What is the basis of symptoms and malfunctioning brain circuits?

The different symptom domains of schizophrenia are hypothesized to be regulated by unique brain regions. Positive symptoms of schizophrenia are hypothetically modulated by malfunctioning mesolimbic circuits, while negative symptoms are hypothetically linked to malfunctioning mesocortical circuits and may also involve mesolimbic regions such as the nucleus accumbens, which is part of the brain’s reward circuitry and thus plays a role in motivation. The nucleus accumbens may also be involved in the increased rate of substance use and abuse seen in patients with schizophrenia. Affective symptoms are associated with the ventromedial prefrontal cortex, while aggressive symptoms (related to impulse control) are associated with abnormal information processing in the orbitofrontal cortex and amygdala. Cognitive symptoms are associated with problematic information processing in the dorsolateral prefrontal cortex. Although there is overlap in function among different brain regions, understanding which brain regions may be predominantly involved in specific symptoms can aid in customization of treatment to the particular symptom profile of each individual patient with schizophrenia.