User:Thetmn/sandbox

Psychiatric and neurological disorders can be characterized by connectivity within and between large-scale brain networks. These networks are important to study because they can provide a better understanding of the impact of these disorders, more so than studying one brain region, as recent research has shown that multiple brain regions are involved in these disorders. Understanding the disruptions in these networks may provide important insights into interventions for treating these disorders. Recent work suggests that at least three large-scale brain networks are important in psychopathology : •	Central Executive Network •	Default mode network •	Salience Network

Central Executive Network:  The central executive network is made up of fronto-parietal regions, including dorsolateral prefrontal cortex and lateral posterior parietal cortex. Studies have shown that this network is crucially involved in maintaining and using information in working memory, problem solving, and decision making. Deficiencies in this network are common in most major psychiatric and neurological disorders, including depression. Because this network is crucial for everyday life activities, those who are depressed can show impairment in basic activities like test taking and being decisive.

Default Mode Network: The default mode network includes hubs in the prefrontal cortex and posterior cingulate, with other prominent regions of the network in the medial temporal lobe and angular gyrus. The default mode network is usually active during mind-wandering and thinking about social situations. In contrast, during specific tasks probed in cognitive science (for example, simple attention tasks), the default network is often deactivated. Research has shown that regions in the default mode network (including medial prefrontal cortex and posterior cingulate) show greater activity when depressed participants ruminate (that is, when they engage in repetitive self-focused thinking) than when typical, healthy participants ruminate. Individuals suffering from major depression also show increased connectivity between the default mode network and the subgenual cingulate and the adjoining ventromedial prefrontal cortex in comparison to healthy individuals, individuals suffering from dementia, and autistic individuals. Numerous studies suggest that the subgenual cingulate plays an important role in the dysfunction that characterizes major depression. The increased activation in the default mode network during rumination and the atypical connectivity between core default mode regions and the subgenual cingulate may underlie the tendency for depressed individual to get “stuck” in the negative, self-focused thoughts that often characterize depression. However, further research is needed to gain a precise understanding of how these network interactions map to specific symptoms of depression. Salience Network: The salience network is a cingulate-frontal operculum network that includes core nodes in the anterior cingulate and anterior insula. Salience refers to the process by which highly processed sensory information is integrated with information from the body to guide attention and action. Individuals who have a tendency to experience negative emotional states (scoring high on measures of neuroticism) show an increase in the right anterior insula during decision-making, even if the decision has already been made. This atypically high activity in the right anterior insula is thought to contribute to the experience of negative and worrisome feelings. In major depressive disorder, anxiety is often a part of the emotional state that characterizes depression.