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Exposure therapy consists of exposing patients to their fears and thereby diminishing their harm expectancies (i.e., extinction or expectancy learning). Although effective for many anxiety patients, its long-term success depends on the generalization of these harm expectancies to other stimuli. However, research shows that this generalization of extinction is limited. Besides decreasing harm expectancies, fear reduction may also be achieved by changing the meaning of an aversive memory representation (US revaluation). Imagery rescripting (ImRs) may be more successful in generalizing fear reduction because it allegedly works through US revaluation. The current experiment aimed to test working mechanisms for ImRs and extinction (revaluation and expectancy learning, respectively), and to examine generalization of fear reduction. In a fear conditioning paradigm, 113 healthy participants watched an aversive film clip that was used as the US. The manipulation consisted of imagining a script with a positive ending to the film clip (ImRs-only), extinction (extinction-only), or both (ImRs + extinction). Results showed enhanced US revaluation in ImRs + extinction. US expectancy decreased more strongly in the extinction conditions. Generalization of fear reduction was found in all conditions. Our results suggest different working mechanisms for ImRs and exposure. Future research should replicate this in (sub)clinical samples.

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BACKGROUND AND OBJECTIVES: To understand how memories of negative events become highly accessible in the context of trauma, we tested the hypothesis that contextual information modulates how easily intrusions can be provoked by perceptual stimuli.. METHODS: Healthy participants viewed pictures depicting trauma scenes either with or without accompanying moderate (i.e. survival, recovery) or severe (i.e. fatality, permanent injury) outcome information. All participants viewed the same depictions of trauma scenes. Involuntary memories for the pictures were assessed using self-report diaries and an adapted version of the Impact of Event Scales (IES). A blurred picture perceptual priming paradigm was adapted to be used as an intrusion provocation task. RESULTS: The severe outcome group experienced a significantly higher frequency of intrusions on the intrusion provocation task in comparison to both moderate outcome and control (no-context) conditions. The severe outcome condition did not increase intrusions on the self-report diaries or the adapted IES. There was no effect of condition on ratings for the emotionality, self-relevance, valence, or seriousness of the trauma scenes. LIMITATIONS: The analogue method should not be generalized directly to incidences of real-life trauma. It was unclear why differences in intrusion frequency were found in the provocation task only. The relative amount of individual conceptual and data-driven processing adopted by the participants was not assessed. CONCLUSIONS: Manipulating contextual information that determines the meaning of sensory-perceptual features for a trauma scene can modulate subsequent intrusion frequency in response to visually similar cues.

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Displacement of the abdominal cuticle of the hermit crab, Pagurus pollicarus, activates motoneurons of the ventral superficial muscles that mediate posture and slow movements. Five excitatory motoneurons innervating the right ventral superficial muscle of the fourth abdominal segment were activated in a phasic stereotyped fashion in the isolated nervous system. Intracellular records from these motoneurons showed an initial monosynaptic burst, a period of inhibition in which inhibitory post-synaptic potentials were present and then a later period of increased spike frequency generated by excitatory post-synaptic potentials. The reflex response was maintained after severing all ganglionic roots from peripheral structures, isolating the nerve cord from peripheral feedback pathways. The two excitatory components of the response showed a dependence on strain that was much smaller than that found in sensory afferents. There was no relationship between the site of touch to the cuticle and the intensity or pattern of activation of the motoneurons. The reflex burst produced a transient activation of both longitudinal and transverse/circular layers of the muscle with forces that varied between 10% and 25% of the maximum muscle force. These results are consistent with a feedforward regulation of muscle stiffness.

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The heat-shock response in heat-tolerant variants (SB) and non-tolerant variants (NSB) of creeping bentgrass (Agrostis palustris Huds.) was investigated. Both variants were derived from callus initiated from a single seed of the cultivar Penncross. SB and NSB synthesized heat-shock proteins (HSPs) of 97, 83, 70, 40, 25, and 18 kD. There were no major differences between SB and NSB in the time or temperature required to induce the heat-shock response. When the HSPs synthesized by SB and NSB were analyzed by two-dimensional gel electrophoresis, it was apparent that SB synthesized two to three additional members of the HSP27 family, which were smaller (25 kD) and more basic than those synthesized by NSB. Analysis of F1 progeny of NSB x SB indicated that 7 of the 20 progeny did not synthesize the additional HSP25 polypeptides. These progeny were significantly less heat tolerant than progeny that did synthesize the additional HSP25 polypeptides. The X2 test of independence (X2 = 22.45, P < 0.001) indicated that heat tolerance and the presence of the additional HSP25 polypeptides are linked traits.