Memory control ability modulates intrusive memories after analogue trauma

AbstractBackgroundMost people suffer from intrusive memories in the aftermath of trauma. For survivors' well-being, it is key that these intrusions are controlled. Memory control can be exerted through retrieval suppression. Poor retrieval suppression, however, should be associated with persistent distressing intrusions and posttraumatic stress disorder (PTSD). This study tested the hypothesis that individual differences in retrieval suppression predict intrusive memories after trauma. Retrieval suppression was examined with the think/no-think task (TNT) using behavioral and event related potential (ERP) measures.MethodsTwenty-four healthy participants watched a “traumatic” film after performing the TNT task. The frequency and distress of intrusions from the “traumatic” film was measured with an electronic diary. Additionally the Impact of Event Scale (IES) was assessed.ResultsIn line with our hypothesis, behavioral measures of retrieval suppression ability predicted reduced distress ratings for intrusions (r=−.53, p<.01). Further ERP markers of retrieval suppression (a fronto-centrally distributed N2) predicted reduced distress ratings for intrusions (r=−.45, p<.05) and reduced IES Intrusion scores (r=−.56, p<.01).LimitationsThe presented film is a relatively mild stressor as compared to a real-life trauma. Further studies are needed to explore the role of memory control processes for real-life trauma.ConclusionsParticipants with lower retrieval suppression ability exhibited less distressing intrusive memories after analogue trauma. The ERP correlate of retrieval suppression was associated with less distressing intrusive memories and reduced IES Intrusion scores, suggesting that deficient memory control is a potential risk factor for developing PTSD

Public Sector Employment Regimes : Transformations of the State as an Employer

Public employment regimes are changing. New forms of service provision based on performance assessment have replaced the traditional model of the civil servant who offers obedience and loyalty in exchange for privileged employment conditions. This book explores the extent to which the material and ideological driving forces of change have actually resulted in a transformation of public employment regimes in Western countries. By analyzing reform processes in energy market regulation, waste collection, and the police in Germany, France, and Sweden, and contrasting these against the implementation of New Public Management in the United Kingdom, the authors show how institutional structures, legal traditions, functional requirements of specific public services, and labour market conditions have influenced the pathways of reform. They demonstrate how public employment regimes have unravelled in different domains of public service, contesting the idea that the state remains a 'good' and 'model' employer

Therapy Dogs as a Crisis Intervention After Traumatic Events? – An Experimental Study

Animal-assisted therapy has been proposed as a treatment adjunct for traumatized patients. In animal-assisted crisis response, dogs are used directly after a traumatic event to reduce stress and anxiety. However, to date there are few controlled studies investigating the effects of therapy dogs on PTSD symptoms and to our knowledge there is no study investigating the effects of a therapy dog intervention directly after a traumatic event. In this study, 60 healthy female participants were randomly assigned to one of three groups: after exposure to a “traumatic” film clip (trauma-film paradigm), one group of participants interacted with a friendly dog for 15 min, another group of participants watched a film clip showing a person interacting with a friendly dog and the last group was instructed to relax. Participants who had interacted with the dog after the film reported lower anxiety levels, less negative affect, and more positive affect after the intervention as compared to the other two groups. However, the participants who interacted with the dog showed a smaller decrease in physiological arousal after the traumatic film clip compared to both other groups. There were no differences in intrusion symptoms between the three groups. Our results show that dogs are able to lessen subjectively experienced stress and anxiety after a “traumatic” stress situation

Untersuchung der Gedächtnisprozesse, die intrusiven Trauma-Erinnerungen zugrunde liegen : der Einfluss von Gedächtnisabruf-Unterdrückung und Assoziativem Lernen

