title: Immobility reactions under threat: A contribution to human defensive cascade and PTSD.
abstract: Violence exacts a burden on public health. Gun violence is a major trigger for motor defensive reactions in humans and post-traumatic stress disorder (PTSD) is its main psychiatric sequela. However, studies of the human defensive cascade, especially the motor reactions, are at an early stage. This review focuses on studies that employ stabilometry, a methodology that assesses whole body motor reactions, to address defensive behaviors to violence-related threats. Special attention is given to three reactions: "attentive immobility", "immobility under attack" and "tonic immobility", with emphasis on the latter - a peritraumatic reaction which has been strongly associated with the severity of PTSD. These reactions are characterized by reduced body sway and bradycardia, except tonic immobility that presents robust tachycardia. The advances made by investigations into the immobility reactions of the human defensive cascade contribute to helping to bridge the gap between human and non-human species. Furthermore, progresses in basic research to objectively monitor motor defensive reactions under threat can help to develop a dimensional, trans-diagnostic approach to PTSD.
authors.affiliation: Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil. Electronic address: evolchan@biof.ufrj.br.
authors.forename: E
authors.initials: E
authors.lastname: Volchan
authors.affiliation: Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil; Instituto de Psiquiatria, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: V
authors.initials: V
authors.lastname: Rocha-Rego
authors.affiliation: Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: A F
authors.initials: AF
authors.lastname: Bastos
authors.affiliation: Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil; Instituto de Psiquiatria, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: J M
authors.initials: JM
authors.lastname: Oliveira
authors.affiliation: Instituto de Psiquiatria, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: C
authors.initials: C
authors.lastname: Franklin
authors.affiliation: Instituto de Psiquiatria, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: S
authors.initials: S
authors.lastname: Gleiser
authors.affiliation: Instituto de Psiquiatria, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: W
authors.initials: W
authors.lastname: Berger
authors.affiliation: Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Brazil.
authors.forename: G G L
authors.initials: GGL
authors.lastname: Souza
authors.affiliation: Instituto Biomédico, Universidade Federal Fluminense, Brazil.
authors.forename: L
authors.initials: L
authors.lastname: Oliveira
authors.affiliation: Instituto Biomédico, Universidade Federal Fluminense, Brazil.
authors.forename: I A
authors.initials: IA
authors.lastname: David
authors.affiliation: Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: F S
authors.initials: FS
authors.lastname: Erthal
authors.affiliation: Instituto Biomédico, Universidade Federal Fluminense, Brazil.
authors.forename: M G
authors.initials: MG
authors.lastname: Pereira
authors.affiliation: Instituto de Psiquiatria, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: I
authors.initials: I
authors.lastname: Figueira
mesh_terms: D003674:Defense Mechanisms; D006801:Humans; D046353:Immobility Response, Tonic; D013313:Stress Disorders, Post-Traumatic
keywords: Attentive immobility; Body sway; Defensive cascade; Freezing; Gun violence; Heart rate; Heart rate variability; Humans; Immobility under attack; Motor reaction; PTSD; Pictures; Posture; RDoC; Stabilometry; Threat; Tonic immobility; Trauma script