A simple test of the vicarious trial-and-error hypothesis of hippocampal function.

Vicarious trial-and-error (VTE) is a term that Muenzinger and Tolman used to describe the rat's conflict-like behavior before responding to choice. Recently, VTE was proposed as a mechanism alternative to the concept of "cognitive map" in accounts of hippocampal function. That is, many phenomena of impaired learning and memory related to hippocampal interventions may be explained by behavioral first principles: reduced conflicting, incipient, pre-choice tendencies to approach and avoid. The nonspatial black-white discrimination learning and VTE behavior of the rat were investigated. Hippocampal-lesioned and sham-lesioned animals were trained for 25 days (20 trials per day) starting at 60 days of age. Each movement of the head from one discriminative stimulus to the other was counted as a VTE instance. Lesioned rats had fewer VTEs than sham controls, and the former learned much more slowly or never learned. After learning, VTE frequency declined. Male and female rats showed no significant differences in VTE behavior or discrimination learning.     

Asphalt and risk of cancer in man.

Epidemiological publications regarding the carcinogenic potential of asphalt (bitumen) are reviewed. In 1984 the International Agency for Research on Cancer (IARC) stated that there is "inadequate evidence that bitumens alone are carcinogenic to humans." They did, however, conclude that animal data provided sufficient evidence for the carcinogenicity of certain extracts of steam refined and air refined bitumens. In the absence of data on man, IARC considered it reasonable to regard chemicals with sufficient evidence of carcinogenicity in animals as if they presented a carcinogenic risk to man. Epidemiological data for man accumulated since the IARC report do not fulfil the criteria for showing a causal association between exposure to asphalt and development of cancer. The studies cited all suffer from a lack of data on exposure or potential confounders, which are necessary to establish whether or not such an association may or may not exist. In view of the evidence (or lack thereof) regarding asphalt today, an appropriate public health attitude suggests at least that action be taken to protect those working with asphalt by monitoring the workplace, taking whatever steps are possible to minimise exposures and to inform workers of potential hazards. At the same time, a need exists for well designed analytical epidemiological studies to determine whether a risk of cancer in man exists from exposure to asphalt.     

Thoughts about encounters between nondisabled and disabled peers: Situational constraints,states-of-mind,valenced thought categories

This study explores three issues: thoughts and feelings of individuals with and without physical disabilities concerning encounters in different situations, ways of grouping self-statements into valenced categories, and use of states-of-mind (SOM) ratios as an alternative to positive and negative thought frequencies. Data from 127 able-bodied and 46 physically disabled college students indicate that, in everyday social encounters, nondisabled individuals' thoughts and feelings were more negative, while those of disabled individuals were more negative when helping was involved and when encounters centered on the impairment. Thus, problematic encounters between people with and without disabilities may be due to the reactions of individuals with disabilities in situations which involve help, and to reactions of able-bodied persons in everyday contexts. The data also confirm the utility of SOM ratios as an alternative to valenced frequencies in cognitive assessment: SOM scores discriminated groups when situational demands were manipulated and scores were linearly related to criterion measures. However, SOM ratios differed dramatically, depending on the attentional focus of thoughts. The findings illustrate types of thoughts which occur during interaction between people with and without disabilities, demonstrate a simple technique for grouping thoughts into valenced categories on an empirical basis, and highlight the relative contribution of cognitive and affective elements to overall valenced scores. Implications for research on assessment of self-statements are discussed and recommendations are made concerning programming to facilitate the social integration of people with disabilities.This research was supported by grants to the first author from the Social Sciences and Humanities Research Council of Canada and from Fonds F.C.A.R. pour l'aide et le soutien à la recherche. Thanks are due to Meribah Aikens, Maria Barile, Leo Bissonette, Bosco Daude, Jim Dubois, Lillian Fox, Evelyn Gold, Naomi Goodz, Darlene Judd, André Leblanc, John Martos, Sue McKenzie, Irwin Slopak, and Joan Wolforth for their assistance with various stages of this investigation.     

