Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Modeling the restless brain

05.06.2007
IU neuroscientists tie network structure to brain's spontaneous activity

Indiana University neuroscientists Olaf Sporns and Christopher Honey find the 98 percent of brain activity that other researchers consider just background noise to be fascinating and important.

Brains are always active, even when people are at rest. In this "resting state," waves of neural activity ripple through the brain, creating fluctuating and ever-changing patterns. Sporns and Honey's work on modeling this brain activity sheds new light on how and when these mysterious fluctuations occur and offers insights into what the brain does while idle.

"Some people see the brain in terms of inputs and outputs, like a computer. If you provide an input, you'll get a particular output," said Honey, a doctoral student in IU Bloomington's Department of Psychological and Brain Sciences. "We take a different view. We believe that even in the absence of an external stimulus, there are very important processes going on in the brain which affect the stimulus-responses that the brain will produce. We believe that ongoing spontaneous activity should be studied in itself. Other researchers consider this to be unimportant 'noise' that should be filtered out."

Honey and Sporns, associate professor in the Department of Psychological and Brain Sciences, took a close look at the spontaneous activity of the brain at rest. With their computational approach -- which involved creating a large-scale computer model of the brain of a macaque monkey -- they demonstrated that the shape and pattern of the fluctuations are determined by the brain's wiring diagram, its neuroanatomy.

Their model also can show how slow 5- to 10-second fluctuations of activity emerge naturally from much faster, chaotic neural interactions that typically last only a few milliseconds.

"Our model suggests that the cortical resting state is not time-invariant, but instead contains rich and interrelated temporal structure at multiple time scales that is shaped by the underlying structural topology," Sporns and Honey wrote in an article appearing this week in the Proceedings of the National Academy of Sciences early edition online.

The article, which will be available at http://www.pnas.org/cgi/doi/10.1073/pnas.0701519104, includes a link to a movie that visualizes what spontaneous fluctuations in the monkey's brain would look like. Coauthors of the article are Rolf Kötter, a neuroanatomist at Radboud University in Nijmegen in the Netherlands, and Michael Breakspear, a cognitive neuroscientist at the University of New South Wales in Australia.

When a person reads a book or talks with a friend, task-related neural activity occurs in different regions of the brain, but this activity only accounts for around 2 to 5 percent of the total activity of the brain. Fluctuations of similar magnitude -- the ones studied by Sporns and Honey -- occur when a person is at rest, doing nothing.

The nature of these "resting state fluctuations" is an active topic of research in cognitive neuroscience, with their mysterious origin prompting one prominent researcher to label them the "brain's dark energy," Sporns said. As yet, no one knows why these fluctuations occur or what their function might be.

Sporns and Honey suggest that a closer look at brain structure might provide a new perspective.

Despite the huge amount of work being done by neuroscientists, relatively little is known about how the human brain is structured -- how, for example the hundreds (the number is unknown) of regions in the human brain are connected. The computer model created by Sporns and Honey suggests that this very pattern of connectivity is crucial to generating and shaping brain activity in the resting and active brain.

Empirical work on the human brain is challenging due to the fact that the brain's intricacies cannot simply be manipulated and observed. Sporns and Honey compare studying the brain to studying other complex systems such as cellular metabolism, the economy or global climate change. Models must be used to test theories and generate new insights into how the system works as a whole.

And while technologies such as functional MRI allow scientists to measure some kinds of neural connectivity, neuroinformatics approaches, which use extensive anatomical and physiological data sets to describe the macacque's brain, allowed Sporns and Honey to collect data on all the activity that occurred during their simulations.

Sporns said he wants to create a similar large-scale computer model of the human brain that will allow them to study larger networks and connectivity, once the necessary data sets of how human neural networks are structured are available.

A computational model of the human brain would help researchers better understand where the observed resting state fluctuations come from. It also would let them tie neural activity to cognitive and behavioral performance and ask questions about differences in the brains of individual persons.

Sporns said this research could lead to clinical applications, offering new diagnostic tools for brain disorders such as Alzheimer's disease that are known to affect the brain's connections. It also could help explain why humans do not think alike.

"If fluctuations in brain activity are shaped by anatomy," Sporns said, "then individual differences in the way people think and what they think about could be rooted in differences in the way their brains are connected."

Olaf Sporns | EurekAlert!
Further information:
http://www.indiana.edu

More articles from Health and Medicine:

nachricht One gene closer to regenerative therapy for muscular disorders
01.06.2017 | Cincinnati Children's Hospital Medical Center

nachricht The gut microbiota plays a key role in treatment with classic diabetes medication
01.06.2017 | University of Gothenburg

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>