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Magnetic ‘blueprints’ show brain at work

U. WARWICK (UK) — Technology developed for fusion plasma may also allow better noninvasive observation of brain activity.

Neuroscientists are limited to external sensing when studying live brains, unless they undertake invasive techniques. One key method researchers use is magnetoencephalography (MEG), in which sensors measure the tiny magnetic fields outside the head that are generated as our brains think.

In order to get a “functional blueprint” of how our brains work, researchers want to use these measurements to pinpoint which different regions of the brain appear to be synchronized with each other as a person does different tasks.


In a University of Warwick study, researchers were interested in how the brain reacts to surprise. Healthy volunteers were asked to listen to a series of “beeps,” some of which were regular and repetitive and some of which were different and out of sequence, and researchers “listened in” to their brain activity using state-of-the-art MEG setup at the Medical Research Council (MRC) Cognition and Brain Sciences Unit at the University of Cambridge.

MEG has great potential as a useful diagnostic tool—it is non-invasive and much more comfortable for patients than other techniques—but the neuromagnetic signal varies rapidly, and the signal to noise ratio is low, which means that interpreting the data can be challenging.

Researchers also face these challenges—extracting signal from noise in observations that can only be made from external sensors—when dealing with magnetically confined plasmas for fusion. Fusion plasma researchers at Warwick have developed methods to deal with data analysis problems similar to those faced by the neuroscientists.

The researchers have now shared these methods and analytical techniques with their neuroscientific colleagues in Cambridge and at Birkbeck, University of London. Together they have been able to carry out new studies that are beginning to provide insights into the brain’s network.

As reported in the Journal of Neurophysiology, they have made the first map of the dynamically changing network of the brain as it deals with the “surprise” of the different sounds.

“The complexity of biological systems like the human brain demands an interdisciplinary approach to data analysis where physicists can combine their quantitative skills with the domain expertise of neuroscientists to achieve greater understanding than either group could achieve alone,” says Ed Bullmore, a professor from the Brain Mapping Unit at Cambridge.

“This study provides exciting new insight into how human brain networks are rapidly reconfigured in response to unpredictable stimuli and also provides a great example of the value added by scientists working together in innovative collaborations to address some of the key challenges of neuroscience.”

When test subjects heard the predictable standard tone the researchers observed that the brain tends to synchronize locally—active connections were mostly between neighboring regions of the brain.

However when the unexpected surprising tones were heard the researchers were able to observe how the human brain dynamically reconfigures its connections—the percentage of long range or global connections used by the brain for communication between widely separated regions increases and this happens near-instantly, in just 80 milliseconds.

It is likely that the brain has evolved to be efficient—to use the least energy possible in performing routine tasks and so only these long-range connections only emerge when they are needed—for example, to assess a surprising event in our environment.

“You never know when knowledge from one field can help out in another. It is very satisfying to find that ideas we have developed to understand remote observations of the ‘space weather’ of the earth’s aurora and magnetic fields, and the dynamics of magnetically confined fusion plasmas—which will one day provide a source of domestic power—can also help us listen in on the workings of the human brain,” says Sandra Chapman, professor of physics, and a lead author of the study with Ruth Nicol, both of Warwick.

The research was supported by GlaxoSmithKline, MRC, and the Engineering and Physical Sciences Research Council.

Additional collaborators include researchers from the Behavioural and Clinical Neuroscience Institute at Cambridge; the GlaxoSmithKline Clinical Unit in Cambridge’s Addenbrooke’s Hospital, Cambridge; and Birkbeck, University of London.

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