The global aim of this thesis was to examine the mechanisms underlying intrusive memories after traumatic events. As recent findings suggest that deficits in the ability to voluntarily inhibit memory retrieval are related to posttraumatic stress disorder (PTSD) symptom severity, the studies included in this work tested whether deficits in retrieval suppression constitute a potential cognitive risk factor that leads to an increase in intrusive memories after traumatic events. Furthermore, these studies investigated whether the same neural process that mediates retrieval suppression is also associated with fewer trauma memories. Since current research indicates that intrusive trauma memories can occur as conditioned responses to trauma reminders, another aim of this thesis was to further examine the role of conditioning in the development and maintenance of intrusive trauma memories. Specifically, the temporal stability of conditioned reactions was investigated. An additional aim of this thesis was to test whether conditioned responses are reduced after imaginal exposure, as has been suggested by current models of PTSD. Study 1 was designed to test whether pre-existing deficits in memory control constitute a potential cognitive risk factor for intrusive memories after traumatic events, and whether the neural processes underlying memory control are also involved in controlling intrusive trauma memories. Suppression-induced forgetting, an index of memory control, was found to be associated with subjective distress experienced during intrusive memories of a traumatic film. Furthermore, the neural correlate of the inhibitory control process which is supposed to underlie suppression-induced forgetting (i.e. N2 ERP component) was also associated with a reduction in the degree of distress of intrusive memories, as well as a reduction in other analogue PTSD symptoms. These findings indicate that the pre-existing ability to suppress memory retrieval may be beneficial for recovering from intrusive memories after traumatic events. Furthermore, the findings indicate that the same inhibitory control process that was found to mediate retrieval suppression and stopping a prepotent motor response may also be involved in controlling the automatic retrieval of intrusive trauma memories. Study 2 aimed to investigate whether conditioned responses to trauma-associated stimuli are stable over time and whether they are affected by imaginal exposure. Indeed, intrusive memories and subjective fear as a reaction to trauma-associated stimuli were observed and remained stable over the entire assessment period of one week, providing further evidence for the assumption that conditioning plays a crucial role in the development and maintenance of intrusive memories after traumatic events. Furthermore, conditionability of subjective indices was associated with subsequent ambulatory intrusive memories, however, physiological parameters assessing emotional arousal as a reaction to trauma reminders did not show these effects. Moreover, imaginal exposure had no impact on conditioned responses to trauma-associated stimuli or intrusive trauma memories.Das Ziel dieser Arbeit war die Untersuchung der Mechanismen, die intrusiven Erinnerungen nach traumatischen Ereignissen zugrunde liegen. Da neuere Befunde darauf hindeuten, dass Defizite in der Fähigkeit, willentlich den Gedächtnisabruf zu inhibieren mit der Ausprägung von Symptomen der Posttraumatischen Belastungsstörung (PTBS) zusammenhängen, wurde in der vorliegenden Arbeit untersucht, ob Defizite in der Inhibition des Gedächtnisabrufs einen potentiellen kognitiven Risikofaktor für ein vermehrtes Auftreten intrusiver Erinnerungen nach traumatischen Ereignissen darstellt. Des Weiteren wurde untersucht, ob derselbe neuronale Prozess, welcher der Inhibition des Gedächtnisabrufs zugrunde liegt, ebenfalls mit reduzierten Trauma-Erinnerungen assoziiert ist. Nachdem aktuelle Forschungsbefunde darauf hindeuten, dass intrusive Trauma-Erinnerungen als konditioniere Reaktionen auf Trauma-Hinweisreize auftreten können, ist ein weiteres Ziel dieser Arbeit, die Rolle von Konditionierungsprozessen bei der Entstehung und Aufrechterhaltung intrusiver Trauma-Erinnerungen zu untersuchen. Dabei wurde insbesondere die zeitliche Stabilität der konditionierten Reaktionen analysiert. Ein zusätzliches Ziel dieser Arbeit war es, herauszufinden ob konditionierte Reaktionen, wie von aktuellen Modellen der PTBS angenommen, durch imaginative Exposition reduziert werden können. Studie 1 wurde konzipiert, um zu überprüfen, ob vorherbestehende Defizite in der Inhibition des Gedächtnisabrufs, einen potentiellen kognitiven Risikofaktor intrusiver Erinnerungen nach traumatischen Ereignissen darstellen und ob dieselben neuronalen Prozesse, die der Inhibition des Gedächtnisabrufs zugrunde liegen, ebenfalls an der Kontrolle intrusiver Trauma-Erinnerungen beteiligt sind. Suppressionsinduziertes Vergessen, ein Index für die Fähigkeit zur Inhibition des Gedächtnisabrufs, war assoziiert mit der Belastung während später auftretenden intrusiven Erinnerungen an einen traumatischen Film. Des Weiteren, war das neuronale Korrelat des inhibitorischen Kontrollprozesses, von dem angenommen wird, dass er suppressionsinduziertem Vergessen zugrunde liegt (die N2 EKP-Komponente), ebenfalls mit einer Reduktion der Belastung durch intrusive Erinnerungen und einer Reduktion analoger PTBS-Symptome assoziiert. Diese Befunde deuten an, dass die vorherbestehende Fähigkeit den Gedächtnisabruf zu inhibieren förderlich für die Rückbildung intrusiver Erinnerungen nach traumatischen Ereignissen sein könnte. Darüber hinaus, deuten die Befunde darauf hin, dass derselbe inhibitorische Kontrollprozess, welcher bereits mit der Inhibition des Gedächtnisabrufs und der Unterbrechung einer vorherrschenden motorischen Reaktion in Verbindung gebracht wurde, ebenfalls an der Kontrolle des automatischen Gedächtnisabrufs intrusiver Trauma-Erinnerungen beteiligt sein könnte. Ziel von Studie 2 war es zu untersuchen, ob konditionierte Reaktionen auf trauma-assoziierte Stimuli zeitlich stabil sind und ob sich diese durch imaginative Exposition verändern lassen. Tatsächlich traten intrusive Erinnerungen und subjektive Furcht als Reaktion auf trauma-assoziierte Stimuli über den gesamten Erhebungszeitraum von einer Woche auf, was weitere Belege für die Annahme liefert, dass Konditionierungsprozesse eine entscheidende Rolle bei der Entstehung und Aufrechterhaltung intrusiver Erinnerungen nach traumatischen Ereignissen spielen. Des Weiteren war die Konditionierbarkeit der subjektiven Maße mit später auftretenden ambulanten intrusiven Erinnerungen assoziiert, wohingegen psycho-physiologische Parameter, welche emotionale Erregung als Reaktion auf die Trauma-Hinweisreize erfassten, keine dieser Effekte zeigten. Die imaginative Exposition hatte darüber hinaus keinen Einfluss auf die konditionierten Reaktionen auf trauma-assoziierte Stimuli oder intrusive Trauma-Erinnerungen

