Behavior in adulthood and during aging is affected by contaminant exposure in utero

Environmental contaminants can alter the course of neural development, with consequences that appear in behavior. Such effects extend into adulthood and sometimes accelerate the rate of aging, even when exposure ceases by birth. The neurotoxicant methylmercury provides an interesting case study that reveals much about how disrupted neural development has lifelong consequences. Methylmercury also provides an example of the assessment and management of risks associated with exposure to developmental neurotoxicants.     

The problem of unconsciousness in qualitative research

Although reflexivity is critical to the practice of qualitative research, the problem of unconsciousness seems to stand in its way. If aspects of lived experience are unconscious to an engaged participant, then how can one become reflexive? This paradox, and the problems it poses for qualitative research, are discussed. Varying conceptualisations of unconsciousness are presented. Unconsciousness can be understood as revealed through language, as primarily non-verbal, or as ultimately irrelevant to human experience. In addition, the source of unconscious material can be conceptualised as internal and subjective, or as contextual and direcdy observable. From these assumptions follow diverse approaches to qualitative research. If unconsciousness is structured via language, then research must focus on the words through which participants describe their experience. If, however, unconsciousness is distinct from language, then qualitative methods must incorporate non-verbal data. The presumed locus of unconsciousness will also affect one's research methods. Internal explanations require querying the subject, and external explanations entail scrutinising context. Examples of qualitative methods and the diverse approaches from which they proceed are presented It is argued that reflexivity demands scrutiny and articulation of the verbal, non-verbal and contextual components that define a particular research project. The author details his own experiences in this regard, and outlines areas in need of further methodological development.     

Chlordiazepoxide-induced working memory impairments: site specificity and reversal by flumazenil (RO15-1788).

The following studies examined the dose and time dependence, site specificity, and reversibility of chlordiazepoxide (CDP)-induced working memory impairments in adult male Sprague-Dawley rats. The rats were tested in a delayed non-match-to-sample radial-arm maze task in which a 1-h delay was imposed between the first four (predelay) and all subsequent (postdelay) arm choices. Intraperitoneal (ip) injection of 2.5 or 5.0 but not 1.25 mg/kg CDP immediately following the predelay session impaired performance in the task. CDP increased the number of errors and decreased the number of correct choices during the postdelay session. The observed working memory impairments also appeared to be site specific since injection of CDP into the medial septum, but not into the anterior amygdala nuclei, immediately following the predelay session also impaired working memory in a dose-related manner. Furthermore, there was a time window for CDP-induced working memory impairments since intraseptal injection of the drug immediately but not 15 min following the predelay session disrupted memory. This observation suggests that the performance deficits reflect disrupted working memory and not proactive effects on performance or the induction of state-dependent learning. In the final experiment, rats were injected ip with either saline or an amnestic dose of CDP (5.0 mg/kg) following the predelay session and then were immediately infused with 10 nmol flumazenil (RO15-1788), a benzodiazepine receptor antagonist or vehicle, into either the medial septum or anterior nuclei of the amygdala. Intraseptal injection of flumazenil prevented the working memory impairments produced by ip injection of CDP. In contrast, intra-amygdala injection of flumazenil did not attenuate, enhance, or modify the CDP-induced working memory impairment. These observations suggest that CDP disrupts working memory by interacting with benzodiazepine receptors in the medial septum.     

Concurrent validity and Holland's theory

This study was designed to explore two areas: (1) the concurrent validity of Holland's theory for employed men using four different operational definitions of vocational orientation, and (2) the relationships among all possible combinations of same named scales across the four inventories. Concurrent validity was studied by administering the Vocational Preference Inventory, the Self Directed Search, and the Holland Scales (Set I and Set II) to 153 male workers established in occupational environments consistent with Holland's six vocational environments. The results revealed that five scales of the VPI and of the Holland Scales (Set I and Set II) and four scales of the SDS successfully differentiated the occupational groups consistent with Holland's theoretical framework. The correlation coefficients for same named scales for all possible combinations of the four inventories were all found to be significant. In general, the findings of this study tend to support the concurrent validity of Holland's theory for employed men.     

Consistent occupational preferences,vocational maturity,and academic achievement

This study explored the differences in vocational maturity, academic aptitude, and achievement variables among female sorority students who made congruent, incongruent, and undecided occupational choices. The variables were operationally defined by the Career Maturity Inventory, the American College Test Battery, and a self-report questionnaire. Congruent, incongruent, and undecided current occupational choice groups were defined operationally using the Self-Directed Search. The analysis of variance revealed the main effect of groups to be significant for two variables. The findings suggest that students in the congruent female group tend to be more vocationally mature than students in the incongruent and undecided groups.     

Visual onset and offset latencies

An experiment was designed to test the hypothesis that the latency of response to the offset of light can sometimes be shorter than the latency of response to the onset. The subjects' task involved the temporal order discrimination of the offset of one light and the onset of another. The results indicated that offsets were perceived about 40 ms earlier than onsets. Reasons were suggested for the shorter onset latencies found by other investigators, and a model was proposed to account for changes in the relative latencies of onsets and offsets as a function of stimulus duration and intensity.     

Self-directed weight control through eating and exercise

A weight control program using a written contract and other self-control behavior modification techniques for changing eating habits was compared with a similar program concentrating on both eating and exercise behavior and with an attention-placebo control condition. Participants in all three programs lost weight during the 12 week program, with no significant differences between groups. A seven-month follow-up revealed that Ss in the two behavior modification groups lost more than those in the control group and that those in the eating plus exercise group lost more than those in the group dealing only with eating behavior.