Transient activation of the CA3 Kappa opioid system in the dorsal hippocampus modulates complex memory processing in mice

The hippocampus plays a central role in various forms of complex learning and memory. Opioid peptides and receptors are abundant in the hippocampus. These peptides are co-released with glutamate from mossy fiber- and lateral perforant path-synapses. In this study, we evaluated the functional relevance of the CA3 Kappa opioid receptors (KOR) by transient pharmacological activation or inactivation using single bilateral intrahippocampal microinjections of a selective agonist (U50,488H, 1 or 2.5 nmol), a selective antagonist (nor-binaltorphimine, norBNI 5 nmol) or a mixture of both. C57Bl/6J mice were tested in a fear conditioning paradigm (FC) or in a modified version of the water maze task thought to reveal how flexibly animals can learn and manipulate spatial information (WM). In FC, the agonist (2.5 nmol) decreased context-induced (but not tone-induced) freezing whereas norBNI had no effect. The impairment caused by the agonist U50,488H was blocked by the injection of norBNI, suggesting that overstimulation of CA3-KOR impairs the acquisition and consolidation of contextual fear-related memory. In the WM task, mice were trained repeatedly each day to find a hidden platform. After having reached this goal, the platform position was changed the next day for a new task. U50,488H injection before the last task abolished the previously acquired ability to find rapidly a new platform location, whereas adding norBNI reversed this impairment. Thus, in the mouse, even partial and topographically restricted activation of CA3-KOR entails impairments in two different hippocampus-dependent tasks, indicating functional relevance of the kappa opioid system.     

The effects of mindfulness on executive processes and autobiographical memory specificity

Previous studies have found that mindfulness training reduces overgeneral memories and increases autobiographical memory specificity (e.g., [Williams, J. M. G., Teasdale, J. D., Segal, Z. V., & Soulsby, J. (2000). Mindfulness-based cognitive therapy reduces overgeneral autobiographical memory in formerly depressed patients. Journal of Abnormal Psychology, 109, 150-155]). However, little work has investigated the mechanisms underlying this effect. The present study explored the role of executive processes as a mediator of MBCT effects in an unselected sample. An autobiographical memory task, a cognitive inhibition task, a motor inhibition task, a cognitive flexibility task and a motor flexibility task were administered before and after intervention. Compared to matched controls, MBCT participants showed increased autobiographical memory specificity, decreased overgenerality, and improved cognitive flexibility capacity and capacity to inhibit cognitive prepotent responses. Mediational analyses indicated that changes in cognitive flexibility partially mediate the impact of MBCT on overgeneral memories. Results are discussed in terms of Conway's [2005. Memory and the self. Journal of Memory and Language, 53, 594-628] autobiographical memory model.     

Eating Disorders Inventory: Assessment of its Construct Validity in a Nonclinical French Sample of Adolescents

Recent studies have questioned the appropriateness of the original Eating Disorders Inventory (EDI) in nonclinical samples of adolescents. The main objective of the present series of studies is to systematically test the construct validity of the EDI (i.e. content, factorial, convergent, discriminant and discriminative) in a nonclinical sample of French adolescents. A total sample of 1,323 adolescents was involved in these five studies. The factorial validity and the measurement invariance of the EDI were verified through confirmatory factorial analyses. Correlation and student t-tests were also used to test the convergent and discriminative validity of the EDI. Results from the first study confirmed the unsuitability of the French original EDI for young adolescents. Items were re-worded and an adaptation for adolescents was developed (EDI-A). The following four studies provided support for the factorial validity, measurement invariance, reliability, convergent validity and discriminant validity for a short form (i.e. 24 items) of the EDI-A. The present results thus provide preliminary evidence regarding the construct validity of the 24-item EDI-A for French nonclinical adolescents. Recommendations for future uses and research activities with this instrument in French speaking adolescents are outlined.     

Putting the pieces together: reviewing the structural conceptualization of motivation within SDT

Motivation and Emotion - Self-determination theory presents a multi-dimensional approach to human motivation in which motivation is driven by a range of classifiably distinct regulation styles....     

