Activity-Dependent Activation of TrkB Neurotrophin Receptors in the Adult CNS

In this paper we have investigated the hypothesis that neural activity causes rapid activation of TrkB neurotrophin receptors in the adult mammalian CNS. These studies demonstrate that kainic acid-induced seizures led to a rapid and transient activation of TrkB receptors in the cortex. Subcellular fractionation demonstrated that these activated Trk receptors were preferentially enriched in the synaptosomal membrane fraction that also contained postsynaptic glutamate receptors. The fast activation of synaptic TrkB receptors could be duplicated in isolated cortical synaptosomes with KCl, presumably as a consequence of depolarization-induced BDNF release. Importantly, TrkB activation was also observed following pharmacological activation of brain-stem noradrenergic neurons, which synthesize and anterogradely transport BDNF; treatment with yohimbine led to activation of cortical TrkB receptors within 30 min. Pharmacological blockade of the postsynaptic α1-adrenergic receptors with prazosin only partially inhibited this effect, suggesting that the TrkB activation was partially due to a direct effect on postsynaptic cortical neurons. Together, these data support the hypothesis that activity causes release of BDNF from presynaptic terminals, resulting in a rapid activation of postsynaptic TrkB receptors. This activity-dependent TrkB activation could play a major role in morphological growth and remodelling in both the developing and mature nervous systems.     

The value of children: theory and method

Psychological research into the determinants of family size pertains to the motivations connected with childbearing in general and to those relating to specific numbers of children or family size. 1 model defines the variables affecting such motivations as: 1) the value of children; 2) alternate sources of value; 3) costs, 4) barriers, and 5)facilitators. An ongoing cross cultural study is discussed and the questionnaires used in the study as well as the preliminary results are given. It is felt that the knowledge gained through such research will help in the design of social policies that influence couples to regulate family size to levels that are congruent with personal desires as well as societal goals.     

COMPARING PLEASURE AND PAIN: THE FUNDAMENTAL MATHEMATICAL EQUIVALENCE OF REWARD GAIN AND SHOCK REDUCTION UNDER VARIABLE INTERVAL SCHEDULES

The relationship between positive and negative reinforcement and the symmetry of Thorndike's law of effect are unresolved issues in operant psychology. Here we show that, for a given pattern of responding on variable interval (VI) schedules with the same programmed rate of food rewards (positive reinforcement VI) or electric shocks (negative reinforcement VI), there is a fundamental mathematical equivalence between reward gain and shock reduction. We also provide the first normative account of how animals should respond on a negative VI schedule, showing that it is better to space responses evenly than to respond with a variable interresponse time (IRT). Published data from rats, however, indicate that these animals respond irregularly, often with a burst of activity immediately following a shock. While this is irrational in the experimental setting, it may represent an appropriate response to the heterogeneity of stimuli commonly encountered in natural environments. We discuss the broader implications of our analysis for understanding how animals evaluate appetitive and aversive stimuli.     

Somatoform Disorder: Treatment Utilization and Cost by Mental Health Professions

Administrative data from Cigna for 149 somatoform cases were analyzed to determine the cost, number of sessions, dropout rates, and recidivism rates. Comparisons on these outcomes were made between medical doctors, psychologists, master’s nurses, master’s social workers, marriage and family therapists, and professional counselors. Recidivism rates and number of sessions are higher than for other mental health problems. There were no significant difference in total cost by profession, but did indicate a significant difference in cost per session for MDs. Analyses indicate that masters and doctoral level providers produced the same drop out and recidivism rates.     

Does an instruction to forget enhance memory for other presented items?

In an item-method directed forgetting paradigm, participants were required to attend to one of two colored words presented on opposite sides of a central fixation stimulus; they were instructed to Remember or Forget the attended item. On a subsequent recognition test, the Attended words showed a typical directed forgetting effect with better recognition of Remember words than Forget words. Our interest was in the fate of the Unattended words. When the study display disappeared before the memory instruction, there was no effect of that instruction on unattended words; when the study display remained visible during presentation of the memory instruction, there was a reverse directed forgetting effect with better recognition of unattended words from Forget trials than from Remember trials. Incidental encoding of task-irrelevant stimuli occurs following presentation of a Forget instruction - but only when those task-irrelevant stimuli are still visible in the external environment.     

