Acute effects of aspartame on aggression and neurochemistry of rats.

The inverse relationship between serotonin and aggression was investigated in rats treated with aspartame, a sweetener thought to interfere with the synthesis of this neurotransmitter. Eleven adult, male Long-Evans rats received either aspartame (200-800 mg/kg, IP) or the vehicle prior to testing in a standard resident-intruder paradigm. Contrary to our hypothesis, aspartame significantly decreased aggression as shown by increased latencies to the first attack and decreased number of bites per session. Corresponding with the effects on aggression, aspartame significantly increased striatal levels of serotonin. It was concluded that high doses of aspartame reduced aggressive attack via a serotonergic mechanism while the lower dose was without effect on either variable.

On the importance of evolution to developmental psychobiology.

The term developmental psychobiology implies an integration between psychology and biology. But what segment of biology does the discipline embrace? The present commentary asserts that developmental psychobiology devotes too much attention to structural biology, with its emphasis on proximate mechanisms, and fails to give enough prominence to evolutionary biology and ultimate perspectives. I have attempted to portray the significance of evolution to developmental psychobiology and to elaborate on how developmental psychobiology might contribute to refinements in evolutionary theory, especially recent modifications that advocate a greater role for developmental processes. Methodological suggestions are offered, which would broaden developmental psychobiology's perspective so that a more comprehensive analysis of behavioral development results.

Time-dependent effects of PCPA on social aggression in chicks.

We investigated the effects of para-chlorophenylalanine (PCPA), a serotonin (5-HT) antagonist, on social aggression and brain neurochemistry in young domestic chickens (Gallus domesticus). In Experiment 1, the effects of four different doses of PCPA (0, 100, 200, and 400 mg/kg) were examined for 3 days after injection. Immediately after PCPA injection, aggressive pecking was low and then increased over the 3-day test period. PCPA significantly decreased 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), and 5-HT turnover. In addition, the frequency of aggression was negatively correlated with levels of 5-HIAA. In Experiment 2, the time-dependent effects of a single 400-mg/kg dose of PCPA were examined for 5 and 7 days after drug exposure. PCPA-treated chicks observed for 5 days after injection had significantly greater frequencies of aggression 4 days following drug exposure and significantly reduced 5-HT levels when measured on the next day. Similarly, chicks observed for 7 days exhibited significantly elevated aggression 5 days after injection, after which their pecking decreased to control levels on days 6 and 7. Coinciding with this behavioral pattern, 5-HT levels from these PCPA-treated chicks when assessed 7 days after drug exposure were the same as those for control birds. We concluded that PCPA increased social aggression in birds, an effect that diminished as brain 5-HT levels recovered over a 1-week period.

Tonic immobility and high-intensity calls in a precocial chick as a function of age, diet, and time of day.

Tonic immobility (TI) and high-intensity vocalizations are two antipredator behaviors employed by domestic chicks (Gallus gallus) which vary in their function and the proximate mechanisms that govern them. In the present study, we sought to determine the influence of age (3 or 10 days old), diet (control or tryptophan-free), and time of testing (A.M. or P.M.) on the duration of TI and the number of calls produced in domestic chicks. Older chicks remained immobile significantly longer than younger chicks as did subjects on the control diet or those tested at night. However, 3-day-old chicks had significantly shorter TI durations only when tested in the A.M.: TI did not differ between age groups when subjects were tested in the P.M. Three-day-olds called significantly more than 10-day-olds when given the control diet and when tested in the P.M. but vocalization frequencies did not differ between age groups during the A.M. testing or when given the tryptophan-free diet (T-). Vocalization rate (calls/TI duration), however, was significantly greater during the A.M. testing. These results emphasize the importance of considering circadian rhythms and behavioral development. Furthermore, an integrative view of the proximate mechanisms and adaptive functions of TI and high-intensity vocalizations is presented.

Importance of prenatal nutrition to the development of a precocial chick.

