Developing translational animal models for decision making: the Iowa Gambling Task case
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Decision-making under conditions of uncertainity and risk is an essential part of human life. Every day we are required to make complex choices between often conflicting options, of which we can only partially estimate the outcome. Frequently, we are faced with the possibility to choose either for the instant gratification of our needs, which may however result in negative long-term consequences, or for a course of action which may lead to high payoffs in the future: in such cases, refraining from responding to immediate reward cues is essential to engage in behaviours that are adaptive in the long-term. Therefore, it is not surprising that disruptions of decision-making-associated functions in humans have a severe negative impact on the quality of life of the affected individuals, and that such abnormalities have been proposed to represent crucial factors for the development and/or the maintenance of a variety of psychiatric disorders, such as drug addiction, alcohol abuse, and pathological gambling. For the study of long-term efficiency of behaviour and decision-making under ambiguity in humans, the Iowa Gambling Task (IGT) represents one of the most precious experimental tools available to neuroscientists today. In fact, this test manages to incorporate in its design the unpredictability of options' outcomes, the need to weight risks and benefits associated to each available option, and the necessity to exert behavioural control to better perform in the long-term. Additionally, choices made in the IGT are suggested to be the product of both “cold” (explicit--rational) and “hot” (implicit--emotional) option evaluation processes, which compresence commonly characterizes real-life decisions. From its first employment as a test assessing specific cognitive impairments of prefrontal cortex-damaged individuals, the task subsequently found application in the assessment of decision-making deficiencies in a variety of other clinical conditions. The results of such studies have not only helped to better characterize these pathologies, but have in addition contributed to expand significantly our knowledge of neural substrates underlying decision-making, and how their function is compromised in individuals with related deficits. Research on humans however presents a number of limitations, stemming from problems of practical and ethical nature: thus, the development of an animal model of the IGT has been recently considered, and first experimental paradigms have already been proposed for rodents. However, in order to be able to employ such tasks as research tools, a fundamental question that needs be answered beforehand is whether animal IGT paradigms can satisfy face, predictive and construct validity criteria. To date, for each of these translational IGT models the issue of validity has only partially been addressed. Therefore, the scope of this thesis is the evaluation of current animal IGT tasks' efficacy in accurately reproducing every aspect of the original human protocol, and in assessing the same decision-making processes.