HIV-1 encephalopathy among perinatally infected children: Neuropathogenesis and response to highly active antiretroviral therapy

HIV-1 encephalopathy among perinatally infected children in the United States was initially defined by a classic triad of findings that included: (1) developmental delay, (2) secondary or acquired microcephaly, and (3) pyramidal tract neuromotor deficits. The most severe form of this disorder typically occurred among young children who developed rapidly progressive disease in concert with profound immunosuppression, and Pneumocystis jiroveci pneumonitis (PCP). The neuropathogenesis of this disorder appears to involve a cascade of viral products, various cytokines and chemokines, and neurotransmitters which promote ongoing inflammation, excitation, and overstimualtion of the N-methyl-D-aspartate type receptor (NMDAR) system. These subsequently lead to neuronal injury and death secondary to apoptosis or necrosis, astrocytosis, as well as dentritic and synaptic damage. The frequency of the most severe forms of encephalopathy among children has dropped dramatically since the introduction of highly active antiretroviral therapy (HAART). Of concern, however, is the possibility that a more insidious form of this disorder may be occurring presently among older vertically infected children as a result of inadequate penetration of HAART agents into the cerebrospinal fluid (CSF). This paper will review what published data there is as yet that bears on this question.     

Lateral and anterior thalamic lesions impair independent memory systems

Damage to the medial region of the thalamus, both in clinical cases (e.g., patients with infarcts or the Korsakoff's syndrome) and animal lesion models, is associated with variable amnesic deficits. Some studies suggest that many of these memory deficits rely on the presence of lateral thalamic lesions (LT) that include the intralaminar nuclei, presumably by altering normal function between the striatum and frontal cortex. Other studies suggest that the anterior thalamic nuclei (AT) may be more critical, as a result of disruption to an extended hippocampal system. Here, highly selective LT and AT lesions were made to test the prediction that these two regions contribute to two different memory systems. Only LT lesions produced deficits on a preoperatively acquired response-related (egocentric) working memory task, tested in a cross-maze. Conversely, only AT lesions impaired postoperative acquisition of spatial working memory, tested in a radial maze. These findings provide the first direct evidence of a double dissociation between the LT and AT neural aggregates. As the lateral and the anterior medial thalamus influence parallel independent memory processing systems, they may each contribute to memory deficits, depending on lesion extent in clinical and experimental cases of thalamic amnesia.     

Dopamine D2 receptors mediate reversal learning in male C57BL/6J mice

Dopamine is critical for directing goal-oriented behavior. We investigated dopamine D₂ receptor involvement in reversal learning and reinforcement efficacy in mice lacking functional dopamine D₂ receptors and their heterozygous and wild-type littermates. Mice discriminated between two odors to receive a food reinforcer: One odor signaled a reinforcer (S⁺); the other odor signaled no reinforcer (S⁻). After mice learned the S⁺/S⁻ relationship, we inverted the reinforcement contingencies. The necessary number of trials to relearn the new reinforcement contingencies served as our index of reversal learning. Mice lacking functional dopamine D₂ receptors repeatedly failed to inhibit previously reinforced responses during reversal trials. In a separate experiment, mice responded for reinforcers on a progressive ratio schedule of reinforcement. Mice lacking functional dopamine D₂ receptors earned significantly fewer reinforcers than did heterozygous mice. Our results suggest that dopamine D₂ receptors regulate reversal learning and influence the reinforcing efficacy of natural rewards.     

Inferences about the authentic self: when do actions say more than mental states?

Three studies involving 478 undergraduates examined the perceived importance of observable actions versus mental states in revealing the "true self"-the authentic and fundamental nature of a target person. Results suggest that when people have only limited information about a target, they believe that an action is more diagnostic of the individual's true self than the accompanying mental state. When participants have knowledge concerning chronic dispositional tendencies of the target, however, they judge that a chronic mental state is more diagnostic of the true self than a chronic action tendency. Considered together, the findings suggest that people conceptualize the true self as a relatively private entity but nevertheless believe that an action of a little-known person may be particularly informative about that individual. Perceived diagnosticity of the true self was partially mediated by inferences concerning the relative stability of actions versus states but not by inferences of volition.     

