When you daydream, or ruminate on something bothersome, or ponder the past, or plan for the future, the part of your brain most engaged is the default mode network, or DMN, which includes part of the prefrontal cortex. Scientists have long hypothesized that changes to DMN dynamics play major roles in certain behaviors, such as those associated with attention deficit-hyperactivity disorder; and diseases, such as Alzheimer’s and Parkinson’s; and conditions such as depression and autism.

But scientists have not fully understood the precise mechanisms that control DMN dynamics. Now, UNC School of Medicine researchers led by Ian Shih, PhD, associate professor of neurology, have experimentally documented the interplay between neurons and brain chemicals across brain regions, leading to alterations in DMN dynamics.

Published in the journal Science Advances, this research in mice provides evidence for how DMN dynamics is altered by activating the locus coeruleus (LC) – a small brain nucleus in the brainstem that releases norepinephrine. It also suggests new targets for treatment to restore DMN function.

Many brain imagers have vast interest in identifying the circuit mechanisms that control large scale brain networks. But how a specific neurotransmitter system alters brain-wide dynamics remains incompletely understood. Our work helps explain how norepinephrine affects brain activity and connectivity, leading to changes in the DMN.
Ian Shih, senior author and director of the Center for Animal MRI (CAMRI) at the UNC Biomedical Research Imagine Center (BRIC).


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