A multimethod investigation of the behavioral activation system in bipolar disorder

Dysregulation in behavioral activation system (BAS) activity has been implicated in the pathogenesis of bipolar disorder (BPD). To characterize BAS activity and related facets in this disorder, the authors compared 59 participants with BPD to 44 controls on multiple measures of BAS activity, including a standardized behavioral task, self-reports, and electroencephalographic indexes of regional cortical activity. Levels of putative BAS activity differed depending on assessment strategy. When a behavioral task indexing reward sensitivity was used, euthymic BPD patients showed evidence of higher BAS activity than either control participants or patients who were in a mood episode. Following a mood induction procedure designed to elicit BAS activity, currently episodic patients showed relatively greater left anterior cortical activity than either euthymic or control participants. Implications of the findings for future research on BPD vulnerability are described.     

Induction produced by upcoming food-pellet reinforcement: Effects on subsequent operant responding

Research has demonstrated that rats' rates of operant behavior maintained by 1% sucrose reinforcement in the first half of an experimental session are heightened when food-pellet reinforcers, rather than 1% sucrose, will be available in the second half. Experiment 1 showed that rats that had been displaying this positive induction effect acquired a new response more quickly when 1% sucrose was used to reinforce the novel response than did rats that had not been displaying induction. Experiment 2 showed that this enhanced acquisition remained even when the new response was learned in a new environment. Experiment 3 showed that unconditioned rates of making a new response did not differ between subjects that had or had not been displaying induction. Experiment 4 further showed that significantly different rates of responding on a novel task were not observed when that response was reinforced with a new, non-sucrose reinforcer. Together, the present results suggest that induction results in and/or from an increase in the reinforcing value of the 1% sucrose. As such, the present results have both theoretical and practical implications.     

The Relationship Between Parental Alcoholism and Adolescent Psychopathology: A Systematic Examination of Parental Comorbid Psychopathology

The relationship between parental alcohol dependence (with and without comorbid psychopathology) and adolescent psychopathology was examined in a sample of 665 13-17 year-old adolescents and their parents. Results indicated that adolescents who had parents diagnosed with alcohol dependence only did not significantly differ from adolescents who had parents with no psychopathology in regard to any of the measures of psychological symptomatology (substance use, conduct disorder, and depression) or clinical diagnoses (alcohol dependence, marijuana dependence, conduct disorder, or depression) assessed. In contrast, adolescents who had parents diagnosed with alcohol dependence and either comorbid drug dependence or depression were more likely to exhibit higher levels of psychological symptomatology. In addition, adolescents who had parents diagnosed with alcohol dependence, depression, and drug dependence were most likely to exhibit psychological problems. These findings underscore the importance of considering parental comorbid psychopathology when examining the relationship between parental alcoholism and offspring adjustment.     

Making the sour sweet? Upcoming food-pellet reinforcement produces positive induction when rats press a lever for unsweetened lemon juice

Research has suggested that rats increase their response rate for a low-valued reinforcer when a high-valued reinforcer will soon be available (i.e., positive induction) because the value of the low-valued substance has increased. The present study tested if such a procedure could be used to increase rats’ responding for a non-reinforcing food. Rats pressed a lever for unsweetened lemon juice in the first half of a 50-min session and, in treatment conditions, for food pellets in the second half. Experiment 1 demonstrated that rates of responding for the lemon juice generally varied directly with the upcoming rate of food-pellet reinforcement and that responding in lemon juice-only sessions did not differ significantly from that observed during extinction. Experiment 2 demonstrated that rats consumed more lemon juice following a condition in which they were displaying positive induction than following a condition in which they only responded for lemon juice. The present results are consistent with the increase in value account of positive induction. More importantly, they may indicate that certain environmental conditions can increase food-directed behavior for a non-reinforcing food, a finding which may have implications for our understanding of eating behavior and dysfunctions (e.g., overeating).     

Is induction produced by upcoming food-pellet reinforcement the outcome of an increase in overall activity or in operant responding?

Researchers have demonstrated that rats reliably increase their rates of pressing a lever for 1% liquid-sucrose reinforcement if they will soon have the opportunity to press a lever for food-pellet reinforcement. In the present experiments, the authors investigated if this increase in response rates occurred because the upcoming food pellets produced an increase in all behaviors (i.e., general arousal) or an increase in only the specific operant response (i.e., lever pressing). The results of Experiments 1 and 2 showed that the appearance of induction in rats' lever pressing for 1% sucrose reinforcement when food-pellet reinforcement was upcoming did not coincide with increases in the frequency of running in a wheel or making a nonreinforced nose-poke response. On the other hand, in Experiment 3, the authors found the appearance of induction coincided with increase nonreinforced lever presses on an adjacent lever. These results shed doubt on the idea that induction is a result of a general increase in all activity, and suggest instead that the increase in responding that occurs during induction is limited to the operant response.     

Investigating the devaluation explanation for negative anticipatory contrast

This study addressed whether negative anticipatory contrast results in a decrease in the value of the low-valued substance. Rats responded in training conditions designed to produce negative contrast. They then responded in test sessions in which the low-valued substance from the training sessions was the reinforcer for an operant response. Despite the finding of contrast in the training conditions, the low-valued substance was a more effective reinforcer early in testing after training conditions in which it had been followed by access to the high-valued substance than after training conditions in which it had not. The findings question the devaluation explanation for contrast but may be similar to other findings of reversals of "preference."     

Perceived Genetic Risks for Bipolar Disorder in a Patient Population: An Exploratory Study

Thirty-one subjects with bipolar illness completed a questionnaire about genetic risk for bipolar disorder. Subjects estimated both quantitative and qualitative genetic risk for bipolar disorder for the following categories: general population, siblings, parents, spouses, and children. Results showed that quantitative risks were inflated when compared to qualitative risks and that subjects routinely overestimated the risk for developing bipolar illness. These findings suggest that genetic counseling may be useful for this population.     

Parallel Processing Response Times and Experimental Determination of the Stopping Rule

It was formerly demonstrated that virtually all reasonable exhaustive serial models, and a more constrained set of exhaustive parallel models, cannot predict critical effects associated with self-terminating models. The present investigation greatly generalizes the parallel class of models covered by similar "impossibility" theorems. Specifically, we prove that if an exhaustive parallel model is not super capacity, and if targets are processed at least as fast as non-targets, then it cannot predict such (self-terminating) effects. Such effects are ubiquitous in the experimental literature, offering strong confirmation for self-terminating processing. Copyright 1997 Academic Press. Copyright 1997 Academic Press