NIH VideoCast - A Default Mode of Brain Function: History of an Evolving Idea

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A Default Mode of Brain Function: History of an Evolving Idea

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Air date:	Wednesday, April 11, 2007, 3:00:00 PM Time displayed is Eastern Time, Washington DC Local
Views:	Total views: 152 * This only includes stats from October 2011 and forward.
Category:	WALS - Wednesday Afternoon Lectures
Runtime:	01:01:44
Closed captioning:	Check box to display CC outside of the video Note: You can drag the captioning window around and resize it
Description:	The concept of a default mode of brain function arose out of a focused need to explain the appearance of activity decreases in functional neuroimaging data when the control state was passive visual fixation or eyes closed resting. The problem was particularly compelling because these activity decreases were remarkably consistent across a wide variety of task conditions. Using PET, we determined that these activity decreases did not arise from activations in the resting state. Hence, their presence implied the existence of a default mode. While the unique constellation of brain areas provoking this analysis has come to be known as the default system, all areas of the brain have a high level of organized default functional activity. Most critically, this work has called attention to the importance of intrinsic functional activity in assessing brain behavior relationships. Marcus E. Raichle is known for his pioneering research in the development and use of an imaging technique called positron emission tomography (PET) to map specific brain areas used in tasks such as seeing, hearing, reading and remembering as well as emotion. Raichle was a member of the team that developed PET at Washington University during the 1970's. The technique, equivalent to tissue autoradiography but done safely in vivo, allows researchers to safely and non-invasively study the living human brain and track and record its function in health and disease. By using PET to monitor blood flow and metabolism in the human brain, Raichle and his collaborators were able to show how the brain responds when a subject is asked to perform tasks as diverse as memorizing words or anticipating an unpleasant experience. In addition, they have mapped areas involved in attention, analyzed chemical receptors in the brain, investigated the physiology of major depression and anxiety and evaluated patients at risk for stroke. Parallel work by Raichle and his colleagues evaluated the relationship between blood flow, metabolism and neuronal activity in the human brain. This work uncovered the fact that blood flow exceeds the brain’s oxygen requirements normally during increased neuronal activity. This fact provides the physiological basis for functional magnetic resonance imaging (fMRI). fMRI is now the primary technique used in mapping the functional architecture of the human brain. Raichle’s most recent work has focused on the brain’s intrinsic activity, that which it is doing when not responding to the momentary demands of environment. Raichle, a neurologist, joined the faculty at Washington University as a research instructor in Neurology and Radiology in 1971. He became a professor of Neurology in 1978, professor of Radiology in 1979, professor of Biomedical Engineering in 1979 and professor of Neurobiology in 1993. He received a bachelor and medical degree from University of Washington in Seattle. He was honored by the University of Washington as their Distinguished Alumnus in 2006. His honors include election to the Institute of Medicine in 1991, to the National Academy of Sciences in 1996 and to the American Academy of Arts and Sciences in 1998. He has also received the Bristol-Myers Squibb Award for Distinguished Achievement in Neuroscience Research and the Grawemeyer Award for Psychology. The NIH Director's Wednesday Afternoon Lecture Series includes weekly scientific talks by some of the top researchers in the biomedical sciences worldwide.

NLM Title:	A default mode of brain function : history of an evolving idea / Marcus E. Raichle.
Author:	Raichle, Marcus E. National Institutes of Health (U.S.)
Publisher:
Abstract:	(CIT): The concept of a default mode of brain function arose out of a focused need to explain the appearance of activity decreases in functional neuroimaging data when the control state was passive visual fixation or eyes closed resting. The problem was particularly compelling because these activity decreases were remarkably consistent across a wide variety of task conditions. Using PET, we determined that these activity decreases did not arise from activations in the resting state. Hence, their presence implied the existence of a default mode. While the unique constellation of brain areas provoking this analysis has come to be known as the default system, all areas of the brain have a high level of organized default functional activity. Most critically, this work has called attention to the importance of intrinsic functional activity in assessing brain behavior relationships. Marcus E. Raichle is known for his pioneering research in the development and use of an imaging technique called positron emission tomography (PET) to map specific brain areas used in tasks such as seeing, hearing, reading and remembering as well as emotion. Raichle was a member of the team that developed PET at Washington University during the 1970's. The technique, equivalent to tissue autoradiography but done safely in vivo, allows researchers to safely and non-invasively study the living human brain and track and record its function in health and disease. By using PET to monitor blood flow and metabolism in the human brain, Raichle and his collaborators were able to show how the brain responds when a subject is asked to perform tasks as diverse as memorizing words or anticipating an unpleasant experience.
Subjects:	Brain Mapping Brain--physiology Magnetic Resonance Imaging Positron-Emission Tomography
Publication Types:	Lecture Webcast
NLM Classification:	WL 300
NLM ID:	101306101
CIT Live ID:	5196
Permanent link:	https://videocast.nih.gov/watch=5196

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