What is the mechanism by which suicide attempts predispose to later suicide attempts? A mathematical model

A state dependence model of serial behavior suggests that each occurrence increases the subsequent likelihood of that behavior being repeated. A heterogeneity model, by contrast, suggests that the likelihood of a behavior occurring is predetermined, and uninfluenced by intervening occurrences. We have applied the random-effects probit model of Gibbons and Bock (1987) to examine the fit of the state dependence and heterogeneity models to longitudinal data on suicide attempts by 928 patients with affective disorder. Heterogeneity but not state dependence was required to model these data. The findings suggest that when considering patients with moderate to severe major affective disorder, the clinician should not interpret the absence of any recent suicide attempts to mean that the patient is at relatively low risk for attempting suicide in the future. An implication of the heterogeneity model is that suicide attempts made many years ago may have equal value to recent attempts when estimating an individual's "predisposition" to nonlethal attempts in the future.     

Automaticity: a new framework for dyslexia research?

The performance of a group of 23 13-year-old dyslexic children was compared with that of same-age controls on a battery of tests of motor balance. A dual-task paradigm was used--subjects performed each test twice, once as a single task, and once as a dual task concurrently with a secondary task. Two alternative secondary tasks were used, the classic counting-backwards task and an auditory choice reaction task. Both secondary tasks were calibrated for each subject to ensure that their performance on the secondary task alone fell between pre-specified performance criteria. In all single-task conditions there was no difference between the performance of the two groups. By contrast, in 19 out of the 20 tests performed under dual-task conditions, the dyslexic group were significantly impaired, whereas the controls showed no impairment, thus resulting in significantly better performance by the control group than the dyslexic group. The sole exception was that the dyslexic children were not impaired on the easiest balance condition with the choice reaction task. Under the dual-task conditions the dyslexic children also performed worse than the controls on the secondary task. It is very hard to accommodate the findings within the traditional framework of a deficit specific to lexical skills. One plausible explanation of the results is that, unlike the controls, the dyslexic children need to invest significant conscious resources for monitoring balance, and thus their performance is adversely affected by any secondary task which serves to distract attention from the primary task. This need for "conscious compensation" suggests that for dyslexic children the skill of motor balance is poorly automatized. It is possible, therefore, that many of the reading deficits of dyslexic children are merely symptoms of a more general learning deficit--the failure to fully automatize skills.     

Using empowerment theory in collaborative partnerships for community health and development

Models of community empowerment help us understand the process of gaining influence over conditions that matter to people who share neighborhoods, workplaces, experiences, or concerns. Such frameworks can help improve collaborative partnerships for community health and development. First, we outline an interactive model of community empowerment that describes reciprocal influences between personal or group factors and environmental factors in an empowerment process. Second, we describe an iterative framework for the process of empowerment in community partnerships that includes collaborative planning, community action, community change, capacity building, and outcomes, and adaptation, renewal, and institutionalization. Third, we outline activities that are used by community leadership and support organizations to facilitate the process of community empowerment. Fourth, we present case stories of collaborative partnerships for prevention of substance abuse among adolescents to illustrate selected enabling activities. We conclude with a discussion of the challenges and opportunities of facilitating empowerment with collaborative partnerships for community health and development. This work was supported by Kansas Health Foundation Grants 9206032B and 9206032A to support and evaluate community partnerships to prevent adolescent substance abuse. Thanks to Tom Wolff for sharing his wisdom about community coalitions so generously, and to Bill Berkowitz and anonymous reviewers for thoughtful comments on an earlier version of this manuscrpt. We also thank our colleagues from the Kansas Health Foundation, Mary K. Campuzano, Steve Coen, and Marni Vliet, and those from collaborating communities, who continue to teach us about ways to enhance community capacities to address local concerns.