Test-retest reliability in performance of persons with hemiparesis tracking by means of compatibly displayed myoelectric feedback derived from upper limb muscles

The aim of this study was to assess whether persons with hemiparesis will yield statistically reliable test-retest tracking performance on a procedure using limb-generated, compatibly displayed, myoelectric video feedback. A convenience sample of 50 inpatients and outpatients with upper extremity involvement of at least six months were recruited. 30 had hemiparesis and had both upper extremities tested. 20 had hemiplegia and had the nonparetic upper extremity tested. Tracking skill was measured as mean tracking error. Repeated measures analysis of variance yielded statistically significant effects of main factors: Response mode, Cursor Feedback, and Session. Extremity tested was not significant. Performance with involved limb, uninvolved limb, isometric mode, and isotonic mode all yielded positive rest-retest correlations. The reliable range of tracking error obtained from subjects with hemiparesis performing a task requiring modulation of compatibly displayed myoelectric output supports the therapeutic rationale for employing compatibly displayed video feedback in the rehabilitation of motor control.     

Cognitive style and plebe turnover at the U.S. Naval Academy

Students entering (N = 1,134) the U.S. Naval Academy class of 2000 were administered the Kirton Adaption-Innovation Inventory on the first day of Plebe Summer, a 7-wk. nonacademic training program completed by all entering students in the summer prior to the freshman year. The mean score on Innovation cognitive style for this sample of plebes was approximately a standard deviation lower than those of five other undergraduate student samples from nonmilitary universities. Furthermore, the 98 plebes who voluntarily withdrew before completing the program scored higher on the average on Innovation than those who remained. Findings suggest that, in terms of Person-Organization fit, plebes with a more innovative cognitive style may, perhaps, be less compatible with the regimentation-style climate of the Academy than those with an Adaptive cognitive style. Further research, however, is needed to specify the relationship between Academy students' cognitive style and other important organizational outcomes.     

Adolescent girls' interpersonal vulnerability to depressive symptoms: a longitudinal examination of reassurance-seeking and peer relationships

A transactional, interpersonal framework involving adolescents' reassurance-seeking and peer experiences may be useful for understanding the emergence of gender differences in depression prevalence during the adolescent transition. Sociometric nominations of peer acceptance/rejection and ratings of friendship quality provided by adolescents and their friends were used to measure peer experiences among 6th-8th-grade adolescents (N=520) over 3 annual time points. After controlling for age and pubertal development, significant but small prospective effects offered mixed support for hypotheses: (a) depressive symptoms and negative peer relations predicted increasing levels of girls' reassurance-seeking; (b) initial levels of reassurance-seeking and depressive symptoms predicted deteriorating friendship quality among girls and low friendship stability, respectively; and (c) reassurance-seeking combined with poor peer experiences predicted increases in girls' depressive symptoms.     

The Role of Self-Esteem and Social Influences in Aggressive Reactions to Interactional Injustice

Two experiments were conducted to examine the potential negative consequences an organization may face in response to perceptions of interactional injustice. Study 1 found that one potentially negative reaction to perceived injustice can be intended retaliation. In addition, study 1 found that individuals with high self-esteem are most likely to respond negatively to a perceived injustice by indicating that they plan to engage in a retaliatory response. Study 2 explored the effects of one’s situation on intended retaliation behavior. The results again indicate that perceptions of interactional injustice are strongly related to intended retaliation behavior. In addition, the study demonstrates that one’s group can have a significant influence on the perceptions of injustice and one’s subsequent reactions to these injustices.     

How does narrative cue children's perspective taking?

Three experiments with a total of 120 children between 4 and 9 years of age revealed systematic errors in the recall of deictic terms from a narrative. In some cases, the terms were inconsistent with the perspective of a protagonist. The errors occurred in all age groups and were at the same level whether the protagonist was "good" or "bad" but were less common in a narrative that did not include a protagonist. The pattern of errors suggests that children adopted a perspective within the narrative. Moreover, it seems that whereas the form of the narrative is sufficient to provoke a shift in perspective, children might find it even easier to adopt a perspective when the narrative content is about a protagonist. It thus seems that the form and the content of the narrative (that it is about a person) can combine to give a strong cue to perspective.