A critical question remains: what is happening peri-traumatically at a neural level while witnessing scenes that later intrude involuntarily? One person may report flashbacks to a scene where a fireman carried a baby, whereas another may flash back to a man's face covered in blood. However, as with real-life trauma, individual responses to the same trauma film are highly idiosyncratic. Healthy individuals often experience several flashbacks during the following week. Afterwards, a diary is used to record involuntary flashbacks of segments of the film. Healthy individuals watch a film depicting traumatic events such as actual or threatened death or serious injury. To this end, the trauma film paradigm is a well-established method used as an analogue model of psychological trauma (Horowitz, 1969 Holmes et al. It is clearly difficult to study people during real trauma for ethical and practical reasons. Thus, to understand flashback aetiology, we need to examine processing during trauma encoding. However, different processes may be involved peri-traumatically and post-traumatically. Data relating to hippocampal function in PTSD are less clear, with some studies showing decreased function but others increased function (Francati et al. ![]() These findings have been replicated in functional magnetic resonance imaging (fMRI), positron emission tomography (PET) and single photon emission computed tomography (SPECT) studies (Hughes & Shin, 2011). ( 1996) reported increased blood flow for traumatic scripts compared with neutral scripts in limbic and paralimbic areas, including the amygdala. Using a similar methodology, Rauch et al. ![]() Compared with veterans without PTSD, those with the disorder had reduced activity in the medial prefrontal cortex and increased activity in the amygdala. Script-driven imagery (playing back a patient's narrative of a neutral or traumatic event) was used to provoke PTSD symptoms. ( 2004) used positron emission tomography with 17 Vietnam veterans with PTSD, and 19 without. ![]() 1998, 2006) highlights robust findings of reduced activity in ventromedial prefrontal regions, combined with increased activity in limbic regions. Thus, there is no direct data to predict which brain regions may be involved in flashback aetiology, though patient studies may be informative.Ī neurocircuitry model of PTSD (Rauch et al. after flashbacks have already been established. Studies using PTSD patients can only inform on post-traumatic processes, i.e. However, neuroscientific data on the peri-traumatic phase are lacking. The importance of psychological processing at the time of trauma (peri-traumatic) is emphasized by the diagnostic criteria for PTSD (APA, 1994), clinical psychology theories (Conway & Pleydell-Pearce, 2000 Ehlers & Clark, 2000 Brewin & Holmes, 2003) and meta-analysis of PTSD predictors (Ozer et al. A key question is why some moments but not others become flashbacks? A neuroscientific approach raises the possibility that there may be differences in brain processing at the very time of experiencing the original trauma that predict which events within the trauma will subsequently become flashbacks. However, the moment when he witnessed a comrade's arm being blown-off may repeatedly flash back. But these memories, despite being highly distressing, may never involuntarily intrude. For example, a soldier may regularly experience traumatic scenes, such as of dead bodies or firefights. Flashback memories tend to be of distinct moments within an event, rather than of the whole trauma from start to finish. ![]() Not all memories of trauma become flashbacks (Grey & Holmes, 2008). That is, a ‘flashback’ is ‘a mental vision of a past experience’ (Stein et al. Here we use the term ‘flashbacks’ to describe vivid, sensory–perceptual (predominantly visual images) emotional memories from a traumatic event that intrude involuntarily into consciousness. The former, and much more common, intrusive memories are clinically important in the maintenance of PTSD (Ehlers & Clark, 2000 Foa et al. Intrusive, involuntary memories range from fleeting sensory impressions of traumatic events, to (very rarely) full-blown flashbacks which are so intense the patient dissociates and feels as if they are back at the time of the trauma. The hallmark PTSD symptom is the re-experiencing of the trauma in the form of intrusive memories (APA, 1994). A small but clinically significant proportion of people who experience a trauma subsequently develop PTSD (Kessler et al. Traumatic events include war, terrorist attacks, interpersonal violence and natural disasters (WHO, 2003). Post-traumatic stress disorder (PTSD) is the only psychiatric disorder for which a specific event and experience (the trauma and concurrent reaction) form part of the diagnosis (APA, 1994).
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