Opioid regulation of spinal cord plasticity: evidence the kappa-2 opioid receptor agonist GR89696 inhibits learning within the rat spinal cord

Spinal cord neurons can support a simple form of instrumental learning. In this paradigm, rats completely transected at the second thoracic vertebra learn to minimize shock exposure by maintaining a hindlimb in a flexed position. Prior exposure to uncontrollable shock (shock independent of leg position) disrupts this learning. This learning deficit lasts for at least 24h and depends on the NMDA receptor. Intrathecal application of an opioid antagonist blocks the expression, but not the induction, of the learning deficit. A comparison of selective opioid antagonists implicated the kappa-opioid receptor. The present experiments further explore how opioids affect spinal instrumental learning using selective opioid agonists. Male Sprague-Dawley rats were given an intrathecal injection (30 nmol) of a kappa-1 (U69593), a kappa-2 (GR89696), a mu (DAMGO), or a delta opioid receptor agonist (DPDPE) 10 min prior to instrumental testing. Only the kappa-2 opioid receptor agonist GR89696 inhibited acquisition (Experiment 1). GR89696 inhibited learning in a dose-dependent fashion (Experiment 2), but had no effect on instrumental performance in previously trained subjects (Experiment 3). Pretreatment with an opioid antagonist (naltrexone) blocked the GR89696-induced learning deficit (Experiment 4). Administration of GR89696 did not produce a lasting impairment (Experiment 5) and a moderate dose of GR89696 (6 nmol) reduced the adverse consequences of uncontrollable nociceptive stimulation (Experiment 6). The results suggest that a kappa-2 opioid agonist inhibits neural modifications within the spinal cord.     

Development of the self-concept during adolescence

Adolescence is a period of life in which the sense of 'self' changes profoundly. Here, we review recent behavioural and neuroimaging studies on adolescent development of the self-concept. These studies have shown that adolescence is an important developmental period for the self and its supporting neural structures. Recent neuroimaging research has demonstrated that activity in brain regions associated with self-processing, including the medial prefrontal cortex, changes between early adolescence and adulthood. These studies indicate that neurocognitive development might contribute to behavioural phenomena characteristic of adolescence, such as heightened self-consciousness and susceptibility to peer influence. We attempt to integrate this recent neurocognitive research on adolescence with findings from developmental and social psychology.     

First impressions and professor reputation: influence on student evaluations of instruction

We examined the effects of professor reputation versus first impressions on student evaluations of instruction. Students in 19 Psychology courses completed course evaluation surveys either before meeting the instructor or 2 weeks into the semester. Both groups then completed the course evaluation again at the end of the semester. Unlike evaluations completed prior to meeting the professor, students’ ratings 2 weeks into the semester did not differ from end-of-semester evaluations. Therefore, students considered first impressions more important than professor reputation as determinants of their end-of-the semester evaluations. Results suggest that students form lasting impressions within the first 2 weeks of classes.

Cognitive processing of body and appearance words as a function of thin-ideal internalization and schematic activation

To better understand how women at risk of body image disturbance respond when their body concerns are activated, we examined attentional and memory biases in undergraduate women with high thin-ideal internalization, an identified risk factor for eating disorders, following priming of body and appearance concerns. Female undergraduates (N = 186) viewed photos of either sports cars or attractive swimsuit models, then completed the Lexical Decision Test, a word recall test, and questionnaires assessing thin-ideal internalization and eating disorder symptomatology. High thin-ideal internalizers did not exhibit cognitive biases predicted by cognitive models of eating disorders, even when their body and appearance concerns were primed by exposure to attractive models. Converging evidence suggests that high-risk non-clinical samples rarely exhibit cognitive biases characteristic of individuals with eating disorders, and, in fact, may actually incorporate ideal appearance into their schemas and preferentially attend to attractive stimuli.     

An interactive multiobjective programming approach to combinatorial data analysis

Combinatorial optimization problems in the social and behavioral sciences are frequently associated with a variety of alternative objective criteria. Multiobjective programming is an operations research methodology that enables the quantitative analyst to investigate tradeoffs among relevant objective criteria. In this paper, we describe an interactive procedure for multiobjective asymmetric unidimensional seriation problems. This procedure uses a dynamic-programming algorithm to partially generate the efficient set of sequences for small to medium-sized problems, and a multioperation heuristic to estimate the efficient set for larger problems. The interactive multiobjective procedure is applied to an empirical data set from the psychometric literature. We conclude with a discussion of other potential areas of application in combinatorial data analysis.Stephanie Stahl is a freelance writer and editor. She can be reached via e-mail at s-stahl@worldnet.att.net.     

Gender-Related Effects in Emotional Responding to Resolved and Unresolved Interpersonal Conflict

The current study examines gender differences in affective responding of 58 men and 52 women to various forms of resolved and unresolved interpersonal disputes. The participants were predominantly Caucasians from middle to upper middle class socioeconomic backgrounds. Resolved disputes were perceived as less angry and more okay and happy, and unresolved disputes evoked more anger than resolved disputes did, with continued fighting evoking more anger than did lapsing into the silent treatment. Women reported feeling more angry than did men during both forms of unresolved disputes, and more happy during arguments ending with either apologies or compromises. Men perceived the actors as more sad and reported feeling more okay during arguments than did women. The results extend findings from the children's literature regarding the effect of resolution on emotional responding, and illustrate important gender differences for adults.     

IQ in childhood and the metabolic syndrome in middle age: Extended follow-up of the 1946 British Birth Cohort Study

IQ in early adulthood has been inversely associated with risk of the metabolic syndrome in midlife. We tested this association in the British 1946 birth cohort, which assessed IQ at age eight years and ascertained the metabolic syndrome at age 53 years based on modified (non-fasting blood) ATPIII criteria. Childhood IQ was inversely associated with risk of the metabolic syndrome, but this association was almost entirely mediated by educational attainment and achieved occupational social class. This may be consistent with a pattern where childhood IQ is strongly associated with outcomes that reflect neurological disorder, such as the degenerative dementias, but less so with common chronic physical diseases of ageing.