In a multi-agent environment, where the outcomes of one's actions change dynamically because they are related to the behavior of other beings, it becomes difficult to make an optimal decision about how to act. Although game theory provides normative solutions for decision making in groups, how such decision-making strategies are altered by experience is poorly understood. These adaptive processes might resemble reinforcement learning algorithms, which provide a general framework for finding optimal strategies in a dynamic environment. Here we investigated the role of prefrontal cortex (PFC) in dynamic decision making in monkeys. As in reinforcement learning, the animal's choice during a competitive game was biased by its choice and reward history, as well as by the strategies of its opponent. Furthermore, neurons in the dorsolateral prefrontal cortex (DLPFC) encoded the animal's past decisions and payoffs, as well as the conjunction between the two, providing signals necessary to update the estimates of expected reward. Thus, PFC might have a key role in optimizing decision-making strategies.

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Objective-Body dysmorphic disorder (BDD), a distressing or impairing preoccupation with an imagined or slight defect in appearance, is an often-severe, understudied disorder. We determined BDD's prevalence and clinical features on a general adult psychiatric inpatient unit. To our knowledge, only one previous prevalence study has been done in this setting. Method-One hundred patients completed 3 self-report measures: the Body Dysmorphic Disorder Questionnaire (BDD-Q), Beck Anxiety Inventory (BAI) and Center for Epidemiologic Studies Depression Scale (CES-D). Those who screened positive for BDD were interviewed to confirm DSM-IV BDD and its clinical features. Charts were reviewed for demographic and clinical information.Results-BDD was diagnosed in 16.0% (95% CI=8.7-23.3%) (n=16) of patients. A high proportion of those with BDD reported that BDD symptoms contributed to suicidality. Patients revealed BDD symptoms to a mean of only 15.1%±33.7% lifetime mental health clinicians; only one (6.3%) reported symptoms to his current inpatient psychiatrist. Most did not disclose their symptoms due to embarrassment. Those with BDD were younger (P=.008) and had higher CES-D scores (P=.008). The two groups did not significantly differ on BAI score, demographic characteristics or discharge diagnoses.Conclusions-BDD is relatively common but underdiagnosed in psychiatric inpatients and is associated with more severe depressive symptoms.

The authors investigated the effects of domain knowledge on online reading among younger and older adults. Individuals were randomly assigned to either a domain-relevant (i.e., high-knowledge) or domain-irrelevant (i.e., low-knowledge) training condition. Two days later, participants read target passages on a computer that drew on information presented in the high-knowledge training session. For both age groups, knowledge improved comprehension and recall and facilitated the processing of topic shifts during reading. In addition, domain knowledge had differential effects on processing across the 2 age groups. Among older (but not younger) readers, domain knowledge increased the time allocated to organization and integration processes (wrap-up) and increased the frequency of knowledge-based inferences during recall. These results suggest that among older readers, domain knowledge engenders an investment of processing resources during reading, which is used to create a more elaborated representation of the situation model.