The developmental maturity of hatchling birds varies greatly across the altricial-precocial continuum and these differences are related to the relative proportions of yolk and albumen in a species' egg. In general, the more precocial the chick the greater the proportion of yolk in its egg. Egg composition can also vary within species with unknown consequences for the developing embryo. The present research sought to determine the importance of egg composition to avian development by experimentally removing 1, 2, 4, 8, 12, or 16% of the albumen from eggs of domestic fowl (Gallus gallus). Experimental chicks were paired to control chicks whose eggs were matched on the basis of original mass and laid by the same female but no albumen was removed from their eggs prior to incubation. Decreased levels of albumen significantly decreased chick size at hatch. Experimental subjects, however, had similar growth to controls after 20 days of ad-lib access to food, although sex differences between pairs indicated that the growth of females may be affected differentially by albumen removal. Righting responses were retarded in experimental subjects for the 2 and 4% albumen-removal groups. Egg composition can have important consequences for chick survival simply by influencing body size at hatch and it is suggested that the practice of using overall egg size as a measure of egg "quality" needs to be broadened by considering what is inside the egg as well. In addition, the unique opportunity presented by using an avian model to assess directly the specific influences of protein (albumen) and of fat (yolk) on growth and behavioral development is explored.

The evolution of mental health services: partial hospitalization as a case example.

Controversy exists regarding the current status, merits, and future of partial hospitalization. Originally conceptualized as one of the least restrictive modalities for treating acutely ill or highly impaired individuals in the community, these functions increasingly are being addressed by rehabilitation programs and assertive or intensive outpatient treatments. At the same time, third-party payers, such as managed-care firms, are extending coverage for the partial-hospital modality. We use the current debates about the merits of this modality to identify potential forces that impede and promote the evolution of mental health services. Specifically, we use this case example to illustrate four prevailing myths about the manner in which services evolve.

The promise of partial hospitalization: a reassessment.

In this review of trends in partial hospitalization since 1987, the authors provide a brief overview of the field, summarize recent research findings, examine the data on the growth of partial hospitals, and outline recent changes in public- and private-sector use of this treatment modality. Support for intermediate and long-term partial hospitalization is diminishing rapidly, while support for short-term partial hospitalization as an alternative to inpatient care is increasing in the private sector and diminishing in the public sector. The future for partial hospitals seems uncertain, as the treatment functions of these programs are being assumed by psychosocial and vocational rehabilitation programs and assertive community treatment teams. In light of these trends, the authors recommend new directions for partial hospital research involving comparisons between short-term day hospitalization and intensive outpatient interventions.

A developmental view of therapeutic bonding in the family: treatment of the disconnected family.

Data from an ongoing research study have been used to identify a subgroup of families of severely ill, young adults who present formidable treatment challenges to the family therapist. The disconnected family is characterized by disturbances in attachment between one or both parents and the patient. In many cases, disturbances in attachment and caretaking in the family of origin are reported for the parents in these families. Disconnected families that also have intense emotional styles of relating are particularly difficult to treat. A treatment model that focuses on intergenerational attachment issues is described.

Family system functioning: behavior in the laboratory and the family treatment setting.

The Family System Functioning (FSF) scale is a new instrument for measuring dimensions of the intrafamilial environment thought to be important in recovery from major psychiatric illness. Modest statistical correlations were obtained when FSF ratings of laboratory-based family interactions were compared with researcher-guided therapist ratings of FSF based upon the family's behavior in family therapy sessions during the subsequent month. The data from these two settings provide support for the validity of some of the scales. Because of the modest size of the correlations, however, behavior in the laboratory setting may not always be an accurate indicator of how the family will behave in the early weeks of family therapy.

Continuities in infant memory development.

Fifty-five 6- to 7-month-old human infants were trained in an operant conditioning procedure, adapted from a procedure developed for 3-month-olds, in which kicks were reinforced by conjugate movement of a mobile. Retention was assessed in a simple forgetting paradigm (Expt. 1) or in a reactivation paradigm (Expt. 2) with either the training mobile or a different one serving as the retrieval cue. In Experiment 1, retention was tested 1, 7, 14, or 21 days after training. When the training and test mobiles were the same, infants exhibited virtually no forgetting for 14 days, but forgetting was complete by 21. When the training and test mobiles were different, infants exhibited no retention, discriminating the novel mobile for as long as they could remember the contingency. In Experiment 2, when the training mobile was presented as a reminder, the forgetting previously seen after 21 days was alleviated; when a different mobile was the reminder, it was not. These findings reveal that the efficacy of a reminder is predicted by the efficacy of that same stimulus in cuing the original memory 24 hr following training. Although the 6-month-olds learned more rapidly and remembered longer than infants half their age, their memory processing was described by the same basic principles.

