Intrusive memories – a hallmark symptom of posttraumatic stress disorder (PTSD) – are often triggered by stimuli possessing similarity with cues that predicted or accompanied the traumatic event. According to learning theories, intrusive memories can be seen as a conditioned response to trauma reminders. However, direct laboratory evidence for the link between fear conditionability and intrusive memories is missing. Furthermore, fear conditioning studies have predominantly relied on standardized aversive stimuli (e.g. electric stimulation) that bear little resemblance to typical traumatic events. To investigate the general relationship between fear conditionability and aversive memories, we tested 66 mentally healthy females in a novel conditioned-intrusion paradigm designed to model real-life traumatic experiences. The paradigm included a differential fear conditioning procedure with neutral sounds as conditioned stimuli and short violent film clips as unconditioned stimuli. Subsequent aversive memories were assessed through a memory triggering task (within 30 minutes, in the laboratory) and ambulatory assessment (involuntary aversive memories in the 2 days following the experiment). Skin conductance responses and subjective ratings demonstrated successful differential conditioning indicating that naturalistic aversive film stimuli can be used in a fear conditioning experiment. Furthermore, aversive memories were elicited in response to the conditioned stimuli during the memory triggering task and also occurred in the 2 days following the experiment. Importantly, participants who displayed higher conditionability showed more aversive memories during the memory triggering task and during ambulatory assessment. This suggests that fear conditioning constitutes an important source of persistent aversive memories. Implications for PTSD and its treatment are discussed.
HighlightsIntrusive memories can be seen as conditioned responses to trauma reminders.Novel conditioned-intrusion paradigm models both fear conditioning and intrusions.Low estradiol is related to higher conditioned responses during fear extinction.Low estradiol is related to higher intrusive memory strength in daily life.Conditioned responding during extinction partially explains the latter relationship.
Our findings point to a possible role of ABAT gene-regulated GABA catabolism for an altered processing of somatosensory stimuli as a potential vulnerability marker for affective disorders.
In der Forschung zu Entstehung und Aufrechterhaltung von Angststörungen stellt die Furchtkonditionierung ein gut etabliertes experimentelles Paradigma dar. Ein Problem früherer Konditionierungsstudien und der bisher verwendeten Angst auslösenden Reize ist jedoch ihre meist geringe externe Validität in Hinblick auf natürlich auftretende aversive Situationen und einen in der Realität ablaufenden Prozess des Angsterwerbs. In Anlehnung an das in der Angstforschung etablierte Traumafilm-Paradigma nutzten wir mehrere aversive Filmausschnitte, die die Konfrontation mit Angst auslösenden Inhalten möglichst naturalistisch simulieren sollen. Im Sinne einer klassischen, differenziellen Furchtkonditionierung paarten wir die Filmszenen (unkonditionierte Stimuli, UCS) mit Geräuschen (konditionierte Stimuli, CS) und untersuchten Erwerb sowie Extinktion der konditionierten Reaktionen. In Studie 1 wurde das neue experimentelle Paradigma erstmals implementiert und evaluiert. In Studie 2 wurde das Paradigma methodisch verbessert und schließlich basierend auf der Hautleitfähigkeitsreaktion (SCR) sowie der kontinuierlichen Erfassung des emotionalen Empfindens der Probanden validiert. Sowohl die Ergebnisse der SCR-Messungen als auch der Emotions-Ratings zeigten einen signifikanten differenziellen Angsterwerb sowie anschließende Extinktion. Die Ergebnisse bestätigen, dass das neue experimentelle Paradigma wichtige Kriterien einer Furchtkonditionierung erfüllt und ermutigen zu einem breiteren Einsatz naturalistischer Reize in Studien zur Entstehung von normalen Ängsten sowie Angststörungen.
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