Place learning in scopolamine-treated rats: the roles of distal cues and catecholaminergic mediation

Experiments 1 and 2 tested the hypothesis that cholinergic receptor antagonists impair place learning in a water maze by interfering with the processing of distal, visual cues. Extramaze cues were offered to rats in the form of geometrical patterns arranged on the inner circumference of a curtain surrounding the water maze. In Experiment 1 the animals were offered both the distal cues and proximal cues in the form of pingpong balls in fixed positions on the surface of the water while only distal cues were present in Experiment 2. Animals were injected with either scopolamine (0.5 mg/kg body wt) or saline 20 min prior to the daily place learning sessions. Upon reaching criterion level performance the animals were tested on "rotation" sessions on which the distal cues were displaced. The outcome of such "rotations" demonstrated that-regardless of the presence or absence of proximal cues-scopolamine-treated rats relied at least as much as normal animals on the distal cues. The acquisition phase of both Experiments 1 and 2 demonstrated an almost complete lack of scopolamine-associated impairment in acquisition and performance of the place learning task. In Experiment 3 (when scopolamine was no longer administered) the subjects of Experiment 2 were exposed to a series of pharmacological "challenges" of their place learning performance and eventually to surgical ablation of the anteromedial prefrontal cortex. The outcome of the pharmacological challenges and the postoperative test of task performance demonstrated that the place learning performance of animals which had acquired the task under scopolamine was mediated by a neural substrate dissimilar to the substrate of task performance in normal animals. Rats acquiring the task while deprived of the cholinergic system demonstrated above-normal contributions to task mediation from catecholaminergic-probably dopaminergic-mechanisms and tentative results pointed to a "shift" toward prefrontal task mediation.     

Primary care physicians attitude toward diagnosis and treatment of late-life depression

Underdiagnosis and undertreatment of late-life depression is common, especially in primary care settings. To help assess whether physicians attitude and confidence in diagnosing and managing depression serve as barriers to care, a total of 176 physicians employed in 18 primary care groups were administered surveys to assess attitudes towards diagnosis, treatment, and management of depression in elderly patients, (individuals over 65 years of age). Logistic regression was performed to assess the association of physician characteristics on attitudes. Nearly all of the physicians surveyed felt that depression in the elderly was a primary care problem, and 41% reported late-life depression as the most common problem seen in older patients. Physicians were confident in their ability to diagnose and manage depression, yet 45% had no medical education on depression in the previous three years. Physicians confidence in their ability to diagnose, treat, and manage depression, and their reported adequacy of training, do not appear to correspond to the amount of continuing medical education in depression, suggesting that physician overconfidence may potentially be serving as a barrier to care.     

The relevance of Rawls' principle of justice for research on cognitively impaired patients

An ethical conflict arises when we must performresearch in the interest of future patients,but that this may occasionally injure theinterests of today's patients.In the case of cognitively impaired persons, thequestion arises whether it is compatible withhumane healthcare not only to treat, but alsoto use these patients for research purposes.Some bioethicists and theologians haveformulated a general duty of solidarity, alsopertaining to cognitively impaired persons, as ajustification for research on these persons. Ifone examines this thesis from the theory ofjustice according to John Rawls, it is revealedthat such a duty of solidarity cannotnecessarily be extrapolated from Rawls'conception of justice. This is at least true ofRawls' difference principle, because accordingto the difference principle only those measuresare justifiable which serve the interest of therespective least well off. Those measures whichwould engender additional injury for the leastwell off could not be balanced by any utilityaccording to Rawls.However, John Rawls' difference principleis subordinate to the first principle,which is that each person has an equalright to the most extensive basic libertycompatible with the same liberty for others.These primary goods are determined by thefreedom and integrity of the person.This integrity of decisionally impaired personswould be in danger if one would abstain fromresearch and thus forego the increase inknowledge related to their disease. Thus onecould conclude, at least from Rawls' firstprinciple, that society must take on a duty toguarantee the degrees of freedom forcognitively impaired persons and thus alsosupport the efforts for their healing.     