Disentangling Desire and Arousal: A Classificatory Conundrum

A controversial proposal to collapse sexual disorders of desire and arousal is forthcoming in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) (DSM-5). Yet, no study has attempted to empirically distinguish these disorders by using explicit criteria to recruit and compare distinct groups of low desire and arousal sufferers. The goal of the current study was to test the feasibility of finding medically healthy men and women meeting clearly operationalized DSM-IV-TR criteria for disorders of desire and/or arousal and compare them to matched controls. To assess operational criteria, participants completed a comprehensive telephone screening interview assessing DSM-IV-TR and DSM-5 criteria, as well as standardized self-report measures of sexual functioning. The use of operationalized DSM-IV-TR criteria to recruit participants led to the exclusion of over 75 % of those reporting sexual difficulties, with the primary reason for exclusion being failure to meet at least one central diagnostic criterion. The application of the DSM-5 criteria was even more restrictive and led to the exclusion of all but four men and one woman using the original four-symptom criteria, and four men and five women using the revised three-symptom criteria. Cluster analyses supported the distinction between desire and genital arousal difficulties, and suggest that different groups with distinct clusters of symptoms may exist, two of which are consistent with the DSM-5 criteria. Overall, results highlight the need for revisions to the diagnostic criteria, which, as they stand, do not capture the full range of many people’s sexual difficulties.     

Sleep Questionnaire Versus Sleep Diary: Which Measure Is Better?

One questionnaire about a typical week's sleep is more convenient than asking individuals to complete daily sleep diaries. Yet, most clinical evaluations and much sleep and insomnia research rely upon self monitoring via daily sleep diaries. These are often problematic to administer and can be reactive. Therefore, we investigated comparability of two measurement modalities (self monitoring and questionnaire) in a sample of 156 community dwelling older adults, both good and poor sleepers. Results indicate significant and high correlations between corresponding scores on a retrospective sleep questionnaire and on 7 days of self monitoring on a daily sleep diary, thereby suggesting that the two measurement modalities are tapping the same domains. There were, however, significant differences between means on several variables, but there was no systematic pattern to the differences. These findings illustrate the need to tailor measurement modality—retrospective or ongoing—to the setting and the purpose of the evaluation.     

NMDA receptor subunit expression following early postnatal exposure to ethanol

Changes in NMDA receptor function following early postnatal exposure to ethanol may be related to the expression of NMDA receptor subunits. Following early postnatal exposure to ethanol, the expression of NMDA receptor subunits was examined. In cortex from ethanol-exposed rat pups at postnatal day 21, NR2A was significantly increased. There was no change in NR2B, thus suggesting that ethanol exposure during the third-trimester equivalent produces distinct effects on the NMDA receptor.     

Poor sleepers who do not complain of insomnia: Myths and realities about psychological and lifestyle characteristics of older good and poor sleepers

Psychological adjustment, lifestyle, and sleep parameters were investigated in 634 older community residents. Participants were divided into three categories: good sleepers, poor sleepers experiencing high distress, and poor sleepers experiencing minimal distress. Results indicate that (1) highly distressed poor sleepers manifested an anxious, depressed, negative cognitive-affective set; (2) many coped well with age related changes in sleep quality—they resembled good sleepers in the relative absence of psychological maladjustment they displayed; (3) the three groups had similar lifestyles, but they differed in the cognitive-affective evaluation of their activities, (4) the insomnia complaint is itself multifaceted and is comprised of three distinct elements—difficulty sleeping, distress, and daytime fatigue; (5) sleep practices (e.g., naps, bedtimes) are not implicated in chronic poor sleep; and (6) many commonly held assumptions about sleep disruptions in older individuals are myth rather than reality. Implications for better understanding and treating insomnia in older individuals are discussed.This article was prepared during the tenure of grants from the Conseil Québécois de la recherche sociale, Health and Welfare Canada, and the Direction générale de l'enseignement collégial. We are grateful for the generous support of these organizations. In addition, we would like to thank the dedicated members of our research team: Sally Bailes, Ann Gay, Jason Lavers, John Martos, Kathleen McAdams, Vicki Tagalakis, and most especially, Harriet Lennox for their substantial contribution to this research.Dawson College.Sir Mortimer B. Davis—Jewish General Hospital.Concordia University.McGill University.