Knockdown of Nurr1 in the rat hippocampus: implications to spatial discrimination learning and memory

Nurr1 expression is up-regulated in the brain following associative learning experiences, but its relevance to cognitive processes remains unclear. In these studies, rats initially received bilateral hippocampal infusions of control or antisense oligodeoxynucleotides (ODNs) 1 h prior to training in a holeboard spatial discrimination task. Such pre-training infusions of nurr1 antisense ODNs caused a moderate effect in learning the task and also impaired LTM tested 7 d later. In a second experiment, ODN infusions were given immediately after the animals had received two sessions of training, during which all animals showed normal learning. Although antisense treated rats were significantly impaired during the post-infusion stages of acquisition of the task, no group differences were observed during the LTM test given 7 d later. These animals were subjected 3 d later to reversal training in the same maze in the absence of any additional treatments. Remarkably, rats previously treated with antisense ODNs displayed perseveration: The animals were fixated with the previously learned pattern of baited holes, causing them to be significantly impaired in the extinction of acquired spatial preferences and future learning. We postulate that Nurr1 function in the hippocampus is important for normal cognitive processes.     

Blinks of the mind: memory effects of attentional processes

If 2 words are presented successively within 500 ms, subjects often miss the 2nd word. This attentional blink reflects a limited capacity to attend to incoming information. Memory effects were studied for words that fell within an attentional blink. Unrelated words were presented in a modified rapid serial visual presentation task at varying stimulus-onset asynchronies, and attention was systematically manipulated. Subsequently, recognition, repetition priming, and semantic priming were measured separately in 3 experiments. Unidentified words showed no recognition and no repetition priming. However, blinked (i.e., unidentified) words did produce semantic priming in related words. When, for instance, ring was blinked, it was easier to subsequently identify wedding than apple. In contrast, when the blinked word itself was presented again, it was not easier to identify than an unrelated word. Possible interpretations of this paradoxical finding are discussed.     

The stress and coping questionnaire for children (school version and asthma version): construction,factor structure,and psychometric properties

Based on Lazarus and Folkman's 1984 Stress-Coping Model, a self-report measure for children between 8 and 12 years of age was constructed. It is called the Stress and Coping Questionnaire for Children (School version and Asthma version) and measures children's emotional responses and coping strategies when they confront school-related and asthma-related stressors. The factor structure of this questionnaire was assessed and cross-validated in two samples, one of 392 primary school children without a chronic disease and one of 119 children with asthma. Five scales of coping strategies with regard to two school-related stressors and one asthma-related stressor were distinguished in a reliable way, Approach, Avoidance, Seeking Social Support, Aggression, and Crying.     

Correlates of suicide in the older adult population in Quebec

This study was undertaken to describe the characteristics of adults aged 60 years and over who committed suicide in Quebec in 1998-1999. In this study, 42.6% of the suicide cases presented mental disorders at the time of their death, mainly depression. Sixty-five (65.3%) percent of the suicide cases would have been considered as having a mental health disorder if sub-threshold depression cases were included. Only 27.7% of the cases did not express any idea of death during the 6-month period preceding their suicide. One interesting finding was that 53.5% of the suicide cases consulted a general practitioner or specialist during the 2-week period preceding their death. Our results showed that only 8.1% had a severe level of functional limitations at the time of their death. This result leads us to interpret with caution the conclusion of some studies suggesting that physical frailty is a major causal factor associated with suicide among the elderly.     

Evidence for a gene-environment interaction in predicting behavioral inhibition in middle childhood

Gene-environment interactions are presumed to shape human behavior during early development. However, no human research has demonstrated that such interactions lead to stable individual differences in fear responses. We tested this possibility by focusing on a polymorphism in the promoter region of the gene for the serotonin transporter (5-HTT). This polymorphism has been linked to many indices of serotonin activity. Specifically, we tested the hypothesis that an interaction between children's 5-HTT status and maternal reports of social support predicts inhibited behavior with unfamiliar peers in middle childhood. Results were consistent with this hypothesis: Children with the combination of the short 5-HTT allele and low social support had increased risk for behavioral inhibition in middle childhood.     

