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.     

Examination of the MMPI-2 Restructured Clinical (RC) Scales in a Sample of Bariatric Surgery Candidates

The current study examined the MMPI-2 Restructured Clinical (RC) scales (Tellegen et al., MMPI-2 Restructured Clinical (RC) scales: Development, validation, and interpretation. Minneapolis: University of Minnesota Press, 2003) in a sample of 1,091 bariatric surgery candidates. The RC scales were developed to address concerns about limited discriminant validity of the Clinical scales. Internal consistency and external validity analyses were conducted to evaluate the RC scales in this setting. Results indicated that the RC scales are generally more internally consistent than the Clinical scales and display significantly better convergent and discriminant validity in predicting a variety of behavioral, psychological, and developmental variables relevant to preoperative bariatric psychological evaluations. Implications of the results and recommendations for future research with the RC scales in medical settings are discussed.     

Collaboration during visual search

Two experiments examine how collaboration influences visual search performance. Working with a partner or on their own, participants reported whether a target was present or absent in briefly presented search displays. We compared the search performance of individuals working together (collaborative pairs) with the pooled responses of the individuals working alone (nominal pairs). Collaborative pairs were less likely than nominal pairs to correctly detect a target and they were less likely to make false alarms. Signal detection analyses revealed that collaborative pairs were more sensitive to the presence of the target and had a more conservative response bias than the nominal pairs. This pattern was observed even when the presence of another individual was matched across pairs. The results are discussed in the context of task-sharing, social loafing and current theories of visual search.     

Eye-blink conditioning is associated with changes in synaptic ultrastructure in the rabbit interpositus nuclei

Eye-blink conditioning involves the pairing of a conditioned stimulus (usually a tone) to an unconditioned stimulus (air puff), and it is well established that an intact cerebellum and interpositus nucleus, in particular, are required for this form of classical conditioning. Changes in synaptic number or structure have long been proposed as a mechanism that may underlie learning and memory, but localizing these changes has been difficult. Thus, the current experiment took advantage of the large amount of research conducted on the neural circuitry that supports eye-blink conditioning by examining synaptic changes in the rabbit interpositus nucleus. Synaptic quantifications included total number of synapses per neuron, numbers of excitatory versus inhibitory synapses, synaptic curvature, synaptic perforations, and the maximum length of the synapses. No overall changes in synaptic number, shape, or perforations were observed. There was, however, a significant increase in the length of excitatory synapses in the conditioned animals. This increase in synaptic length was particularly evident in the concave-shaped synapses. These results, together with previous findings, begin to describe a sequence of synaptic change in the interpositus nuclei following eye-blink conditioning that would appear to begin with structural change and end with an increase in synaptic number.     

The effect of type and timing of feedback on learning from multiple-choice tests

Two experiments investigated how the type and timing of feedback influence learning from a multiple-choice test. First, participants read 12 prose passages, which covered various general knowledge topics (e.g., The Sun) and ranged between 280 and 300 words in length. Next, they took an initial six-alternative, multiple-choice test on information contained in the passages. Feedback was given immediately for some of the multiple-choice items or after delay for other items. Participants were either shown the correct answer as feedback (standard feedback) or were allowed to keep answering until the correct answer was discovered (answer-until-correct feedback). Learning from the test was assessed on a delayed cued-recall test. The results indicated that delayed feedback led to superior final test performance relative to immediate feedback. However, type of feedback did not matter: discovering the correct answer through answer-until-correct feedback produced equivalent performance relative to standard feedback. This research suggests that delaying the presentation of feedback after a test is beneficial to learning because of the spaced presentation of information.     

Attachment and the experience and expression of emotions in romantic relationships: a developmental perspective

In this longitudinal study, the authors tested a developmental hypothesis derived from attachment theory and recent empirical findings. Target participants were 78 individuals who have been studied intensively from infancy into their mid-20s. When targets were 20-23 years old, the authors tested the way in which interpersonal experiences at 3 pivotal points in each target's earlier social development--infancy/early childhood, early elementary school, and adolescence--predicted the pattern of positive versus negative emotions experienced with his or her romantic partner. A double-mediation model revealed that targets classified as securely attached at 12 months old were rated as more socially competent during early elementary school by their teachers. Targets' social competence, in turn, forecasted their having more secure relationships with close friends at age 16, which in turn predicted more positive daily emotional experiences in their adult romantic relationships (both self- and partner-reported) and less negative affect in conflict resolution and collaborative tasks with their romantic partners (rated by observers). These results are discussed in terms of attachment theory and how antecedent life experiences may indirectly shape events in current relationships.