Preservation of long-term memory and synaptic plasticity despite short-term impairments in the Tc1 mouse model of Down syndrome

Down syndrome (DS) is a genetic disorder arising from the presence of a third copy of the human chromosome 21 (Hsa21). Recently, O’Doherty and colleagues in an earlier study generated a new genetic mouse model of DS (Tc1) that carries an almost complete Hsa21. Since DS is the most common genetic cause of mental retardation, we have undertaken a detailed analysis of cognitive function and synaptic plasticity in Tc1 mice. Here we show that Tc1 mice have impaired spatial working memory (WM) but spared long-term spatial reference memory (RM) in the Morris watermaze. Similarly, Tc1 mice are selectively impaired in short-term memory (STM) but have intact long-term memory (LTM) in the novel object recognition task. The pattern of impaired STM and normal LTM is paralleled by a corresponding phenotype in long-term potentiation (LTP). Freely-moving Tc1 mice exhibit reduced LTP 1 h after induction but normal maintenance over days in the dentate gyrus of the hippocampal formation. Biochemical analysis revealed a reduction in membrane surface expression of the AMPAR (α-amino-3-hydroxy-5-methyl-4-propionic acid receptor) subunit GluR1 in the hippocampus of Tc1 mice, suggesting a potential mechanism for the impairment in early LTP. Our observations also provide further evidence that STM and LTM for hippocampus-dependent tasks are subserved by parallel processing streams.     

The Journal of the Experimental Analysis of Behavior at fifty

The Journal of the Experimental Analysis of Behavior was founded in 1958 by a group of male psychologists, mainly from the northeastern USA and connected with either Harvard or Columbia. Fifty years later about 20% of both editors and authors reside outside this country and almost the same proportion is made up of women. Other changes in the journal include having its own website for more than a decade and now publishing online as well as on paper. A recent connection with PubMed Central of the National Library of Medicine has made possible the completely free electronic presentation of the entire archive of about 3,800 articles.     

Structural priming: a critical review

Repetition is a central phenomenon of behavior, and researchers have made extensive use of it to illuminate psychological functioning. In the language sciences, a ubiquitous form of such repetition is structural priming, a tendency to repeat or better process a current sentence because of its structural similarity to a previously experienced ("prime") sentence (J. K. Bock, 1986). The recent explosion of research in structural priming has made it the dominant means of investigating the processes involved in the production (and increasingly, comprehension) of complex expressions such as sentences. This review considers its implications for the representation of syntax and the mechanisms of production and comprehension and their relationship. It then addresses the potential functions of structural priming, before turning to its implications for first language acquisition, bilingualism, and aphasia. The authors close with theoretical and empirical recommendations for future investigations.     

Thinking of Others: Feminist Identification and the Perception of Others’ Beliefs

Previous research has shown that most women in the United States support feminist goals but do not label themselves as feminists. Concern over other people’s opinions of feminists may predict rejection of the feminist label. In the present study we predicted that feminists would be more likely than non-feminists to believe that other people view feminists favorably. One hundred seventy-one female participants completed the Berryman-Fink Semantic Differential Scale twice, once to indicate how they view feminists and again to indicate how they believe others view feminists. Contrary to our hypothesis, all women, regardless of feminist identification, believed that others view feminists negatively and as more likely to be homosexual than heterosexual. Relationships between participants’ own views of feminists and their perceptions of others’ views of feminists were explored. Transformative experiences that may lead a feminist to ignore their perception of society’s views are discussed.     

The effects of preparedness for suicide following the death of a young adult child

Suicide deaths are often viewed as sudden and unexpected. Research examining bereavement responses to suicide are generally set within this conceptual framework. Twenty-two parents were interviewed about their bereavement experience following the suicide death of a young adult son or daughter. Data analyzed using narrative methods revealed the concept of preparedness. Three distinct preparedness narratives were identified, termed turbulent-relief, tragedy, and reflective plots. The data presented here highlights the way in which these different situations influence the resultant grief. Understanding preparedness for suicide assists in explaining the variety of grief responses in parents bereaved in this manner.     

The psychosocial impact of Hurricane Katrina: contextual differences in psychological symptoms, social support, and discrimination

This study tested a contextual model of disaster reaction by examining regional differences in the psychosocial impact of Hurricane Katrina. A total of 386 individuals participated in this study. All were recruited in the primary areas affected by Hurricane Katrina and included residents of metropolitan New Orleans (Orleans Parish, Louisiana), Greater New Orleans (i.e., Metairie, Kenner, Gretna), and the Mississippi Gulf Coast (i.e., cities along the coast from Waveland to Ocean Springs, Mississippi). Participants were assessed for posttraumatic stress disorder (PTSD) symptoms, other psychological symptoms, perceptions of discrimination, perceptions of social support, evacuation distance, and the extent to which they experienced hurricane-related stressful events. Results were consistent with previous research on the impact of disasters on mental health symptoms. Findings extended research on individual differences in the response to trauma and indicated that regional context predicted unique variance in the experience of discrimination, social support, and emotional symptoms consistent with the theoretical model presented.     

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.     

Reconsolidation of declarative memory in humans

The reconsolidation hypothesis states that a consolidated memory could again become unstable and susceptible to facilitation or impairment for a discrete period of time after a reminder presentation. The phenomenon has been demonstrated in very diverse species and types of memory, including the human procedural memory of a motor skill task but not the human declarative one. Here we provide evidence for both consolidation and reconsolidation in a paired-associate learning (i.e., learning an association between a cue syllable and the respective response syllable). Subjects were given two training sessions with a 24-h interval on distinct verbal material, and afterward, they received at testing two successive retrievals corresponding to the first and second learning, respectively. Two main results are noted. First, the first acquired memory was impaired when a reminder was presented 5 min before the second training (reconsolidation), and also when the second training was given 5 min instead of 24 h after the first one (consolidation). Second, the first retrieval proved to influence negatively on the later one (the retrieval-induced forgetting [RIF] effect), and we used the absence of this RIF effect as a very indicator of the target memory impairment. We consider the demonstration of reconsolidation in human declarative memory as backing the universality of this phenomenon and having potential clinical relevance. On the other hand, we discuss the possibility of using the human declarative memory as a model to address several key topics of the reconsolidation hypothesis.     

Influence of impulsivity-reflexivity when testing dynamic spatial ability: sex and g differences

This work analyzes the possibility that the differences in the performance of men and women in dynamic spatial tasks such as the Spatial Orientation Dynamic Test-Revised (SODT-R; Santacreu & Rubio, 1998), obtained in previous works, are due to cognitive style (Reflexivity-Impulsivity) or to the speed-accuracy tradeoff (SATO) that the participants implement. If these differences are due to cognitive style, they would be independent of intelligence, whereas if they are due to SATO, they may be associated with intelligence. In this work, 1652 participants, 984 men and 668 women, ages between 18 and 55 years, were assessed. In addition to the SODT-R, the "Test de Razonamiento Analitico, Secuencial e Inductivo" (TRASI [Analytical, Sequential, and Inductive Reasoning Test]; Rubio & Santacreu, 2003) was administered as a measure of general intelligence. Impulsivity scores (Zi) of Salkind and Wright (1977) were used to analyze reflexivity-impulsivity and SATO. The results obtained indicate that (a) four performance groups can be identified: Fast-accurate, Slow-inaccurate, Impulsive, and Reflexive. The first two groups solve the task as a function of a competence variable and the last two as a function of a personality variable; (b) performance differences should be attributed to SATO; (c) SATO differs depending on sex and intelligence level.