Researchers think the process, roughly akin to tuning multiple walkie-talkies to the same frequency, may help establish clear channels for communication between brain areas that detect sensory stimuli.
"We think the brain not only puts regions that facilitate attention on alert but also makes sure those regions have open lines for calling each other," said first author Amy Daitch, a graduate student researcher.
The results are available in the Proceedings of the National Academy of Sciences.
People who suffer from brain injuries or strokes often have problems paying attention and concentrating.
"Attention deficits in brain injury have been thought of as a loss of the resources needed to concentrate on a task," said senior author Maurizio Corbetta, MD, the Norman J. Stupp Professor of Neurology. "However, this study shows that temporal alignment of responses in different brain areas is also a very important mechanism that contributes to attention and could be impaired by brain injury."
Attention lets people ignore irrelevant sensory stimuli, like a driver disregarding a ringing cell phone, and pay attention to important stimuli, like a deer stepping onto the road in front of the car.
To analyze brain changes linked to attention, the scientists used grids of electrodes temporarily implanted onto the brains of patients with epilepsy. Co-senior author Eric Leuthardt, MD, associate professor of neurosurgery and bioengineering, uses the grids to map for surgical removal of brain tissues that contribute to uncontrollable seizures.
With patient permission, the grids also can allow Leuthardt's lab to study human brain activity at a level of detail unavailable via any other method. Normally, Corbetta and his colleagues investigate attention using various forms of magnetic resonance imaging (MRI), which can detect changes in brain activity that occur every 2 to 3 seconds. But with the grids in place, Corbetta and Leuthardt can study the changes that occur in milliseconds.
Before grid implantation, the scientists scanned the brains of seven epilepsy patients, using MRI to map regions known to contribute to attention. With the grids in place, the researchers monitored brain cells as the patients watched for visual targets, directing their attention to different locations on a computer screen without moving their eyes. When patients saw the targets, they pressed a button to let the scientists know they had seen them.
"We analyzed brain oscillations that reflect fluctuations in excitability of a local brain region; in other words, how difficult or easy it is for a neuron to respond to an input," Daitch said. "If areas of the brain involved in detecting a stimulus are at maximum excitability, you would be much more likely to notice the stimulus."
Excitability regularly rises and falls in the cells that make up a given brain region. But these oscillations normally are not aligned between different brain regions.
The researchers' results showed that as patients directed their attention, the brain regions most important for paying attention to visual stimuli adjusted their excitability cycles, causing them to start hitting the peaks of their cycles at the same time. In regions not involved in attention, the excitability cycles did not change.
"If the cycles of two brain regions are out of alignment, the chances that a signal from one region will get through to another region are reduced," Corbetta said.
Daitch, Corbetta and Leuthardt are investigating whether knowing not just the location, but also the tempo of the task, allows participants to bring the excitability of their brain regions into alignment more rapidly.
Funding from the James S. McDonnell Foundation, the Doris Duke Foundation, the National Institute of Mental Health (R01 MH 71920-09), the National Institute of Health (NIH) (5T32EY013360-10) and the National Science Foundation (NSF EFRI-1137211) supported this research.
Daitch AL, Sharma M, Roland JL, Astafiev SV, Bundy DT, Gaona CM, Snyder AZ, Shulman GL, Leuthardt EC, Corbetta M. Frequency-specific mechanism links human brain networks for spatial attention. Proceedings of the National Academy of Sciences, Nov. 26, 2013.
Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient-care institutions in the nation, currently ranked sixth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.
Michael C. Purdy | EurekAlert!
World first: Massive thrombosis removed during early pregnancy
20.07.2017 | Universitätsspital Bern
Therapy of preterm birth in sight?
19.07.2017 | Universitätsspital Bern
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...
21.07.2017 | Event News
19.07.2017 | Event News
12.07.2017 | Event News
21.07.2017 | Earth Sciences
21.07.2017 | Power and Electrical Engineering
21.07.2017 | Physics and Astronomy