Working memory deficits in retinoid X receptor gamma-deficient mice

Retinoid signaling has been recently shown to be required for mnemonic functions in rodents. To dissect the behavioral and molecular mechanisms involved in this requirement, we have analyzed the spatial and recognition working memory in mice carrying null mutations of retinoid receptors RARbeta and RXRgamma. Double mutants appeared deficient in spatial working memory as tested in spontaneous alternation in the Y-maze and delayed nonmatch to place (DNMTP) test in the T-maze. These mutant mice did acquire, however, spatial place reference or right/left discrimination tasks in the T-maze set-up, indicating that basic sensorimotor functions, spatial orientation, and motivational factors are unlikely to account for deficits in working memory-sensitive tasks. Double-mutant mice were also deficient in novel object recognition at intermediate, but not short delays. RXRgamma appeared to be the functionally predominant receptor in modulation of the working memory, as RXRgamma, but not RARbeta single null mutant mice exhibited deficits similar to those observed in the double mutants. The mechanism of this modulation is potentially related to functions of RXRgamma in frontal and perirhinal cortex, structures in which we detected RXRgamma expression and which are functionally implicated in working memory processes.     

What makes working memory spans so predictive of high-level cognition?

Working memory (WM) span tasks involving a complex activity performed concurrently with item retention have proven to be good predictors of high-level cognitive performance. The present study demonstrates that replacing these complex self-paced activities with simpler but computer-paced processes, such as reading successive letters, yields more predictive WM span measures. This finding suggests that strategic factors do not contribute to be relationship between WM spans and high-level cognition.     

Examining African self-consciousness and Black racial identity as predictors of Black men's psychological well-being

This study investigated African self-consciousness and Black racial identity as predictors of psychological distress and self-esteem for Black men. One hundred thirty Black men from a college and community sample completed the African Self-Consciousness Scale, the Racial Identity Attitude Scale-B, the Symptom Checklist 90-Revised, and the Coopersmith Self-Esteem Inventory. Canonical correlation analysis found 2 significant roots with the 1st root indicating that Black men whose attitudes reflected Preencounter and Immersion racial identity attitudes and who do not resist against anti-African/Black forces reported greater psychological distress and less esteem. Results from the 2nd root suggested that Black men whose attitudes reflect greater Internalization racial identity attitudes, greater resistance to anti-African/Black forces, and less identification with Blacks reported greater self-esteem.     

Symbolic distance affects two processing loci in the number comparison task

A dual-task procedure was used to investigate the attentional requirements of number processing. The results show that (1) numeric information in Task 2 can be retrieved in parallel with capacity-demanding processing in Task 1 but (2) comparing two quantities requires central capacity, which is depleted by switching from one task to another. This finding resolves an apparent discrepancy in the literature, in which digit magnitude information has not been retrieved in parallel with a second task (Logan & Schulkind, 2000), despite repeated demonstrations that this information is retrieved autonomously, even when it is deleterious to performance (Henik & Tzelgov, 1982). A model is proposed to reconcile existing findings with the new ones revealed in the present investigation.     

Cognitive discernible factors between schizophrenia and schizoaffective disorder

BACKGROUND: Schizophrenia (SZ) and schizoaffective disorders (SA) are associated with cognitive deficits. Generally, a schizoaffective diagnosis is associated with better prognosis on the level of social integration. It is also well established that cognition is an important factor for good social outcome in schizophrenia. We hypothesized that, although patients suffering from SA share symptoms with SZ, they can be differentiated on the basis of neurocognitive function and that SA perform better in several domains. METHOD: Performances of two groups SA (N = 13) and SZ (N = 44) were compared on several visual-motor tasks using CANTAB [Motor Screening (MOT), Reaction Time (RTI), Paired Associates Learning Task (PAL), and Stockings of Cambridge items (SOC)]. The two groups were matched for symptom severity. ANOVA with repeated measures was employed to determine whether any difference in cognitive scores during a 2-year period was significantly related to the diagnostic status. RESULTS: A significant and durable difference was observed between SZ and SA on motor screening and explicit memory tests where SA performed better. CONCLUSION: Neurocognitive tests may be relevant for distinguishing schizoaffective from schizophrenia, chiefly via tests tapping into visuo-spatial and visuo-motor coordination abilities (e.g., paired associated learning and motor screening).     

The self-organizing consciousness

We propose that the isomorphism generally observed between the representations composing our momentary phenomenal experience and the structure of the world is the end-product of a progressive organization that emerges thanks to elementary associative processes that take our conscious representations themselves as the stuff on which they operate, a thesis that we summarize in the concept of Self-Organizing Consciousness (SOC).     

Come with me: experimental evidence for intentional recruitment in Tonkean macaques

Animal Cognition - Recruitment is a process by which animals can initiate collective movements: the action of an individual prompts conspecifics to follow. Although it has been hypothesized that...     

Time-dependence between upper arm muscles activity during rapid movements: Observation of the proportional effects predicted by the kinematic theory

Rapid human movements can be assimilated to the output of a neuromuscular system with an impulse response modeled by a Delta-Lognormal equation. In such a model, the main assumption concerns the cumulative time delays of the response as it propagates toward the effector following a command. To verify the validity of this assumption, delays between bursts in electromyographic (EMG) signals of agonist and antagonist muscles activated during a rapid hand movement were investigated. Delays were measured between the surface EMG signals of six muscles of the upper limb during single rapid handwriting strokes. From EMG envelopes, regressions were obtained between the timing of the burst of activity produced by each monitored muscle. High correlation coefficients were obtained supporting the proportionality of the cumulative time delays, the basic hypothesis of the Delta-Lognormal model. A paradigm governing the sequence of muscle activities in a rapid movement could, in the long run, be useful for applications dealing with the analysis and synthesis of human movements.     

La influencia de la ecología,la cultura y el contacto con la civilización europea en el desarrollo cognitivo de los aborígenes australianos

RESUMEN

Este artículo describe un estudio sobre el desarrollo cognitivo de dos grupos de aborígenes australianos que diferían en su grado de contacto con la civilización europea e intenta relacionar el ritmo de desarrollo en distintas áreas con las características ecológicas y culturales. Se incluyen diversas consideraciones que clarifican ambas variables -el grado de contacto y la ecológica/cultural- y seguidamente se presentan las hipótesis, el método y los resultados de la investigación. Por último se discuten éstos en relación con las tres hipótesis, destacando en las conclusiones que la “ambientalidad” cognitiva no es favorable para el desarrollo del pensamiento operacional, el contacto con la civilización europea proporciona algo de esa “ambientalidad” y los factores ecológico-culturales favorecen el desarrollo de ciertas áreas conceptuales más que otras.