Grossman (2023) — Fundamental challenges and likely refutations of the five basic premises of the polyvagal theory
The critical source the wiki had lacked. Since the Payne (2015) ingest, polyvagal-theory was flagged as “contested in the wider literature… the wiki holds no critical source on it yet.” This is that source, read alongside its target (Porges 2023) — see the debate at is-polyvagal-theory-valid.
Paul Grossman (paul-grossman), a psychosomatic-medicine physiologist and long-time RSA methodologist, sets out to show that PVT’s physiological foundations — not its clinical appeal — are false, and that the behavioural corollaries therefore have nothing to stand on.
The five premises, dismantled
Grossman quotes Porges’s own five premises (Porges 2011) and argues each collapses:
- “Neurogenic bradycardia and RSA are mediated by different branches of the vagus.” The load-bearing claim, and the one modern methods most cleanly contradict. Selective ablation (Cheng), pharmacogenetic inhibition and optogenetic stimulation (Machhada et al. 2015–2020) converge: cardiac vagal control resides in the nucleus ambiguus; the DMNX contributes essentially nothing to heart rate. Veerakumar et al. (2022, Nature) state it flatly — the DMNX “does not control heart rate.” Strong optogenetic DMNX stimulation produced <7% heart-rate deceleration; a senior author estimated the same stimulation of the NA “is likely to stop the heart.” No profound DMNX-mediated bradycardia has ever been reported.
- Bradycardia as a reptilian DMNX vestige — depends entirely on Premise 1, so falls with it.
- Ventral/myelinated cardiac vagus as a mammalian invention — contradicted by comparative biology. Myelinated cardiac vagal B-fibres and ventral (NA) cardiac control are found across vertebrate classes; RSA-like coupling is documented in lungfish and rattlesnakes; reptiles show rich sociality. So neither RSA nor the ventral vagus nor sociality is uniquely mammalian.
- RSA as a monitor of general vagal tone — defeated by target-organ specificity (Jänig & Häbler): cardiac, pulmonary and gastric vagal outflows do not covary, so a cardiac index cannot report on the vagus at large. Farmer et al. (2016): inhibiting RSA left cardiac vagal tone largely intact — RSA and cardiac vagal tone are of “distinct origin.”
- Emotion → RSA/bronchomotor tone via nA — cardiac and bronchomotor vagal control are uncorrelated; emotional effects on RSA are largely respiration-mediated; “the nA and the vagus nerve are merely… the messenger, not the message.”
The category mistake
The paper’s sharpest general point, and the one most useful to this wiki: RSA is only an approximate index of cardiac vagal tone, under conditions (respiration must be controlled, since Katona & Jih 1975). Treating RSA as equal to cardiac vagal tone — let alone general vagal tone — is a Rylean category mistake: mistaking an aspect/index of a phenomenon for the phenomenon itself. Because a single measure (RSA/HF-HRV) is “the linchpin for virtually every premise,” the whole edifice inherits that measure’s limits. This is developed on respiratory-sinus-arrhythmia.
How to read it
The strongest available statement of the physiological case against PVT, from someone who has spent decades measuring RSA. Its force is that it does not argue from clinical taste but from ablation/optogenetic data and comparative anatomy, and reports a “broad consensus among experts” that each premise is untenable. Its limit is that it is a review, dismisses PVT’s non-cardiac claims as untestable rather than testing them, and is entangled in a bitter priority/attribution dispute with Porges. The wiki files the anatomy as strong evidence against PVT’s core mechanism while leaving the debate formally open (is-polyvagal-theory-valid) — Porges disputes that his premises say what Grossman quotes them as saying.