Temporal references in dreams and autobiographical memory

In an attempt to determine whether temporal references identified in dreams follow the same temporal distributions as those documented for autobiographical memories, 28 younger women (18-35 years of age) and 30 older women (60-77 years of age) kept a home dream diary for 1 week and then slept 1 night in the laboratory for rapid eye movement sleep dream collection. The following morning, they identified temporal references in their dreams and produced a sample of autobiographical memories using the semantic cuing method. For both groups, there was a linear decrease in temporal references identified in dreams and autobiographical memories with increased remoteness for the last 30 years. As predicted, for the older group, there were similar cubic trends reflecting a disproportionately higher number of both temporal references identified in dreams and autobiographical memories from adolescence/early adulthood compared with adulthood and childhood. The results support the notion of continuity between waking and dreaming memory processes.     

Are twins different from singletons during early childhood?

This paper examines the specificity of intrafamilial experiences to which twins are exposed during early childhood, and the impact of this family context on the psychological development of twins. An overview of the literature on the psychological development of twins indicates two broad categories of findings. The first category covers studies dealing with the developmental features that appear early in twins. Although there are numerous studies comparing the psychomotor and verbal development of twins to singletons, only a few have dealt with the emergence of personality and identity, and most have been conducted in clinical settings. The second set of studies deals with mother-twin relations, explored in recent years in terms of the psychosocial stress created by twin births. Few studies have examined the mother-twin relationship in the light of major theories on mother-child bonding (psychoanalysis, attachment, interactionist model). These developmental models have mainly focused on mother-infant dyads, while the construction of this specific mother-twin relationship needs to be set within the framework of a triadic situation. Rather than describing a specific ‘twin mentality’, it is argued here that the twin situation should be seen as a special case of adaptative development, both for the mother and the child, which has effects on the formation of the individual.     

The Potential Mediating Role of Parenting Practices in the Development of Conduct Problems in a Clinic-Referred Sample

Research has consistently found associations among parenting practices, socioeconomic disadvantage, ethnicity and conduct problems in children. We investigated whether parenting practices might mediate the relation between ethnicity and conduct problems and the relation between socioeconomic status (SES) and conduct problems. The subjects were 141 clinic-referred children between the ages of 6 and 17 and their primary custodial parents. Using multiple indicators for each construct, except ethnicity, the mediational role of parenting was tested using structural equation modeling. The results indicated that the effects of SES on conduct problems was largely mediated by the influence of ineffective parenting practices. In contrast, ethnicity was not associated with conduct problems in this clinic-referred sample, even prior to controlling for SES and parenting practices, suggesting that the link between minority status and conduct problems may be dependent on the demographic characteristics of the sample. Exploratory analyses also revealed that there were ethnic differences in the types of parenting practices that were most strongly associated with conduct problems.     

The effect of a textured visual field on modality dominance in a ventriloquism situation

Despite the often encountered affirmation that vision completely dominates other modalities in intersensory conflict, there are cases where discordant auditorv information affects the localization of a visual signal. Experiment I shows that “auditory capture” occurs with a visual input reduced to a single luminous point in complete darkness, but not with a textured background. The task was to point at a flashing luminous point alternately in the presence of a synchronous sound coming from a source situated 15° to one side (“conflict trials,” designed to measure immediate reaction to conflict) and in its absence (“test trials,” to measure aftereffects). Adaptive immédiate reactions and aftereffects were observed in the dark, but not with a textured background. In Experiment II, on the other hand, “visual capture” of auditory localization was observed at the levels of both measures in the dark and with the textured background. That visual texture affects the degree of auditory capture of vision, but not the degree of visual capture of audition was confirmed at the level of aftereffects in Experiment III, where bisensory monitoring was substituted for pointing during exposure to conflict. The empirical finding eliminates apparent contradictions in the literature on ventriloquism, but cannot itself be explained in terms either of relative accuracy of visual and auditory localization or attentional adjustments.