Navigation Links
Stanford-led team validates, extends fMRI research on brain activity
Date:5/16/2010

STANFORD, Calif. Like a motorist who knows that the "check engine" light indicates something important but ill-defined is happening, neuroscientists have relied heavily on an incompletely understood technology called functional magnetic resonance imaging to show them what the brain is doing when people respond to different stimuli. The non-invasive technology offers a window into the physiology of human cognition and emotion, but without a satisfying explanation of how some common fMRI signals are produced the ability of researchers to draw conclusions has been limited.

Now a Stanford University-led team has solved the mystery, and in doing so has discovered a new way to make fMRI signals based on increased blood flow even more useful. Combined with optogenetics (a technology developed at Stanford that employs genes from microbes to allow neurons to be controlled with pulses of light), blood-flow fMRI can now be used to study the brain-wide impact of changes in neural circuitry, such as ones that may underlie many neurological and psychiatric diseases.

The team's research will appear May 16 in the online version of Nature.

A 'BOLD' finding

The study is the first to prove what neurologists could only hope was true: that fMRI signals based on elevated levels of oxygenated blood in specific parts of the brain are caused by an increase in the excitation of specific kinds of brain cells. For example, in the past researchers could only assume that when they showed subjects a picture of someone they knew, stronger fMRI signal in a part of the brain that possibly deals with face recognition was caused by the excitation of neurons, rather than some other factor.

These signal increases are measured using the blood oxygenation level-dependent, or BOLD, technique.

Because researchers have published more than 250,000 papers using or building upon the BOLD technique, clarifying its true meaning is very important, said senior author Karl Deisseroth, MD PhD, associate professor of bioengineering and of psychiatry and behavioral sciences.

"It was often assumed that a positive fMRI BOLD signal can represent increased activity of excitatory neurons, but this was never really known and, in fact, became much more controversial over the years," said Deisseroth. Now, the new study confirms those earlier assumptions.

The key experiment involved turning on genetically engineered excitatory neurons in an experimental group of rats in the presence of blue light delivered via a fiber optic cable. The researchers then anesthetized the rats and looked at their brains with fMRI. They found that exciting these defined neurons with the optogenetic light produced the same kind of signals that researchers see in traditional fMRI BOLD experiments with the same complex patterns and timing. In the control group of rats, which were not genetically altered, no such signals occurred. This showed that true neural excitation indeed produces positive fMRI BOLD signals.

The broader brain

To see what else this new understanding of optogenetically-enhanced fMRI BOLD might yield, the team took the research a few steps further, led by co-first authors Remy Durand, a Stanford bioengineering graduate student, and Jin Hyung Lee, PhD, a University of California-Los Angeles assistant professor and alumna of Deisseroth's lab at Stanford. They found that they could use optogenetics to produce activity in specific kinds of cells in neural circuits, and then read out the far-reaching effects with fMRI BOLD over a substantial distance in the brain.

In one experiment, for example, the team could see how activity they stimulated in the thalamus, a key relay center deep in the brain, could affect circuits stretching into the somatosensory cortex, a surface brain region important in processing sensation.

"We can now ask what the true impact of a cell type is on global activity in the brain of a living mammal," Deisseroth said. "A key to scientific inquiry is developing tools that allow us to intervene and experiment with brain circuits engineering a reversible gain or loss of function rather than simple observation of correlations. This points to new approaches for understanding and treatment."


'/>"/>

Contact: David Orenstein
davidjo@stanford.edu
650-736-2245
Stanford University Medical Center
Source:Eurekalert

Related medicine news :

1. SEO-Peace.com Extends The March Special SEO Special Offers And Revise Many Services
2. Diversinet Extends Reach of Mobile Healthcare Information With New Product Release Targeting Healthcare Organizations
3. Global Medical Staffing Extends Locum Tenens Physician Placement to the Middle East
4. Kardea Nutrition Adds V.P. Sales, Extends Distribution Network
5. McLaren Software Extends the Reach of Asset Document Management Processes
6. Swisslog Extends Materials Transport Product Family for Hospitals by Entering Autonomous Mobile Robot Market with SpeciMinder and RoboCourier
7. ALFA Extends Helping Hand to Haiti
8. Vaccine approach extends life of metastatic prostate cancer patients
9. SecureWorks Extends PCI Approved Scanning Vendor Solutions
10. Angelica Extends Helping Hand to Haitian Hospital
11. Service Corporation International Extends Offer for Keystone North America Inc.
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/27/2016)... ... June 27, 2016 , ... ... payment industry today announced its strategic partnership with Connance, a healthcare industry ... The two companies’ proven, proprietary technology combine to provide health systems, hospitals ...
(Date:6/26/2016)... ... June 26, 2016 , ... On June 10-11, 2016, A Forever ... Cereal Festival and World’s Longest Breakfast Table in Battle Creek, MI, where the rehabilitation ... as home to some of the world’s leading providers of cereal and other breakfast ...
(Date:6/26/2016)... ... June 26, 2016 , ... Many women are confused ... endometriosis. These women need a treatment plan to not only alleviate symptoms and ... help for preservation of fertility and ultimately achieving a pregnancy. The specialists at ...
(Date:6/25/2016)... ... 2016 , ... "With 30 hand-drawn hand gesture animations, FCPX users can easily ... of Pixel Film Studios. , ProHand Cartoon’s package transforms over 1,300 hand-drawn pictures ... . Simply select a ProHand generator and drag it above media or text in ...
(Date:6/25/2016)... ... ... On Friday, June 10, Van Mitchell, Secretary of the Maryland Department of Health and ... their exemplary accomplishments in worksite health promotion. , The Wellness at Work Awards took ... the BWI Marriott in Linthicum Heights. iHire was one of 42 businesses to receive ...
Breaking Medicine News(10 mins):
(Date:6/23/2016)... Research and Markets has announced the ... to 2022" report to their offering. ... patients with kidney failure, it replaces the function of kidneys ... blood and thus the treatment helps to keep the patient ... Increasing number of ESRD patients & substantial ...
(Date:6/23/2016)... DUBLIN , June 23, 2016 ... "Global MEMS Devices Medical Market Analysis 2016 - Forecast to ... The report contains up to date financial ... reliable analysis. Assessment of major trends with potential impact on ... dive analysis of market segmentation which comprises of sub markets, ...
(Date:6/23/2016)... INDIANAPOLIS , June 23, 2016 If ... Leaders Scholarship is any indication, the future is in ... at www.diabetesscholars.org by the Diabetes Scholars Foundation ... the way of academic and community service excellence. ... since 2012, and continues to advocate for people with ...
Breaking Medicine Technology: