Stereotype threat strengthens automatic recall and undermines controlled processes in older adults

The threat of being judged stereotypically (stereotype threat) may impair memory performance in older adults, thereby producing inflated age differences in memory tasks. However, the underlying mechanisms of stereotype threat in older adults or other stigmatized groups remain poorly understood. Here, we offer evidence that stereotype threat consumes working memory resources in older adults. More important, using a process-dissociation procedure, we found, for the first time, that stereotype threat undermines the controlled use of memory and simultaneously intensifies automatic response tendencies. These findings indicate that competing models of stereotype threat are actually compatible and offer further reasons for researchers and practitioners to pay special attention to age-related stereotypes during standardized neuropsychological testing.     

Self-determination: a buffer against suicide ideation

Self-determination was examined as a protective factor against the detrimental impact of negative life events on suicide ideation in adolescents. It is postulated that for highly self-determined adolescents, negative life events have a weaker impact on both hopelessness and suicide ideation than for non-self-determined adolescents. In turn, hopelessness is hypothesized to generate less suicide ideation for highly self-determined individuals. Results from multigroup analyses confirm that both the direct and indirect links between negative life events and suicide ideation were significantly weaker among participants high in self-determination. The protective role of self-determination against negative life events is discussed.     

Kv4 potassium channels modulate hippocampal EPSP-spike potentiation and spatial memory in rats

Kv4 channels regulate the backpropagation of action potentials (b-AP) and have been implicated in the modulation of long-term potentiation (LTP). Here we showed that blockade of Kv4 channels by the scorpion toxin AmmTX3 impaired reference memory in a radial maze task. In vivo, AmmTX3 intracerebroventricular (i.c.v.) infusion increased and stabilized the EPSP-spike (E-S) component of LTP in the dentate gyrus (DG), with no effect on basal transmission or short-term plasticity. This increase in E-S potentiation duration could result from the combination of an increase in excitability of DG granular cells with a reduction of GABAergic inhibition, leading to a strong reduction of input specificity. Radioactive in situ hybridization (ISH) was used to evaluate the amounts of Kv4.2 and Kv4.3 mRNA in brain structures at different stages of a spatial learning task in naive, pseudoconditioned, and conditioned rats. Significant differences in Kv4.2 and Kv4.3 mRNA levels were observed between conditioned and pseudoconditioned rats. Kv4.2 and Kv4.3 mRNA levels were transiently up-regulated in the striatum, nucleus accumbens, retrosplenial, and cingulate cortices during early stages of learning, suggesting an involvement in the switch from egocentric to allocentric strategies. Spatial learning performance was positively correlated with the levels of Kv4.2 and Kv4.3 mRNAs in several of these brain structures. Altogether our findings suggest that Kv4 channels could increase the signal-to-noise ratio during information acquisition, thereby allowing a better encoding of the memory trace.     

Remodeling of the neuronal circuits underlying opiate-withdrawal memories following remote retrieval

Several types of memory display time-dependent reorganization of their underlying neural substrates, but it remains unclear whether affective memories associated with drug effects also follow similar reorganization. Here, we analyzed the neural circuits reactivated by the re-exposure of former dependent rats to the withdrawal-paired environment 1month after conditioning (remote memory) as compared with recent memory (Frenois, F., Stinus, L., Di Blasi, F., Cador, M., & Le Moine, C. (2005) A specific limbic circuit underlies opiate withdrawal memories The Journal of Neuroscience, 25, 1366-1374). C-fos expression showed that the circuits involved in the retrieval of withdrawal memories are partly different when comparing recent and remote reactivation, showing that, like other type of memories, affective memories linked to opiate withdrawal undergo anatomical reorganization, with a shift from extended amygdala regions toward cortical areas.     

Evidence for the Syndrome of Nonverbal Learning Disabilities in Children with Brain Tumors

This study examined the predicted utility of the Nonverbal Learning Disabilities syndrome (NLD) (Rourke, 1995) for characterizing neurocognitive and psychosocial outcomes in 123 children with brain tumors. Children with brain tumors were found to be at high risk of having a specific academic deficit, particularly in arithmetic. Children with arithmetic deficit evidenced a higher rate of impairment on nonverbal tasks than on verbal tasks, whereas children with reading deficit evidenced a higher rate of impairment on verbal tasks than on nonverbal tasks. However, significant differences between children with arithmetic and reading deficits were not found for all of the component features of the NLD syndrome, and arithmetic deficit was not related to treatment with irradiation.     

Creep behaviour of ice single crystals loaded in torsion explained by dislocation cross-slip

Torsion creep experiments are carried out in order to understand the physics of ice plasticity. A dislocation spreading mechanism based on double cross-slip of basal dislocations is proposed to explain the strong plastic anisotropy and the power law relationship between stress and strain rates. The scenario is tested using three-dimensional dislocation dynamics simulations. Numerical investigations give a stress exponent n?=?2.3 in agreement with experimental measurements. This dislocation spreading mechanism sheds a new light on the interpretation of former experimental observations.     

Experimental philosophers,conceptual analysts,and the rest of us

Abstract

Theories of personal identity purport to specify truth conditions for sentences of the form ‘x‐at‐t_i is the same person as y‐at‐t_j. Most philosophers nowadays agree that such truth conditions are to be stated in terms of psychological continuity. However; opinions vary as to how the notion of psychological continuity is to be understood. In a recent contribution to this journal, Slors offers an account in which psychological continuity is spelled out in terms of narrative connectedness between mental states.The present paper argues that Slors’ theory either is no theory of personal identity at all or is too weak.Towards the end of the paper, it is indicated how the problem uncovered for Slors’ theory may be avoided.