February 14, 2012
Welcome to what could become a regular feature on the Emory Health Now blog: explaining a word or phrase that is connected with research going on at Emory.
What is the default mode network?
This is a concept that grew out of brain imaging studies, using techniques such as functional magnetic resonance imaging. The default mode network consists of regions of the brain that are active when someone is not doing anything in particular, especially something requiring focused attention. More fancifully: it’s what daydreaming looks like.
Researchers at Emory and elsewhere have been looking at whether the DMN’s activity and its links to other areas of the brain are changed in disorders such as schizophrenia, autism, depression and post-traumatic stress disorder.
For example, Xiaoping Hu, director of Emory’s Biomedical Imaging Technology Center, and his colleagues have investigated how the default mode network’s activity is modified in individuals with prenatal alcohol exposure and prenatal cocaine exposure. They also have probed how the DMN’s activity is shut down by anesthesia.
At the Atlanta Veterans Affairs Medical Center, Erica Duncan and her colleagues have examined the DMN in people with schizophrenia. They found (as have other groups) that individuals with schizophrenia appear to have difficulty shutting down the DMN and focusing on a task, as well as having a different pattern of connections within the DMN.
The DMN is made up of several regions of the brain, most prominently the posterior cingulate cortex (PCC) and medial prefrontal cortex (MPFC). Other regions such as the inferior parietal lobule, lateral temporal cortex, and hippocampal formation including parahippocampus are also considered part of the DMN. Note: these regions can also be engaged in other tasks besides daydreaming or introspection.