Neurology & Neurological Surgery
Professor Marcus E. Raichle, M.D.*
Radiology
(Neurology)
Anatomy & Neurobiology
Our work uses short-lived (i.e., 2-110 minute half-life)
cyclotron-produced, positron-emitting radionuclides with positron emission
tomography (PET) and functional Magnetic Resonance Imaging (f MRI) for the in
vivo study of the central nervous system of humans and non-human primates.
The research can be divided into two general categories: methods development and
applications. In the area of methods development, we are concerned with the
development and testing of mathematical models of blood flow, metabolism and
pharmacology in in vivo systems. This work has ranged from strategies for the
measurement of blood flow, blood volume, oxygen consumption, tissue pH and
glucose utilization to receptor pharmacology. Most recently, we have been
involved in investigations of image analysis strategies, including image
averaging techniques, response localization in functional images and statistical
analysis techniques. Applications involve studies in normal subjects using PET
and fMRI to determine systems within the normal human brain concerned with
specific cognitive and emotional functions. We are studying patients with
psychiatric diseases such as depression and anxiety to determine the systems
(language, memory, attention) responsible for the disease and the response of
these systems to treatment.
MacLeod A-M, Buckner RL, Miezin FM, Petersen SE, Raichle ME. Right prefrontal
cortex activation during semantic monitoring. NeuroImage 1998 7:41-48.
Ojemann JG, Neil JM, MacLeod A-M, et al. Increased functional vascular response
in the region of a glioma. J Cereb Blood Flow Metab 1998 18:148-153.
Yablonskiy DA, Neil JJ, Raichle ME, Ackerman JH. Homonuclear J coupling effects
in volume localized NMR spectroscopy: pitfalls and solutions. Magn Reson Med
1998 39:169-178.
Drevets WC, Price JL, Simpson JR Jr, et al. Subgenual prefrontal cortex
abnormalities in mood disorders. Nature 1997 386:824-827.
Ojemann JG, Akbudak E, Snyder AZ, et al. Anatomic localization and quantitative
analysis of gradient refocused echo-planar fMRI susceptibility artifacts.
NeuroImage 1997 6:156-167.
*=member, Division of Biology & Biomedical Sciences
Marcus E. Raichle, M.D.,
will receive the 1998 Karl Spencer Lashley Award from the American Philosophical
Society at a Nov. 13 dinner at the society's annual meeting in Philadelphia.
Raichle and colleague Michael I. Posner, Ph.D., a former Washington University
faculty member now at the University of Oregon, will share the award for their
contributions to brain imaging.
Raichle, co-director of
the Division of Radiological Sciences and professor of radiology, neurology and
neurobiology, and Posner, professor of psychology at Oregon, are being
recognized for pioneering the use of noninvasive imaging to understand brain
function. They are co-authors of a Scientific American volume about this topic
called "Images of Mind," which received the 1996 William James Book
Award from the American Psychological Association.
The American
Philosophical Society, the oldest learned society in the United States, was
established by Benjamin Franklin in 1743 to promote scholarly and scientific
inquiry. Elected members have included John J. Audubon, Robert Frost and Charles
Darwin, and more than 200 Nobel Prize winners have been members since 1901.
A member of the National
Academy of Sciences, Raichle and colleagues pioneered the use of positron
emission tomography (PET) imaging to map specific brain areas used in tasks such
as seeing, hearing, speaking and remembering. Posner, one of the world's leading
cognitive psychologists, added his skills to the work when he joined this effort
in 1985. PET itself was developed at Washington University during the 1970s to
allow researchers to study the living human brain noninvasively and to track and
record its function.
Working with colleagues
at the University, Raichle and Posner helped develop many of the basic
experimental strategies used worldwide to map the human brain with PET and, more
recently, with magnetic resonance imaging. These techniques are providing an
increasingly sophisticated view of how the normal human brain functions. Maps of
brain chemistry and metabolism complement these maps of brain function. In
combination, such maps not only tell us how the brain and our behaviors are
related, but also how diseases such as stroke, depression, anxiety and
Parkinson's disease affect brain function.
Raichle joined the
University faculty as a research instructor in neurology in 1971. He received a
bachelor's degree from the University of Washington in Seattle in 1960 and a
medical degree from the same institution in 1964.
References:
Effects of lexicality,
frequency, and spelling-to-sound consistency on the functional anatomy of
reading. 1999.