The economics of the law of effect.

A corollary of the law of effect predicts that the larger the reinforcement, the greater the rate of responding. However, an animal must eat more small portions than large portions to obtain the same daily intake, and one would predict, therefore, that when eating smaller portions an efficient animal would eat less (conserving time and energy) and/or respond faster (conserving time). The latter of these predictions was supported by the present experiments with free-feeding rats for which portion size (pellet size or duration of feeder presentation) and portion price within meals were varied. Response rate was a function of the unit price (responses/g) of food: Rats responded faster when portions were smaller or when prices were higher. Meal size and frequency were relatively unaffected by unit price, but were influenced by the price of meal initiation. The results are discussed in relation to the economic differences between traditional operant and free-feeding paradigms and to both traditional and more recent formulations of the law of effect.

Economic evaluation of pharmacologic therapy.

Cost-benefit and cost-effectiveness analyses are defined and described, particularly as they apply to evaluating costs in pharmacologic therapy. The cost-benefit analysis (CBA) approach is used to compare dissimilar alternatives, whereas the cost-effectiveness (CEA) approach compares similar alternatives with similar objectives. A CBA, for instance, will demonstrate the economic effects of a program and can thus be used as a tool to compare the outcomes of several programs. A CEA, on the other hand, can help determine which of several alternatives is the least costly in achieving a stated objective. A CEA approach was used to examine results of clinical trials with cefoxitin or piperacillin in 86 patients undergoing intraabdominal surgery at two institutions. Results of multivariate analysis showed that patients who had received piperacillin had significantly shorter hospital stays (1.59 days) than those who had received cefoxitin. Based on national average hospital per diem rates, piperacillin patients were said to have saved $680 compared with patients treated with cefoxitin. Moreover, piperacillin was less expensive than cefoxitin.

Time budgets in growing chicks.

The manner in which rapidly growing chicks distribute their time among diurnal activities was measured in two studies in which the amount of available light was varied to match seasonal extremes. The effectiveness of the chick's time budgets was assessed in terms of the impact on growth. In Experiment 1, 24-hr patterns of feeding, drinking, nesting, and wheel-running were recorded during successive photoperiods with 12, 6, 18, and 12 hr of light when access to a social partner was concurrently available. In Experiment 2, access to a social partner was an exclusive activity. In both studies, chicks' 24-hr behavioral patterns in response to temporal constraints on their diurnal activities were surprisingly plastic, permitting them to defend a normal and high rate of growth. This was accomplished by changes in feeding rate and by nocturnal feeding rather than by systematic elimination of other diurnal activities. When sociality and feeding were competing activities, feeding time decreased and feeding rate increased such that contact with a conspecific as well as rapid growth were defended. The absolute amount of time spent in measured activities was invariant within subjects irrespective of age, photoperiod, or the number and type of activities recorded, providing evidence of time budgets in immature organisms. In both studies, buffer time (the amount of time spent in no activity) emerged as a significant aspect of the daily time budget that is defended through a variety of environmental challenges.

Cost-effectiveness of two transdermal nitroglycerin controlled-release systems.

An analysis of the cost-effectiveness of two transdermal nitroglycerin systems utilizing adhesive patches, TDN and ND, was performed by a health-care research and management consulting firm. Better adhesion of TDN produced an estimated 14.5% savings over ND ($22.93 vs $26.82) in wholesale prescription costs for four weeks. Multivariate regression analyses, which controlled for patients' age, sex, body mass index, and study location, did not affect the observed difference in adhesive properties, suggesting that TDN's adhesive superiority is intrinsic to patch function and that it does not depend on other variables.