What is tonic immobility

They are responses we should expect from brains dominated by the circuitry of fear. It is critical for service providers to understand normal, protective responses to sexual violence such as tonic immobility. Survivors who experience tonic immobility are at greater risk for multiple negative mental health outcomes, and any bias or blame survivors perceive from service providers may be a major barrier these survivors receiving much-needed services.

Is there tonic immobility in humans? Biological evidence from victims of traumatic stress. Biological Psychology, 88 1 , Fear grips you as you struggle to assess what to do. Oftentimes, this paralysis is accompanied by a host of other characteristics too.

These can include the inability to vocalize, the inability to feel pain, tremors or muscle spasms, lowered heart rate, lower body temperature, and slower breathing. There are two crucial things to remember about tonic immobility. Someone going through this is aware of the traumatic event happening and does fully remember it, often in very vivid, sensory detail. Our brain has a deep, animal instinct that automatically turns on tonic immobility when the body receives certain danger cues; ultimately, this instinct is meant to protect us from harm.

So what are these two cues that turn on tonic immobility? Methods: This study had three main purposes: 1 to assess the factor structure of a new self-report measure--the Tonic Immobility Questionnaire--designed to assess human TI in a range of traumatic events; 2 to explore associations among discovered TIQ factors and a measure of posttraumatic symptoms in the context of trauma type; and 3 to determine whether TI is related to suspected and empirically supported predictors of posttraumatic stress disorder.

Results: No differences were found in frequency or severity of TI reported across trauma types. Sum scores in the four motor questions of the TI scale were calculated for each participant. A 2 x 80 ANOVA with one between group factor Group and one repeated measures factor Time was employed to compare the heart rate data between groups.

The Greenhouse-Geisser correction was applied to control for sphericity violation in the repeated measures factor. The results are reported with the original degrees of freedom, the corrected p values, and the effect sizes.

Scores differed significantly between the groups HIGH: Descriptive analysis of heart rate subtracted from baseline , after the exposure to the aversive noise, showed a larger and longer accelerative response in the HIGH than in the LOW TI group Figure 1. The peak of the acceleration occurs at second 3 after stimulus presentation.

Figure 1. Heart rate changes along 80 s after the noise stimulus, subtracted from mean baseline. Average increase in heart rate in the first 30 s was 7. This is the first study to investigate the modulation of the cardiac defense response in PTSD patients after the induction of a TI-like reaction in a laboratory setting.

PTSD patients who reported high levels of immobility after listening to their autobiographical trauma exhibited, upon exposure to the unexpected and intense auditory stimulus, a more pronounced and sustained accelerative cardiac defense response than patients who reported low levels or did not report at all signs of immobility.

Comparisons of PTSD symptoms scores between those with high and low scores of TI did not reach statistical significance, which favors TI as a main factor differentiating sustained versus transient tachycardia in response to the aversive sound. Recent research has been looking for the relationship between defensive reflex responses and psychopathology, investigating if different patterns of responsiveness can be associated with clinical conditions McTeague and Lang, Contributing with the RDoC initiative, Lang et al.

Schauer and Elbert proposed stages of defensive reactions in which TI, accompanied by the highest sympathetic activation, is at the peak of the fright stage. Alves et al. Volchan et al. The authors concluded that peritraumatic TI was experienced in the laboratory setting and was accompanied by tachycardia and lowering of vagal tone.

In the present study, PTSD patients displaying peritraumatic TI after exposure to trauma-script presented a pattern of cardiac defense response with more accelerative and sustained cardiac response indicating that they are more prone to cardiac sympathetic activation in response to varied aversive intense stimuli accompanied by reduced influence of the parasympathetic system.

This distinctiveness adds to a growing literature concerning peritraumatic TI symptoms which might indicate a specific PTSD subtype responding differently to pharmacological treatment Fiszman et al. Still, the present sample was small and PTSD patients were under medication.

Large scale randomized controlled trials are necessary to corroborate the promising findings. Written informed consent was provided by all participants, in accordance with the Declaration of Helsinki.

All the authors approved the final version of the manuscript and agreed to be accountable for all aspects of the work. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Alves, R. Exposure to trauma-relevant pictures is associated with tachycardia in victims who had experienced an intense peritraumatic defensive response: the tonic immobility. Google Scholar. Berger, W.