Fiez JA, Balota DA, Raichle ME, Petersen SE
Department of Psychology and Neuroscience, University of Pittsburgh,
Pennsylvania 15260, USA. fiez+@pitt.edu
Functional neuroimaging was used to investigate three factors that affect
reading performance: first, whether a stimulus is a word or pronounceable
non-word (lexicality), second, how often a word is encountered (frequency), and
third, whether the pronunciation has a predictable spelling-to-sound
correspondence (consistency). Comparisons between word naming (reading) and
visual fixation scans revealed stimulus-related activation differences in seven
regions. A left frontal region showed effects of consistency and lexicality,
indicating a role in orthographic to phonological transformation. Motor cortex
showed an effect of consistency bilaterally, suggesting that motoric processes
beyond high-level representations of word phonology influence reading
performance. Implications for the integration of these results into theoretical
models of word reading are discussed.
Effects of lexicality,
frequency, and spelling-to-sound consistency on the functional anatomy of
reading.
Fiez JA, Balota DA, Raichle ME, Petersen SE
Department of Psychology and Neuroscience, University of Pittsburgh,
Pennsylvania 15260, USA. fiez+@pitt.edu
Functional neuroimaging was used to investigate three factors that affect
reading performance: first, whether a stimulus is a word or pronounceable
non-word (lexicality), second, how often a word is encountered (frequency), and
third, whether the pronunciation has a predictable spelling-to-sound
correspondence (consistency). Comparisons between word naming (reading) and
visual fixation scans revealed stimulus-related activation differences in seven
regions. A left frontal region showed effects of consistency and lexicality,
indicating a role in orthographic to phonological transformation. Motor cortex
showed an effect of consistency bilaterally, suggesting that motoric processes
beyond high-level representations of word phonology influence reading
performance. Implications for the integration of these results into theoretical
models of word reading are discussed.
Food for thought:
altitude versus normal brain function. 1997
Raichle ME
Washington University School of Medicine, St Louis, Missouri 63110, USA.
This paper presents a general overview of the implementation of cognitive skills
in the normal human brain as viewed from a modern functional brain imaging
perspective. It is hoped that information of this type will assist eventually in
developing a more informed neurobiological basis for the understanding of the
cognitive impairments that occur all too frequently during sojourns to extreme
altitude.
Behind the scenes of
functional brain imaging: a historical and physiological perspective. 1998.
Raichle ME
Washington University School of Medicine, 4525 Scott Avenue, St. Louis, MO
63110, USA.
At the forefront of cognitive neuroscience research in normal humans are the new
techniques of functional brain imaging: positron emission tomography and
magnetic resonance imaging. The signal used by positron emission tomography is
based on the fact that changes in the cellular activity of the brain of normal,
awake humans and laboratory animals are accompanied almost invariably by changes
in local blood flow. This robust, empirical relationship has fascinated
scientists for well over a hundred years. Because the changes in blood flow are
accompanied by lesser changes in oxygen consumption, local changes in brain
oxygen content occur at the sites of activation and provide the basis for the
signal used by magnetic resonance imaging. The biological basis for these
signals is now an area of intense research stimulated by the interest in these
tools for cognitive neuroscience research.
Imaging the mind.
1998
Raichle ME
Washington University School of Medicine, St. Louis, MO 63110, USA.
At the forefront of cognitive neuroscience research in normal humans are the new
techniques of functional brain imaging: positron emission tomography (PET) and,
more recently, magnetic resonance imaging (MRI). The signal used by PET is based
on the fact that changes in the cellular activity of the brain of normal, awake
humans and laboratory animals are accompanied almost invariably by changes in
local blood flow. This robust, empirical relationship has fascinated scientists
for well over a hundred years. PET provided a level of precision in the
measurement of blood flow that opened up the modern era of functional human
brain mapping. Further, the discovery with PET that these changes in blood flow
are unaccompanied by quantitatively similar changes in oxygen consumption has
paved the way for the explosive rise in the use of MRI in functional brain
imaging. The remarkable success of this enterprise is a fitting tribute to men
like Michel Ter-Pogossian. He pioneered the use of positron emitting
radionuclides in biology and medicine when most had abandoned them in favor of
more conventional nuclear medicine radionuclides. Importantly, also, he welcomed
into his laboratory young scientists with a broad range of talents, many of whom
subsequently became leaders in imaging the mind in research centers throughout
the world.