Paul Grossman

Psychosomatic-medicine physiologist and long-time RSA methodologist; the wiki’s voice for the physiological case against Polyvagal Theory. Enters with Grossman (2023).

Position

Grossman’s expertise is the thing PVT is built on — how to measure RSA and what it does and does not mean — which is what makes his critique pointed. His core commitments:

• RSA is an index, not a phenomenon. It approximates cardiac vagal tone under controlled respiration and reports nothing about vagal outflow elsewhere, because of target-organ specificity. Treating it as “vagal tone” is a category mistake.
• The nucleus ambiguus does the cardiac work. Ablation, pharmacogenetic and optogenetic evidence place cardiac vagal control in the NA and essentially none in the dorsal motor nucleus — so PVT’s dorsal-vagal “massive bradycardia,” the source of the “poly,” has no experimental support.
• Nothing here is uniquely mammalian. With comparative physiologist E.W. Taylor, he argues the ventral vagus, myelinated cardiac vagal fibres, RSA-like coupling and complex sociality all predate mammals — dissolving PVT’s evolutionary story.

How to read him in this wiki

The strongest available counterweight to Porges, and a genuine subject-matter expert rather than a hostile outsider — his verdict is that a “broad consensus” of vertebrate-ANS specialists regards each PVT premise as untenable (is-polyvagal-theory-valid). Two cautions. First, his 2023 paper is a review that marshals others’ data rather than a decisive experiment, and it explicitly sets aside PVT’s non-cardiac claims as untestable rather than refuting them. Second, the exchange is personal: Grossman edited the Biological Psychology special issue of PVT critiques, and Porges accuses Grossman & Taylor of a strawman and of unattributed paraphrasing (walked back in a corrigendum). The wiki weights his anatomy heavily and reads the polemic on both sides at a discount.