Characterization of the Motivational Deficit in Schizophrenia and Depression

Depression, Schizophrenia

Schizophrenia, Negative symptoms, Lack of motivation, Cognitive characterization, Computational psychiatry, Depression

This research focuses on disorders of motivation, responsible for a disability that patients experience daily. It is a disorder that affects behavior, especially social. Mechanisms, which result in these disorders, are poorly understood. This ignorance is responsible for the lack of effective therapy. The investigators realize this work in order to better understand the motivational deficits. The objective of the study is to characterize the cognitive mechanisms of motivational deficits in schizophrenia and depression. To answer the question posed in the research, it is planned to include 35 people with schizophrenia, 35 people with depression and 70 heathy volunteers in the Hospital of Sainte-Anne .

The investigator goal is to develop a neuropsychological battery to characterize the different aspects of motivation: energizing action, ability to use the clues to assign value, ability to anticipate a reward delayed in time, and finally learning by trial / error based rewards. In addition, the investigators systematically compare the effect of rewards and punishments (losses) in these spots. Such a systematic approach should better understand the nature of disrupted in schizophrenia process. It should also highlight the differential effects of treatment, including the effects of conventional antipsychotics versus atypical antipsychotics, but also the benefits of cognitive remediation. In the depression: The motivational deficit is at the heart of the depressive symptomatology. Our objective is to characterize the motivational processes altered in the depression thanks to the same neuropsychological battery. Furthermore, this clinical dimension could influence the answer to the antidepressant treatment. A better characterization of the motivational deficit would allow to adapt at best the pharmacological treatments used in the depression, in particular by targeting the dopaminergic way, involved in the control of the motivation. The investigators will recruit 35 patients and 35 control subjects in both populations. The investigators will make them pass a battery of motivational tests described above on three half-days: \- Force task: This task tests the energization process, that is to say the ability to activate an action in proportion to what is involved. It consists of two sessions of 60 trials, which are offset through six levels of monetary issue (1, 20, 50 cents, 1, 5, 20 euros), and lasts about 30 minutes. On each trial, patients must tighten the grip dynamometer in order to earn a reward proportional to both the level of monetary issue and the peak forces occurs, or avoid a financial loss of a magnitude equal. The award of this task will be made in subliminal conditions and in supraliminal, and in condition of mental effort with the use of a stroop test instead of the dynamometer. \- Preference task: This task tests the integrity of the brain recovery system. It includes three subtests quotes 24 awards, 24 penalties and 24 efforts, and three subtests of binary choices with 48 trials each, and lasts about 30 minutes. Patients should note how various awards seem pleasant, how various punishments seem unpleasant, or how various efforts seem harsh. Registration vegetative markers (heart rate) compares the implied valuations for explicit assessments (notes), and thus to estimate the accuracy of introspection. \- Discount and effort task: These tasks are used to estimate the parameters of time counting efforts and punishments. In the task of counting time effort, patients must choose between making a small reward associated with a low time or earn a greater reward associated with a significant delay. In the task of temporal punishments count, patients must choose between experience low punishment in a short time, or suffer a greater punishment in a larger delay. These tasks can capture a form of apathy characterized by an exaggeration of fatigue or pain early. \- Learning task: It can test the overall learning abilities and specific sensitivities learning by positive and negative reinforcement. It consists of two sessions, each with 60 binary choices (24 associated with rewards, punishments associated with 24, 12 associated with neutral events), for a period of about 20 minutes. The second session will be provided in counterfactual condition.

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