Increased brain serotonin turnover in panic disorder patients in the absence of a panic attack: reduction by a selective serotonin reuptake inhibitor

Since the brain neurotransmitter changes characterising panic disorder remain uncertain, we quantified brain noradrenaline and serotonin turnover in patients with panic disorder, in the absence of a panic attack. Thirty-four untreated patients with panic disorder and 24 matched healthy volunteers were studied. A novel method utilising internal jugular venous sampling, with thermodilution measurement of jugular blood flow, was used to directly quantify brain monoamine turnover, by measuring the overflow of noradrenaline and serotonin metabolites from the brain. Radiographic depiction of brain venous sinuses allowed differential venous sampling from cortical and subcortical regions. The relation of brain serotonin turnover to serotonin transporter genotype and panic disorder severity were evaluated, and the influence of an SSRI drug, citalopram, on serotonin turnover investigated. Brain noradrenaline turnover in panic disorder patients was similar to that in healthy subjects. In contrast, brain serotonin turnover, estimated from jugular venous overflow of the metabolite, 5-hydroxyindole acetic acid, was increased approximately 4-fold in subcortical brain regions and in the cerebral cortex (P < 0.01). Serotonin turnover was highest in patients with the most severe disease, was unrelated to serotonin transporter genotype, and was reduced by citalopram (P < 0.01). Normal brain noradrenaline turnover in panic disorder patients argues against primary importance of the locus coeruleus in this condition. The marked increase in serotonin turnover, in the absence of a panic attack, possibly represents an important underlying neurotransmitter substrate for the disorder, although this point remains uncertain. Support for this interpretation comes from the direct relationship which existed between serotonin turnover and illness severity, and the finding that SSRI administration reduced serotonin turnover. Serotonin transporter genotyping suggested that increased whole brain serotonin turnover most likely derived not from impaired serotonin reuptake, but from increased firing in serotonergic midbrain raphe neurons projecting to both subcortical brain regions and the cerebral cortex.     

Psychotropic placebos create resistance to the misinformation effect

Can a placebo for a psychotropic drug help participants resist the misinformation effect? To answer this question, we gave participants a mixture of baking soda and water and told half of them that the mixture was a cognition-enhancing drug called R273 and told the other half that it was an inactive version of the drug. Shortly thereafter, all participants took part in a three-stage misinformation experiment. Compared with participants who were told that they had taken the placebo, the participants who were told that they had taken the drug reported improved cognitive abilities and were less susceptible to the misinformation effect. We provide sourcemonitoring and mindfulness accounts of our findings.     

Consumer sophistication and the role of emotion on satisfaction judgments within credence services

• Evidence which demonstrates a link between the affective dimension and satisfaction in a tangible product based context is well documented. However, when placed in a credence service context the role of Affect becomes more complex. Previous research in this field has assumed consumer homogeneity when there is increasing evidence of consumer heterogeneity. This research attempts to address this by examining affective reactions to service encounters between two groups of respondents, one with the ability to make performance assessments about the service and one without. Findings suggest consumers of differing sophistication will vary in the way they form expectation and performance assessments about the technical, functional and affective components of credence services and that consumer sophistication may have a moderating influence on affective reactions evoked. This in turn has implications for the design and delivery of service offerings within such contexts.

Copyright © 2007 John Wiley & Sons, Ltd.     

Rapid reacquisition of fear to a completely extinguished context is replaced by transient impairment with additional extinction training

A series of experiments studied reacquisition of fear reactions to a completely extinguished context. Reacquisition was rapid when reconditioning occurred as soon as the fear reactions were completely extinguished, showing that the original conditioning was intact. However, when reconditioning occurred after massive extinction training, fear reactions were depressed but then recovered across a long retention interval. This recovery was due to reconditioning and was similar to that produced by conditioning a massively preexposed context. These results show that massive extinction converts a potentially dangerous context into one that is merely familiar.     

Cognitive style and learning: performance of adaptors and innovators in a novel dynamic task

The influence of cognitive style on performance in a novel dynamic task modelled on the task of controlling air traffic was investigated. It was hypothesized that participants who preferred a more adaptive cognitive style would maintain better rule adherence and safe distances between aircraft in a low‐fidelity air traffic control task than those who preferred a more innovative style. Problems were presented to participants using computer‐based scenarios in screening, practice, and experimental trials. Performance was measured by the number of times the participant violated two types of scenario rules. Screening, practice, and experimental performance were analysed separately. Cognitive style had a significant effect on performance only during experimental trials. Performance of individuals who preferred a more adaptive style improved across experimental trials while those preferring a more innovative style did not. Results suggest that the more innovative participants, although perhaps having some initial advantage, may not be able to sustain performance in this type of task. Published in 2001 by John Wiley & Sons, Ltd.     

On the Strategic Weighting of Spectral Information in Consonant Identification

When identifying speech sounds, do listeners direct attention specifically to those frequency regions in which distinctive phonetic information is located? Scharf, Dai, and Miller (1988) concluded that they do, based on an experiment that involved listeners identifying the members of a pair of voiced stop consonants differing primarily in their third-formant transitions. Adding extra contrastive acoustic energy to the third-formant region of one of the consonants enhanced performance more than did adding energy to a region where the consonants were otherwise identical. The present experiments extended this paradigm to reveal evidence of an interaction between the frequency region in which extra distinctive energy was added and the class of consonant to which it was added. The results were more consistent with an account in terms of the effects of added energy on phonetic identity than one based on spectral selective attention.