Brain lives at "edge of chaos"
March 18, 2009
Courtesy Public Library of Science
and World Science staff
U.K. researchers are offering new evidence that the human brain lives
"on the edge of chaos," at a critical transition point between
randomness and order.
The study, published March 20 in the research journal PLoS Computational
Biology, provides experimental data on an idea previously fraught
with theoretical speculation.
Scientists have identified a phenomenon they call self-organized
criticalitywhere systems spontaneously organize themselves to
operate at the borderline between order and chaosin many different
physical systems, including avalanches, forest fires, earthquakes, and
heart rhythms.
According to the study, by a team from the University of Cambridge, the
Medical Research Council Cognition & Brain Sciences Unit, and the
GlaxoSmithKline Clinical Unit Cambridge, human brain network
dynamics have something important in common with some superficially
very different systems in nature.
Computational networks showing these characteristics have also been
shown to have the best memory and information-processing capacity,
researchers say: critical systems can respond quickly and extensively
to small changes in their inputs.
"Due to these characteristics, self-organized criticality is
intuitively attractive as a model for brain functions such as
perception and action, because it would allow us to switch quickly
between mental states in order to respond to changing environmental
conditions," said co-author Manfred Kitzbichler of Cambridge.
The researchers used brain imaging techniques to measure dynamic
changes in the synchronization of activity between different regions
of the functional network in the human brain. They also investigated
the synchronization of activity in computational models, and found
that the "dynamic profile" they had identified in the brain was exactly
reflected in the models.
"A natural next question we plan to address in future research will be:
How do measures of critical dynamics relate to cognitive performance
or neuropsychiatric disorders and their treatments?" said Kitzbichler.
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