"Dwelling in the Past": The Role of Rumination in the Treatment of Posttraumatic Stress Disorder.

Prolonged exposure, a cognitive behavioral therapy including both in vivo and imaginal exposure to the traumatic memory, is one of several empirically supported treatments for chronic posttraumatic stress disorder (PTSD). In this article, we provide a case illustration in which this well-validated treatment did not yield expected clinical gains for a client with PTSD and co-occurring major depression. After providing an overview of the literature, theory, and treatment protocol, we discuss the clinical cascade effect that underlying ruminative processes had on the treatment of this case. Specifically, we highlight how ruminative processes, focusing on trying to understand why the traumatic event happened and why the client was still suffering, resulted in profound emotional distress in session and in a lack of an "optimal dose" of exposure during treatment.

Mental reinstatement of context and return of fear in spider-fearful participants.

Extant findings in the animal and human conditioning literature demonstrate that renewal, termed return of fear in studies with humans, occurs when reexposure to a previously feared phobic stimulus occurs in a context different than the one present during extinction. The present study investigated whether mental reinstatement of the treatment context at follow-up could attenuate context-based return of fear. Forty-eight spider-fearful individuals received exposure therapy in one of two contexts, and were followed-up 1 week later in the treatment or a new context. Half of the participants received instructions to mentally reinstate the treatment context before the follow-up test. Self-report data replicated previous research on contextually driven return of fear. Furthermore, participants who mentally reinstated the treatment context, before encountering the phobic stimulus in a new context at follow-up, had less return of fear than those who did not. Limitations of the current study, as well as implications for phobia treatment, are discussed.

Modality-specific attention under imminent but not remote threat of shock: evidence from differential prepulse inhibition of startle.

Theories of animal defensive behavior postulate that imminent, predictable threat elicits highly focused attention toward the threat source, whereas remote, unpredictable threat elicits distributed attention to the overall environment. We used threat of shock combined with measurement of prepulse inhibition of the startle reflex to test these claims in humans. Twenty-seven participants experienced periods of threat and safety. Threat and safe periods were short or long, with the short threat periods conveying relatively predictable, imminent shocks and the long threat periods conveying unpredictable shocks. Startle reflexes were elicited with equal numbers of acoustic probes presented alone, preceded by a tactile prepulse, or preceded by an auditory prepulse. We observed enhanced tactile relative to auditory prepulse inhibition during short threat periods only. This finding supports the notion that imminent threat, but not remote threat, elicits attention focused toward the relevant modality, potentially reflecting preparatory activity to minimize the impact of the noxious stimulus.

Sensitivity to masked conditioned stimuli predicts conditioned response magnitude under masked conditions.

Expression of conditioned fear has been reported to be independent of perceptual awareness of conditioned stimuli (CSs). Previous studies have been criticized, however, for not adequately assessing perceptual awareness. We fear-conditioned participants to one of two symbols and measured skin conductance responses to dichoptically masked and unmasked CSs. Participants also performed a target detection task and sensitivity (d') to the masked conditioned stimuli (CS+, CS-) was measured. Results showed that sensitivity under masking conditions was related to conditioned responses to masked CSs but not unmasked CSs. Thus, a strong relationship between expression of conditioned fear and awareness of the CS+ emerges when the latter is assessed by signal detection methods. Without consensus on how awareness should be defined, these findings bring balance to previous studies that have typically used less sensitive assessments of awareness.

Attentional blink and prepulse inhibition of startle are positively correlated.

Although a link between the attentional blink and prepulse startle inhibition has been considered, no evidence of this relationship has been reported. We delivered acoustic startle probes during rapid serial visual presentations in which the relative positions of two targets (targets 1 and 2) was varied within a stream of distractors. Startle probes were presented at 100 ms lead intervals relative to onset of a target or distractor. We found positive correlations between visual prepulse inhibition and attentional blink effects across participants. As the magnitude of prepulse inhibition with target and distractor lead stimuli increased, deficits in identifying target 2 during the attentional blink increased, suggesting similar processes underlying these phenomena. Whereas prepulse inhibition may reveal the strength of inhibition to protect stimulus processing, attentional blink may index the rate of recovery from similar inhibitory processes.