Corticosterone effects on BDNF mRNA expression in the rat hippocampus during morris water maze training

Corticosterone and Brain-Derived Neurotrophic Factor (BDNF) have both been shown to be involved in spatial memory formation in rats. In the present study we have investigated the effect of corticosterone on hippocampal BDNF mRNA expression after training in the Morris water maze in young adult Wistar rats. Therefore, we first studied BDNF mRNA levels in the hippocampus in relation to corticosterone levels at several time points after 4 training trials in the Morris water maze. Corticosterone levels were significantly increased after this procedure, and hippocampal BDNF mRNA levels only displayed a minor change: an increase in CA1 at 1 hr after training. However, in a previous study we observed dramatically decreased hippocampal BDNF mRNA levels in dentate gyrus and CA1 at 3 hr after injection of corticosterone. In order to analyze this discrepancy, we subsequently investigated if hippocampal BDNF mRNA expression is affected by corticosterone at 3 hr after water maze training. Therefore, we incorporated ADX animals and ADX animals which were injected with corticosterone in our study. ADX animals which were subjected to water maze training displayed similar hippocampal BDNF mRNA levels 3 hr after training compared to control ADX animals. Furthermore, ADX animals which were injected with corticosterone showed decreased BDNF mRNA levels in all hippocampal regions compared to control ADX animals. Water maze training did not alter this effect. Thus, the increased corticosterone levels during water maze training do not affect hippocampal BDNF mRNA expression, although exogenous corticosterone is effective under these conditions. Hence, our results suggest that in this situation BDNF is resistant to regulation by endogenous corticosterone, which may be important for learning and memory processes.     

Influences of Parental and Best Friends' Smoking and Drinking on Adolescent Use: A Longitudinal Study1

Many studies have dealt with the relative impact of parents and peers on adolescent substance use. However, only a few studies have explored the role of adolescents themselves in social relationships. Homogeneity in behavioral patterns within friendships can also be generated by selective association. Acknowledgment of selection processes might shed new light on the debate on the influences of parents and friends. This paper examines the impact of parental and best friends' smoking and drinking on adolescents' use, using data (N= 1,063) from a 3-wave, 5-year longitudinal study. The results show that friends' smoking did not affect adolescent smoking over time. Only in early adolescence did friends' drinking exert an influence on subjects' alcohol use. On the other hand, parental use had a small but significant impact on their offspring. Furthermore, support was found for processes of selective association.     

Simple mental addition in children with and without mild mental retardation.

The speeded performance on simple mental addition problems of 6- and 7-year-old children with and without mild mental retardation is modeled from a person perspective and an item perspective. On the person side, it was found that a single cognitive dimension spanned the performance differences between the two ability groups. However, a discontinuity, or "jump," was observed in the performance of the normal ability group on the easier items. On the item side, the addition problems were almost perfectly ordered in difficulty according to their problem size. Differences in difficulty were explained by factors related to the difficulty of executing nonretrieval strategies. All findings were interpreted within the framework of Siegler's (e.g., R. S. Siegler & C. Shipley, 1995) model of children's strategy choices in arithmetic. Models from item response theory were used to test the hypotheses.     

Collective self-esteem, personal self-esteem, and collective efficacy in in-group and outgroup evaluations

In assessing the relationship between self-esteem and in-group/outgroup evaluations, this study examined whether self-esteem is better measured at a collective (collective self-esteem [CSE]) than a personal level (personal self-esteem [PSE]). It was expected that subjects high in CSE would engage in more in-group favoritism (measured by in-group evaluations), whereas those low in CSE would engage in more outgroup derogation (measured by outgroup evaluations). No effect for PSE was predicted. Furthermore, the study explored whether perceptions of collective efficacy may underlie this relationship. Subjects played a public goods task. The in-group's outcome was compared to the outcome of other relevant outgroups, enhancing pressures towards intergroup differentiation. Consistent with the predictions, subjects high in CSE evaluated in-group members more positively than those in low CSE (i.e., in-group favoritism), whereas subjects low in CSE evaluated outgroup members more negatively than those high in CSE (i.e., outgroup derogation). Also in line with our predictions, no effect for PSE was found. Perceptions of collective efficacy appeared to be a mediator of the effect of CSE.     

The Props are Falling Down and We Want to Make Music: A Narrative Perspective on Organisations in Transition (Violins/Violence in Organisations)

While South African society finds itself in the throes of political changes, therapists working within organisations in transition find themselves challenged by the turbulence of transformation. The authors are a group of therapists attempting to understand, from a narrative perspective, the organisational context within which they work. This paper recounts the processes around the design, implementation, and outcomes of a workshop on this theme. The main body of the paper consists of a letter that was sent to participants after the workshop. The reader is invited to join collaboratively in our reflections so as to continue an open-ended, creative process.     

The contribution of working memory resources in the verification of simple mental arithmetic sums

The present study replicated the investigations of Lemaire, Abdi, and Fayol with some modifications: the random time interval generation (RIG) task was used and the stimuli were created in another way. The results provide additional evidence for the crucial role of the central executive in the speed of solving both true and false sums and for the role of the phonological loop in solving false sums. However, the findings concerning the role of this slave system in solving true sums were different. Possible explanations and limitations of these results are discussed. Received: 16 April 1998 / Accepted: 20 July 1998     

Coping Strategies and Locus of Control as Mediating Variables in the Relation Between Exposure to Political Life Events and Psychological Adjustment in Israeli Children

The relation between political life events and distress was examined with particular emphasis on coping strategies and locus of control as two possible mediators. Subjects were 88 Israeli children. Results partially supported a linear relation between reported impact of exposure and distress. Findings for coping strategies as a mediator suggested, counterintuitively, that greater use of coping strategies is related to more experienced distress. Findings for locus of control as a mediator suggested that subjects with external locus of control experience greater distress, other than in the case of depressive symptomatology. These results indicate that coping strategies and locus of control play a complex role in the stress-outcome relation, the precise nature of which remains to be resolved. Theoretical, clinical and political implications of the findings are discussed.     

The intermodal representation of speech in newborns

It has been proposed that speech is specified by the eye, the ear, and even the skin. Kuhl and Meltzoff (1984) showed that 4-month-olds could lip-read to an extent. Given the age of the infants, it was not clear whether this was a learned skill or a by-product of the primary auditory process. This paper presents evidence that neonate infants (less than 33 h) show virtually identical patterns of intermodal interaction as do 4-month-olds. Since they are neonates, it is unlikely that learning was involved. The results indicate that human speech is specified by both eye and ear at an age when built-in structural sensitivities provide the most plausible explanation.     

An inexpensive system for measuring the processing of relational information by romantic partners

The present paper describes the computer aspects of a reaction time experiment with couples. The hardware consists of two computers connected through a local area network. Issues that deal with the first PC include timing routines, screen control, mice data decoding, and synchronization of computer software—written in Assembler for a PC without hard disk—with information presented in a videotape. The second computer was used for data processing that was written in VBA. Although the system was created for a dedicated purpose, it is easily applicable to other environments.     

Burgeoning skepticism

This paper shows that the resources mobilized by recent arguments against individualism in the philosophy of mind also suffice to construct a good argument against a Humean-style skepticism about our knowledge of extra-mental reality. The argument constructed, however, will not suffice to lay to rest the attacks of a truly global skeptic who rejects the idea that we usually know what our occurrent mental states are.