Julie C. Stout - US grants

In a recent reports using a simulated gambling task, Bechara, Damasio, and their colleagues propose that in a risky decision making context, people employ somatic guidance to facilitate selection of advantageous response alternatives. As a central piece of evidence, they demonstrate thatsubjects with ventromedial frontal lobe (VMF) damage perform poorly on the gambling task, and that in contrast to healthy subjects, VMF subjects have diminished anticipatory skin conductance responses (SCRs) prior to making disadvantageous selections. These findings have provoked a great deal of interest because they suggest a model for studying how problems in decision making might be linked to failures to integrate affective influences into decision processes. The utility of the gambling task/SCR paradigm in VMF-lesioned subjects is limited because of the rarity of these frontal lobe subjects, the complexity of interpreting gambling task outcomes, and the plethora of cognitive processes that play into a complex decision-making task. The goal of the pilot study proposed in the B/START application is to expand this model of decision making by extending the model to Huntington's disease (HD). HD affects subcortical structures which, in turn, alter functioning of the VMF circuit. Similar to subjects with VMF damage, HD is associated with problems in daily life associated with poor decision making. HD is also associated with deficits in gambling task performance. The proposed study will determine whether gambling task performance is linked to SCRs in HD. The study will provide essential data, such as effect sizes, for designing a more extensive study of the interplay between psychophysiological, neurobehavioral, and cognitive processes in decision making. Improved understanding of the interplay between emotion and cognition is important given evidence of risky behaviors and deficits in judgement in a variety of psychopathological and neurological conditions.

DESCRIPTION: (provided by applicant) Clinical neuroscientists have recently become interested in laboratory based simulated gambling tasks for investigating decision making deficits in drug abusers. Several studies have now shown that drug abusers perform poorly in these tasks compared to non abusers. These tasks have the potential to reveal interrelationships of several important factors, such as learning, responsivity to rewards and punishments, personality, and drug abuse profiles, which must be understood to enhance the treatment and prevention of drug abuse. Although useful for examining decision making in the laboratory, the behavior manifested in these tasks is multiply determined, making it impossible to isolate the component processes by simply quantifying the observable behaviors. For example, it is difficult to infer whether poor performance is related to insufficient attention to punishments, altered effects of rewards, inability to learn outcome contingencies, or simply reckless, random behavior in drug abusers. This is a translational research project in which mathematical models previously developed and tested in cognitive psychology will be applied to laboratory gambling tasks currently being used to study decision making in drug abusers. For the proposed project, formal models will be developed to reveal the critical processes that are intertwined and conflated within two gambling tasks. These models will provide a set of theoretically derived measures that describe and quantify basic cognitive processes that underlie the empirical data. We will use these new measures to determine the relative roles of learning, rewards, and punishments in the decision making behavior of drug abusers. Finally, we will determine the relationships between individual differences in drug abusers (i.e., type of drug abused, severity of current abuse, risk-seeking behavior traits) and the cognitive processes that underlie their decision making. The final product of this research will be an integration of our findings on decision making in drug abusers with available neuropsychological models of drug addiction. These theoretical analyses will permit a more direct evaluation of current neuropsychological theories by providing direct estimates of the mediating psychological constructs, thereby eliminating the need to making inferences from observable behavior to neurophysiology. Instead, it will finally be possible to specifically determine the implications of hypothesized neural systems for cognitive and motivational processes involved in drug abuse.

[unreadable] DESCRIPTION (provided by applicant): This is an application for competitive continuation of our research program, which takes a highly integrative approach to understanding drug abuse by using formal decision models to examine the psychopathology of addictions. In our first project period, we used a single stage decision task (Iowa gambling task) to examine individual differences in how learning, motivational, and choice mechanisms interact in the decision making of drug abusers. In the second project period, we will move beyond the single stage decision approach, to develop and empirically test a computational (formal and mathematical) model for the multi-stage self-control decision problem. Multi-stage decision problems more closely resemble the complex decisions drug users face in which they must make a series of decisions that have both proximal outcomes (i.e., getting high, spending money, relief from withdrawal symptoms) as well as possible long term outcomes (i.e., addiction, social and occupational dysfunction). The model addresses three components: Devaluation of immediate reward and delayed punishment; 2) learning of rewards and punishments from trial by trial experience; and, 3) the critical planning process needed to achieve self control in multiple stage decision scenarios. The project has three specific aims. First, we will determine how regular drug users differ from comparison groups on basic evaluative characteristics, including risk aversion, loss aversion, and temporal discounting. Second, we will examine how these evaluative processes interact with learning to guide behavior over time. Third, we will refine and empirically test our comprehensive model for the multiple stage self-control decision problem in regular drug users. The results of our computational model will be examined in the broader context of drug use, demographic, psychosocial, and personality factors that have been linked to drug abuse. The theoretical model from this work will provide a deeper understanding of individual differences in decision processes of drug abusers, will provide a valuable perspective for the prevention and intervention strategies. [unreadable] [unreadable]