRV

MDPI — December 2025 “Integrative Neuroimmune Role of the Parasympathetic Nervous System, Vagus Nerve and Gut Microbiota in Stress Modulation” https://www.mdpi.com/1422-0067/26/23/11706 Confirms: reduced vagal tone associated with anxiety, depression, PTSD. HRV as indicator of resilience and vulnerability. Gut microbiota role in stress modulation confirmed.

The Heart and Aging

Science Translational Medicine — January 1, 2026 Dushpanova et al. “Reconnecting the vagus nerve to the heart through nerve conduit preserves cardiac function in a minipig model of right cardiac vagotomy” Science Translational Medicine, 17 (830). DOI: 10.1126/scitranslmed.aea4306 https://www.sciencedaily.com/releases/2025/12/251225235946.htm Confirms: vagal connection to heart slows cardiac aging. Partial restoration sufficient to slow harmful tissue changes. Cardiac function preserved.

Gut-Brain Axis

Northwell Health / Feinstein Institute — February 7, 2025 https://feinstein.northwell.edu/news/insights/gut-brain-axis-vns Confirms: gut contains most vagus nerve sensory endings. More information passed between gut and brain than any other systems. ENS contains second largest neural network after brain.

Journal of Neurophysiology — American Physiological Society (2024) “The Vagus Connection: Exploring the Neurobiology of Brain-Gut Communication” https://journals.physiology.org/doi/abs/10.1152/jn.00516.2024 Confirms: motor division originates from brainstem nuclei. Sensory inputs to NTS confirmed. Stress disrupts excitatory-inhibitory balance in DMV. VNS as therapeutic approach for gut and cognitive function.

Polyvagal Theory

Stephen Porges — Polyvagal Theory Porges, S.W. (2011) The Polyvagal Theory: Neurophysiological Foundations of Emotions, Attachment, Communication, and Self-regulation. W.W. Norton & Company. Primary source for the framework.

PubMed — Porges (2025) “Disorders of gut-brain interaction through the lens of polyvagal theory” https://pubmed.ncbi.nlm.nih.gov/39344751/ Most current Porges publication. Vagal efficiency as clinical metric. Brainstem switching mechanism proposed.

Honest caveat: Polyvagal Theory’s specific neuroanatomical claims debated in academic literature. Clinical applications have significant support. Specific mechanisms under review. Tag: credible — not verified

Slow Breathing and VNS

Frontiers in Human Neuroscience Multiple studies on slow breathing and HRV / vagal tone. 5–6 breaths per minute as optimal documented across multiple labs. Exhalation-emphasis confirmed as key mechanism.

Still To Source

  • Cold exposure and diving reflex — peer reviewed studies on vagal activation mechanism #investigate
  • Humming/singing vagal stimulation — peer reviewed primary citations beyond clinical VNS literature investigate
  • Serotonin gut production percentage — 90% figure confirm primary citation investigate
  • Gut microbiome and neurotransmitter production — dopamine and GABA primary studies investigate
  • EMF effects on vagal tone — peer reviewed studies on chronic WiFi/cellular exposure and HRV specifically investigate
  • Polyvagal Theory anatomical challenges — primary neuroanatomy papers contesting specific claims investigate

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