Hippocampal synaptic plasticity during instrumental learning

present research examined the role of hippocampal NMDA-dependent synaptic potentiation on appetitive instrumental conditioning under a continuous reinforcement schedule. In the first experiment, low (.025 mg.kg) or moderate (.05 mg/kg) dosages of the NMDA receptor antagonist, MK801, failed to increase the number of training days required to reach acquisition criterion; number of training days required to reach criterion for extinction were also unaffected. In the second experiment, a higher dosage (.10 mg/kg) of MK801 or induction of long-term potentiation failed to alter the number of responses occurring during acquisition. These data suggest that hippocampal synaptic potentiation does not play a prominent role in instrumental learning with simple contingency conditions. It is suggested that hippocampal LTP reflects a perceptual process that contributes differentially to spatial cognition, classical and instrumental conditioning.     

Hippocampal synaptic plasticity during instrumental learning

present research examined the role of hippocampal NMDA-dependent synaptic potentiation on appetitive instrumental conditioning under a continuous reinforcement schedule. In the first experiment, low (.025 mg.kg) or moderate (.05 mg/kg) dosages of the NMDA receptor antagonist, MK801, failed to increase the number of training days required to reach acquisition criterion; number of training days required to reach criterion for extinction were also unaffected. In the second experiment, a higher dosage (.10 mg/kg) of MK801 or induction of long-term potentiation failed to alter the number of responses occurring during acquisition. These data suggest that hippocampal synaptic potentiation does not play a prominent role in instrumental learning with simple contingency conditions. It is suggested that hippocampal LTP reflects a perceptual process that contributes differentially to spatial cognition, classical and instrumental conditioning.     

The nature and treatment of social phobia in youth

A small proportion of children and adolescents experience a debilitating level of social anxiety, known as social phobia. Initially, we consider the phenomenology and aetiology of social phobia in children and adolescents. A number of age-sensitive assessment instruments or tools are briefly considered: a diagnostic interview, selj-report instruments, behavioural observations, cognitive assessment, self-monitoring and psychophysiological recording. We explore cognitive-behavioural strategies that have been found to be useful in the management of social phobia. Although there is much research support for the efficacy of cognitive-behavioural strategies for adults with social phobia, it is emphasized that controlled evaluations have yet to be undertaken with socially phobic youngsters.     

Public knowledge,attitudes, and beliefs about homeless people: Evidence for compassion fatigue?

Media reports suggest that the public is becoming impatient with the homeless—that so-called “compassion fatigue” has gripped the nation. This characterization of public sentiment could have important policy consequences—restrictive measures can be justified by growing public impatience, and progressive housing policies seem infeasible within a hostile climate of opinion. But evidence to support the compassion fatigue notion is anecdotal. We examine the issue by tracking the results of public opinion polls and by reporting detailed evidence from a nationwide random-digit dial telephone survey (N=1,507) concerning knowledge attitudes and beliefs about homeless people. To be sure, the public sees homelessness as an undesirable social problem and wants something done about it. However, although the homeless are clearly stigmatized, there is little evidence to suggest that the public has lost compassion and is unwilling to support policies to help homeless people.     

“My big sister the town supervisor”: Family leadership training is not just for boys

This study investigates gender similarity in the effects of birth order upon political leadership. Town supervisors were the leaders studied as there are a considerable number of women who attain this level of leadership. Questionnaires about birth order and family size were gained from 66 women who were town supervisors in New York State in 1992, and compared to a randomly selected sample of 57 male town supervisors. It was found that women as well as men town supervisors were more likely to have been first born in their families. However, whereas gender does not apparently influence the relevance of birth order for leadership, it clearly does exert an influence on the level of political leadership attained. Women town supervisors gained their positions in towns that were considerably smaller than the towns led by the male supervisors. Discussion concerned the nature of family experiences that contribute to leadership training, including those that may be different for girls and boys. Further research is needed to clarify barriers to female assertion of political leadership at more senior levels, because as this study shows, female leadership is being trained in families.     

