3.5.16 Default mode and salience networks

Default Mode

The default mode network (DMN) is a network of brain regions that is active when an individual is in a resting or “default” state, such as when they are daydreaming or not actively engaged in a task. The DMN is thought to play a role in a variety of cognitive and emotional processes, including self-reflection, social cognition, and memory.

The DMN is composed of a number of brain regions, including the medial prefrontal cortex, posterior cingulate cortex, and medial temporal lobes. These regions are interconnected and show synchronized activity when an individual is in a resting state (Buckner, 2008).

Research has shown that the DMN is involved in a variety of functions, including self-reflection, social cognition, and memory. For example, studies have shown that the DMN is active when individuals think about themselves or others, when they remember past events, and when they engage in mental simulations of future events.

Abnormalities in the DMN have been observed in a number of neurological and psychiatric disorders, such as Alzheimer’s disease, depression, and schizophrenia. Understanding the neurobiology of DMN may provide insights into the underlying mechanisms of these disorders and inform the development of new treatments.

The DMN is composed of a number of brain regions, including the posterior cingulate cortex (PCC) and medial prefrontal cortex (mPFC). The PCC is a region of the brain that is involved in a number of cognitive and emotional functions. Research has shown that the PCC and mPFC are active when an individual is engaged in introspective or self-referential thoughts, when they are remembering past events, and when they are engaging in mental simulations of future events. The PCC and mPFC are also thought to be involved in the integration of information from different brain regions and in the regulation of attention and behaviour (Gusnard, 2001).

Salience Networks

The salience network is a network of brain regions that are involved in the detection and evaluation of stimuli that are important or relevant to an individual. The salience network is thought to play a key role in the allocation of attention and the regulation of behaviour.

The salience network is composed of a number of brain regions, including the anterior insula and the anterior cingulate cortex. These regions are interconnected and show synchronized activity when an individual is faced with a stimulus that is important or relevant to them. Functional magnetic resonance imaging was used to examine the brain activity of individuals while they performed tasks that required the allocation of attention and the regulation of behaviour. They identified a network of brain regions, including the anterior insula and the anterior cingulate cortex, that showed synchronized activity during these tasks and suggested that this network may play a key role in the detection and evaluation of salient stimuli and the regulation of attention and behaviour (Seeley, 2007).

The salience network is thought to play a role in detecting and evaluating stimuli that are relevant to an individual’s goals, needs, and motivations, and in guiding behaviour accordingly. The salience network is also involved in the regulation of emotions and the processing of social information.

References:

(1) Buckner, R. L., Andrews-Hanna, J. R., & Schacter, D. L. (2008). The brain’s default network: Anatomy, function, and relevance to disease. Annals of the New York Academy of Sciences, 1124(1), 1-38.

(2) Gusnard, D. A., Akbudak, E., Shulman, G. L., & Raichle, M. E. (2001). Medial prefrontal cortex and self-referential mental activity: Relation to a default mode of brain function. Proceedings of the National Academy of Sciences, 98(7), 4259-4264.

(3) Seeley, W. W., Menon, V., Schatzberg, A. F., Keller, J., Glover, G. H., Kenna, H., … & Greicius, M. D. (2007). Dissociable intrinsic connectivity networks for salience processing and executive control. Journal of Neuroscience, 27(9), 2349-2356.