Mental stress on children exposed to war and natural catastrophes

This paper calls attention to the plight of children exposed to various traumas associated with wars and other natural disasters around the world. Little systematic attention has been paid to the mental health needs of child survivors of armed conflict. Our observations and experiences around the world would suggest that there are significant differences in the degree to which children have been prepared in anticipation of exposure to violence and in interventions applied after their exposure. It is the authors' impression that prevention and intervention can be quite powerful when employed in these situations.     

The effects of conformity on recognition judgements for emotional stimuli

Exposure to another’s account of a shared event can influence the content of an individual’s memory report. We examine whether the emotionality of the to-be-remembered information influences the likelihood that socially encountered post-event information is accepted into memory. Participants were exposed to positive, negative or neutral emotional pictures. Subsequently, they had to discriminate these pictures from new pictures in a ‘yes/no’ recognition decision either before or subsequent to a confederate providing misinformation, accurate or no information. Post-event information influenced participants’ responding in the recognition test. Effects were larger for participants viewing neutral items and persisted for these items on a subsequent private source monitoring test. These findings indicate that people rely more on information from others when encountering non-emotional compared to emotional items. We suggest that increased memory strength in conjunction with access to strong retrieval cues in the recognition test serves to shield emotional items from vulnerability to effects of memory conformity.     

Response timing and development: Fixed-interval performance in precociously weaned rats

Young rats weaned at 16 days were taught to press a lever by shaping at 18 days and trained for 11 days (from 20 to 30 days of age) on a fixed-interval 60-sec schedule, at a rate of 5 half-hour sessions per day. Comparison with rats weaned at 16 or 20 days, trained at 21 days, and subjected for 8 days (from 23 to 30 days of age) to the same procedure showed that the temporal regulation of behaviour, as evaluated by the Curvature Index, was mostly training-dependent. Post-reinforcement pause durations depended upon the mixed influence of age and training. The evolution of running rates mostly depended upon training, whereas trends in overall rates seemed to depend essentially upon the age of the subjects. Precocious weaning per se or raising conditions prior to weaning did not significantly influence the temporal regulation of behaviour under FI. The results support previous ideas that overall response rate and response timing were dissociated and indicate high sensitivity to periodic stimuli in weanling rats. Finally, they show that, within an information processing model of timing, FI data of weanling rats might be compatible with their having an “internal clock” that runs at a higher rate than in older subjects.     

When Legitimizing a Request Increases Compliance: The Legitimizing Object Technique

Earlier research reported that using pictures in a fundraising request increases donations by legitimizing the solicitation. The present study tested the effectiveness of a solicitation for money made in the street when an object that legitimated the request was present or not. Male confederates asked passersby for money to buy a stamp while either holding or not holding an envelope in one hand. With a high effect-size, it was reported that the presence of the envelope increased compliance with the request. The legitimation of the request associated with the presence of the envelope is used to explain the results.     

Closed-loop bird–computer interactions: a new method to study the role of bird calls

In the field of songbird research, many studies have shown the role of male songs in territorial defense and courtship. Calling, another important acoustic communication signal, has received much less attention, however, because calls are assumed to contain less information about the emitter than songs do. Birdcall repertoire is diverse, and the role of calls has been found to be significant in the area of social interaction, for example, in pair, family, and group cohesion. However, standard methods for studying calls do not allow precise and systematic study of their role in communication. We propose herein a new method to study bird vocal interaction. A closed-loop computer system interacts with canaries, Serinus canaria, by (1) automatically classifying two basic types of canary vocalization, single versus repeated calls, as they are produced by the subject, and (2) responding with a preprogrammed call type recorded from another bird. This computerized animal–machine interaction requires no human interference. We show first that the birds do engage in sustained interactions with the system, by studying the rate of single and repeated calls for various programmed protocols. We then show that female canaries differentially use single and repeated calls. First, they produce significantly more single than repeated calls, and second, the rate of single calls is associated with the context in which they interact, whereas repeated calls are context independent. This experiment is the first illustration of how closed-loop bird–computer interaction can be used productively to study social relationships.