Tonic immobility

The freeze/collapse pole of the trauma response, entering the wiki via Payne et al. (2015) as part of Somatic Experiencing’s account of severe trauma. See peter-levine.

The core physiological claim: co-activation, not reciprocity

The ordinary picture of the ANS is reciprocal: sympathetic up, parasympathetic down, and back. SE’s inherited claim (from Gellhorn) is that this breaks down under extreme, inescapable stress. Gellhorn, working with anaesthetized cats, clamped the trachea to induce suffocation and observed first an extreme sympathetic rise, then an even greater co-activation of the parasympathetic — both branches firing hard at once. This co-activation is offered as:

• the physiology of tonic immobility (TI) — the innate motor-inhibition response shared by animals and humans under life threat;
• the substrate of the freeze, collapse, and dissociation of PTSD, and of the alternating “depressive shutdown ↔ anxiety/rage” oscillation SE describes;
• in polyvagal terms, the dorsal-vagal shutdown system co-activating with sympathetic mobilization.

If the co-activation claim is right, it is a genuine constraint on autonomic theory — a state the reciprocal model cannot produce — and it bears on autonomic-specificity (extreme states may be physiologically distinct in a way ordinary emotions may not be). The wiki holds it at one remove: it rests on Gellhorn’s mid-century animal work (said to be replicated by Paton et al. 2006) read through Levine’s thesis, with no primary-source physiology in raw/.

Human tonic immobility and its evidence

The paper connects TI to human data more cautiously than the rest of its claims: “rape-induced paralysis” (Galliano et al. 1993) and TI in traumatic-stress victims (Marx et al. 2008; Volchan et al. 2011). It also speculates — flagged as speculation in the text — that the trembling seen in TI is a thermogenic sympathetic priming of the muscles for a defensive response that never came, which SE then treats as the beginning of discharge to be encouraged rather than suppressed.

Where it sits in the wiki

• It gives the core-response-network its dysfunctional extreme: the CRN “locked into” high co-activation of both branches, oscillating erratically.
• It connects to survival-circuits: freeze/immobility is one of the defense circuit’s outputs (the “library” of species-specific defensive responses — orient, freeze, flee, fight, collapse), and TI is the collapse end of that library under conditions where action is impossible.
• It is the state biological-completion is meant to resolve at its deepest: not merely discharging excess sympathetic tone, but unlocking the co-activated freeze so a thwarted defensive movement can finally complete.

Filed as: a specific and physiologically striking claim (autonomic co-activation under extreme threat) that would matter if independently confirmed, held here on old animal evidence interpreted by parties with a therapeutic stake, and awaiting a primary source.