, 2007; Gradin et al., 2011). It has been proposed that insufficient suppression
of the default network or its hyperactivity might be related to positive symptoms of schizophrenia, such as hallucination and paranoia (Buckner et al., 2008; Anticevic et al., 2012). For example, the amount of task-related suppression is reduced in some areas of the default network (Whitfield-Gabrieli et al., 2009; Selleckchem ABT 888 Anticevic et al., 2013). Given a large overlap between the default network and the brain areas involved in social cognition, hyperactivity, or any abnormal activity patterns in the default network might also underlie impairments in social functions among patients with schizophrenia (Couture et al., 2006). In addition, psychotic symptoms
of schizophrenia tend to emerge after early adulthood, often many years after impaired cognitive functions can be detected (Cornblatt et al., 1999; Cannon et al., 2000). This is consistent with the hypothesis that clinical symptoms of schizophrenia arise from malfunctions ATR inhibitor of the prefrontal cortex and default network, since similar to the extended developmental trajectory of the prefrontal cortex (Lewis, 2012), the functional connectivity of the default network continues to increase during adolescence (Fair et al., 2008). Therefore, it would be important to test whether subjects at risk for schizophrenia are impaired in tasks that require model-based reinforcement learning. Depression and anxiety disorder are both examples of internalizing disorders, namely,
they are largely characterized by disturbances in mood and emotion (Kovacs the and Devlin, 1998; Krueger, 1999). These two conditions show a high level of comorbidity and are accompanied by poor concentration and negative mood states, such as sadness and anger (Mineka et al., 1998). Nevertheless, there are some important differences. Overall, symptoms of anxiety are appropriate for preparing the affected individuals for impending danger, whereas depression might inhibit previously unsuccessful actions and facilitate more reflective cognitive processes (Oatley and Johnson-Laird, 1987). Physiological arousal is an important feature of anxiety, whereas anhedonia and reduced positive emotions occur in depression (Mineka et al., 1998). Both depression and anxiety disorder tend to introduce systematic biases in attentional and mnemonic processes as well as decision making (Mineka et al., 1998; Paulus and Yu, 2012). In particular, individuals with anxiety disorders become hypersensitive to potentially threatening cues without obvious memory bias. In contrast, depressed individuals show a bias to remember negative events (Matt et al., 1992), and to ruminate excessively (Nolen-Hoeksema, 2000). The possible neural changes responsible for the symptoms of these two mood disorders have been extensively studied, and some candidate brain systems have been identified.