Three- and four-year-olds’ perceptual confusions for spoken words

Although infants have the ability to discriminate a variety of speech contrasts, young children cannot always use this ability in the service of spoken-word recognition. The research reported here asked whether the reason young children sometimes fail to discriminate minimal word pairs is that they are less efficient at word recognition than adults, or whether it is that they employ different lexical representations. In particular, the research evaluated the proposal that young children’s lexical representations are more “holistic” than those of adults, and are based on overall acoustic-phonetic properties, as opposed to phonetic segments. Three- and four-year-olds were exposed initially to an invariant target word and were subsequently asked to determine whether a series of auditory stimuli matched or did not match the target. The critical test stimuli were nonwords that varied in their degree of phonetic featural overlap with the target, as well as in terms of the position(s) within the stimuli at which they differed from the target, and whether they differed from the target on one or two segments. Data from four experiments demonstrated that the frequency with which children mistook a nonword stimulus for the target was influenced by extent of featural overlap, but not by word position. The data also showed that, contrary to the predictions of the holistic hypothesis, stimuli differing from the target by two features on a single segment were confused with the target more often than were stimuli differing by a single feature on each of two segments. This finding suggests that children use both phonetic features and segments in accessing their mental lexicons, and that they are therefore much more similar to adults than is suggested by the holistic hypothesis.     

Vasopressin, glucose homeostasis, and sucrose taste preferences

Previous research indicates that vasopressin-containing (LE) rats are capable of adapting to the stress of food restriction, whereas vasopressin-deficient (DI) rats cannot adapt to this stressor. It has been postulated that abnormalities in glucose metabolism may be one of the factors leading to the demise of food-restricted DI rats. The present study was conducted to determine if taste preferences are altered in DI animals and if the presentation of exogenous glucose, in the form of sucrose solutions, can ameliorate the effects of the stress of food restriction. Four different concentrations of sucrose solutions were presented to LE and DI rats under the food-restricted condition. In both strains, an 8% sucrose solution was preferred over 0%, 16%, and 32% concentrations, with DI rats consuming more of this concentration than LE rats. Thus, when DI rats had the opportunity of maintaining glucose homeostasis by exogenous supplements, they maintained body weight, displayed no stomach pathology, and survived.     

Death,sin, and God's judgment

Grief is difficult for everyone, including the professional. And yet resolving grief is necessary for life to be comfortable and productive. This paper looks at the story of a young man and how unresolved grief, inappropriate guilt, and uncontrollable despair colored every phase of his life. It also demonstrates the tragedy when grief is allowed to remain in denial and resolution comes too late.     

Prosodic influences on the resolution of temporary ambiguity during on-line sentence processing

We present three experiments designed to investigate the role of prosody during sentence processing. The first investigated the question of whether an utterance's prosodic contour influences its comprehension on-line. We spliced the beginning and end portions of direct object and embedded clause sentences and observed the consequent effects on comprehension using a dual-task procedure to measure processing load. Our second experiment sought to determine-whether the constituent structure of these sentences could be reliably predicted using prosodic information. We found that the duration and F₀ contour associated with the main-clause verb and the following NP reliably distinguished between the direct object and embedded clause constructions. In the final experiment, we manipulated the duration of the main-clause verb and found that subjects used this information to guide their initial parse during on-line sentence comprehension. The need for a model of sentence processing that addresses the use of prosodic information is discussed.The work reported in this paper was supported in part by NTH grant DC00494.     

Predicting Adolescents' Initiation of Intercourse and Contraceptive Use

This paper examines whether variables consistent with problem behavior theory predict grade of onset of first intercourse and adoption of effective contraception. A total sample of 3,419 Wisconsin adolescents in Grades 7, 9, and 11 participated in a survey of health-related behaviors administered 3 times across a 6-year period. The sample is 87% White. Multiple regression methods generated different models for onset of sexual intercourse vs. contraceptive adoption. Consistent with problem behavior theory, sexual onset is predicted by the adolescent's behavioral system, perceived peer substance use/abuse, importance of friends, and extent to which the adolescent felt harried and believed it was okay to break laws. Contraceptive adoption is predicted by family structure, socioeconomic variables, and self-esteem. Age and gender model differences emerged.