Validating maps of the brain's resting state

June 19, 2013, Vanderbilt University
An fMRI map of a resting state network that shows the connections between the sub-regions of the thalamus with other parts of the brain. The different colors represent the overall functional association of the sub-regions with other areas of the brain. Credit: Arabinda Mishra, Vanderbilt Institute of Imaging Science

Kick back and shut your eyes. Now stop thinking. You have just put your brain into what neuroscientists call its resting state. What the brain is doing when an individual is not focused on the outside world has become the focus of considerable research in recent years. One of the potential benefits of these studies could be definitive diagnoses of mental health disorders ranging from bipolar to post-traumatic stress disorders.

For the last decade, neuroscientists have been using the non-invasive brain- functional called or fMRI to examine in human and animal brains in the resting state in order to figure out how different are connected and to identify the changes that occur in neurological and psychiatric diseases. For example, there are indications that Alzheimer's may be associated with decreased connectivity; depression with increased connectivity; epilepsy with disruptions in connectivity and Parkinson's with alterations in connectivity.

A team of psychologists and imaging scientists at Vanderbilt has collaborated on a study that provides important corroboration of the validity of these studies by examining the relationship of the fMRI maps of resting state brain's networks with the brain's underlying anatomical and neurological structure. The study is published in the June 19 issue of the journal Neuron.

"Previous studies have suggested that resting state connectivity shown in brain scans is anchored by anatomical connectivity," said co-senior author Anna Roe, professor of psychology. "But our study has confirmed this relationship at the single neuron level for the first time."

That is important because fMRI doesn't measure brain activity directly. It does so by measuring changes in blood-oxygen levels in different areas. The technique relies on the observation that when activity in an area of the brain increases, blood-oxygen levels in that region rise, which modulates the MRI signal. Neuroscientists have taken this a step further by assuming that different areas in the brain are connected if they show synchronized variations while the brain is in a resting state.

"This is an important validation," said co-senior author John Gore, director of the Institute of Imaging Science at Vanderbilt and Hertha Ramsey Cress University Professor of Radiology and Radiological Sciences and Biomedical Engineering. "There has always been a sense of unease that we might be interpreting something incorrectly but this gives us confidence that resting state variations can be interpreted in a meaningful way and encourages us to continue the research we have been doing for a number of years. Resting state fMRI provides a uniquely powerful, non-invasive technology to look at the circuits in the human brain."

To examine the relationship between fMRI scans, patterns of neuronal activity and anatomical structure of the brain, the researchers examined the region of the parietal lobe of squirrel monkeys devoted to monitoring touch sensations. Specifically, they looked at an area linked to the hand that consists of a series of adjacent areas each devoted to a different finger.

Using one of the strongest MRI machines available, with a field strength three to six times that of typical clinical scanners, the researchers produced that resolved millimeter-scale networks for the first time.

To compare these patterns to the actual electrical activity in the brains, the researchers inserted electrodes capable of recording the firing patterns of individual neurons. In addition, they used optical techniques to trace the anatomical connections between the neurons throughout the region.

"With all three techniques, we found the same pattern of connectivity. Connections coming from other areas in the brain tend to link to individual digits while connections that originate within the area tend to link to multiple digits," said Roe. "Our results demonstrate that images of the resting state brain accurately reflect the 's anatomical and functional connectivity down to an extremely fine scale."

Explore further: Epileptic seizures can propagate using functional brain networks

Related Stories

Epileptic seizures can propagate using functional brain networks

April 2, 2013
The seizures that affect people with temporal-lobe epilepsy usually start in a region of the brain called the hippocampus. But they are often able to involve other areas outside the temporal lobe, propagating via anatomically ...

Has evolution given humans unique brain structures?

February 22, 2013
Humans have at least two functional networks in their cerebral cortex not found in rhesus monkeys. This means that new brain networks were likely added in the course of evolution from primate ancestor to human. These findings, ...

Brain research provides clues to what makes people think and behave differently

February 6, 2013
Differences in the physical connections of the brain are at the root of what make people think and behave differently from one another. Researchers reporting in the February 6 issue of the Cell Press journal Neuron shed new ...

Rehabilitation based on brain-computer interfaces could be superior to robot-assisted programs, research finds

June 5, 2013
Changes in the pattern of connections in the resting brain predict the extent to which stroke patients will recover following rehabilitation, according to new research led by Cuntai Guan of the A*STAR Institute for Infocomm ...

Imaging technique could help traumatic brain injury patients: Mapping technology used to predict long-term effects

May 9, 2013
(Medical Xpress)—A new application of an existing medical imaging technology could help predict long-term damage in patients with traumatic brain injury, according to a recent UC San Francisco study.

Post-stroke depression linked to functional brain impairment

June 5, 2012
Researchers studying stroke patients have found a strong association between impairments in a network of the brain involved in emotional regulation and the severity of post-stroke depression. Results of the study are published ...

Recommended for you

The neurobiology of fruit fly courtship helps illuminates human disorders of motivation

July 13, 2018
Two fruit flies meet in an acrylic mating chamber and check each other out. It's the insect version of speed dating for science.

Fragile X: New drug strategy corrects behavior/biochemical measures in mouse model

July 13, 2018
Research in mice shows that a pharmacological strategy can alleviate multiple behavioral and cellular deficiencies in a mouse model of fragile X syndrome (FXS), the most common inherited form of intellectual disability and ...

Chemicals associated with oxidative stress may be essential to development

July 12, 2018
Some level of molecules linked to oxidative stress may be essential to health and development, according to new animal studies.

The VIPs of the nervous system—a tiny population of neurons holds a master key to the body's clock

July 12, 2018
Travel by airplane has opened the door to experiencing different cultures and exploring natural wonders. That is, if you can get past the jet lag.

Novel therapy delays muscle atrophy in Lou Gehrig's disease model

July 12, 2018
Supplementing a single protein found in the spinal cord could help prevent symptoms of Lou Gehrig's disease, according to a new study out of Case Western Reserve University School of Medicine. Researchers found high levels ...

Why are neuron axons long and spindly? Study shows they're optimizing signaling efficiency

July 11, 2018
A team of bioengineers at UC San Diego has answered a question that has long puzzled neuroscientists, and may hold a key to better understanding the complexities of neurological disorders: Why are axons, the spindly arms ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.