Win-shift and win-stay learning in the short-beaked echidna (<Emphasis Type="Italic">Tachyglossus aculeatus</Emphasis>)

Numerous previous investigators have explained species differences in spatial memory performance in terms of differences in foraging ecology. In three experiments we attempted to extend these findings by examining the extent to which the spatial memory performance of echidnas (or "spiny anteaters") can be understood in terms of the spatio-temporal distribution of their prey (ants and termites). This is a species and a foraging situation that have not been examined in this way before. Echidnas were better able to learn to avoid a previously rewarding location (to "win-shift") than to learn to return to a previously rewarding location (to "win-stay"), at short retention intervals, but were unable to learn either of these strategies at retention intervals of 90 min. The short retention interval results support the ecological hypothesis, but the long retention interval results do not. Electronic Publication     

Examination of relationships among trait-like individual differences, state-like individual differences, and learning performance

Several authors (e.g., J.T. Austin & H.J. Klein, 1996; R. Kanfer, 1990b, 1992) have urged researchers to examine comprehensive models of distal individual differences as predictors of proximal motivational processes and performance. Two field studies in an academic setting tested a model of relationships among trait-like individual differences (cognitive ability, general self-efficacy, and goal orientation), state-like individual differences (state anxiety, task-specific self-efficacy, and goals), and learning performance. Most hypothesized relationships among these constructs received support when tested on 2 samples, when examining different performance episodes, and when using different goal orientation and state-anxiety measures. In general, state-like individual differences were found to mediate the relationships between trait-like individual differences and learning performance. Implications of these results are discussed and suggestions for future research are provided.     

Stress and alcohol use: a daily process examination of the stressor-vulnerability model

The authors used a daily diary methodology to examine over 60 days how the within-person associations among event stress, alcohol consumption, and desire to drink varied as a function of gender, positive and negative alcohol-outcome expectancies, and avoidant coping in a sample of 88 regular drinkers. Multilevel regression analyses indicated that men who more strongly anticipated positive outcomes or a sense of carelessness from drinking drank relatively more on stressful days compared with low-stress days. Similar results were found predicting desire to drink. Men who anticipated greater impairment from drinking drank relatively less on stressful days. In general, these effects did not hold for women. Little evidence was found for the predicted effects for avoidant coping style, and some results showed that avoidant coping style buffered the exacerbating effects of careless unconcern expectancies.     

Attending, ignoring, and repetition: on the relation between negative priming and inhibition of return

A series of spatial localization experiments is reported that addresses the relation between negative priming and inhibition of return. The results of Experiment 1 demonstrate that slowed responses to repeated location stimuli can be obscured by repetition priming effects involving stimulus dimensions other than spatial location. The results of Experiments 2, 3A, and 3B demonstrate that these repetition priming effects may occur only when participants are required to respond to the prime display. Together, these results suggest that differences between attended and ignored repetition effects in selective attention studies of spatial localization do not provide a basis for distinguishing between spatial negative priming and inhibition of return.     

Gamma-range oscillations in backward-masking functions and their putative neural correlates

Backward-masking functions have been hitherto categorized into two types, commonly named Type A and Type B. The analysis of a model of Retino-Cortical Dynamics produces the prediction that spatially localized stimuli should reveal an oscillatory metacontrast function. The predicted new type of metacontrast masking function was investigated in a psychophysical experiment. The results show oscillatory metacontrast functions with significant power in the gamma range (30-70 Hz). A marked decrease in the oscillations is observed when the spatial extent of the stimuli is increased. The theoretical basis of the study relates the oscillations found in the metacontrast function to gamma-range oscillations observed in scalp and intracerebral recordings. The qualitative agreement between the model and data provides support for this putative relationship.     

Role of the working alliance in the treatment of delinquent boys in community-based programs

Examined the role of the working alliance in the treatment of delinquent boys in community-based residential programs, clarifying the relation between therapeutic process and behavioral change. Horvath and Greenberg's (1989) Working Alliance Inventory was used to assess the therapeutic alliance between youth and staff after 3 weeks in treatment and again after 3 months. Achenbach's (1991) Child Behavior Checklist (CBCL; Youth Self-Report [YSR] and Teacher Report Form [TRF]) and recidivism scores were used to assess treatment progress and outcome. Results indicated that a positive working alliance assessed after 3 months in treatment related to positive psychological changes and predicted lower rates of recidivism. Unexpectedly, a positive working alliance assessed early in treatment was associated with negative outcomes (increased internalizing and externalizing symptoms and higher rates of recidivism). This finding suggests that for some delinquent youth initially optimistic assessments may be prognostic of slow progress or treatment failure.