Effects of acute cortisol administration on perceptual priming of trauma-related material

Intrusive memories are a hallmark symptom of posttraumatic stress disorder (PTSD). They reflect excessive and uncontrolled retrieval of the traumatic memory. Acute elevations of cortisol are known to impair the retrieval of already stored memory information. Thus, continuous cortisol administration might help in reducing intrusive memories in PTSD. Strong perceptual priming for neutral stimuli associated with a “traumatic” context has been shown to be one important learning mechanism that leads to intrusive memories. However, the memory modulating effects of cortisol have only been shown for explicit declarative memory processes. Thus, in our double blind, placebo controlled study we aimed to investigate whether cortisol influences perceptual priming of neutral stimuli that appeared in a “traumatic” context. Two groups of healthy volunteers (N = 160) watched either neutral or “traumatic” picture stories on a computer screen. Neutral objects were presented in between the pictures. Memory for these neutral objects was tested after 24 hours with a perceptual priming task and an explicit memory task. Prior to memory testing half of the participants in each group received 25 mg of cortisol, the other half received placebo. In the placebo group participants in the “traumatic” stories condition showed more perceptual priming for the neutral objects than participants in the neutral stories condition, indicating a strong perceptual priming effect for neutral stimuli presented in a “traumatic” context. In the cortisol group this effect was not present: Participants in the neutral stories and participants in the “traumatic” stories condition in the cortisol group showed comparable priming effects for the neutral objects. Our findings show that cortisol inhibits perceptual priming for neutral stimuli that appeared in a “traumatic” context. These findings indicate that cortisol influences PTSD-relevant memory processes and thus further support the idea that administration of cortisol might be an effective treatment strategy in reducing intrusive reexperiencing

Sensitivity (d’) and response bias (c) in the recognition memory test in the four conditions.

<p>Sensitivity (d’) and response bias (c) in the recognition memory test in the four conditions.</p

Example of a neutral and a “traumatic” picture story including the presented priming objects.

<p>Example of a neutral and a “traumatic” picture story including the presented priming objects.</p

Cortisol effects on perceptual priming: In the placebo group participants in the “traumatic” stories condition showed more perceptual priming for the neutral objects than participants in the neutral stories condition, indicating a strong perceptual priming effect for neutral stimuli presented in a “traumatic” context.

<p>In the cortisol group this effect was not present: Participants in the neutral stories and participants in the “traumatic” stories condition in the cortisol group showed comparable priming effects for the neutral objects.</p