Navigation Links
Brain's 'radio stations' have much to tell scientists

Like listeners adjusting a high-tech radio, scientists at Washington University School of Medicine in St. Louis have tuned in to precise frequencies of brain activity to unleash new insights into how the brain works.

"Analysis of brain function normally focuses on where brain activity happens and when," says Eric C. Leuthardt, MD. "What we've found is that the wavelength of the activity provides a third major branch of understanding brain physiology."

Researchers used electrocorticography, a technique for monitoring the brain with a grid of electrodes temporarily implanted directly on the brain's surface. Clinically, Leuthardt and other neurosurgeons use this approach to identify the source of persistent, medication-resistant seizures in patients and to map those regions for surgical removal. With the patient's permission, scientists can also use the electrode grid to experimentally monitor a much larger spectrum of brain activity than they can via conventional brainwave monitoring.

Scientists normally measure brainwaves with a process called electroencephalography (EEG), which places electrodes on the scalp.

Brainwaves are produced by many neurons firing at the same time; how often that firing occurs determines the activity's frequency or wavelength, which is measured in hertz, or cycles per second. Neurologists have used EEG to monitor consciousness in patients with traumatic injuries, and in studies of epilepsy and sleep.

In contrast to EEG, electrocorticography records brainwave data directly from the brain's surface.

"We get better signals and can much more precisely determine where those signals come from, down to about one centimeter," Leuthardt, assistant professor of neurosurgery, of neurobiology and of biomedical engineering, says. "Also, EEG can only monitor frequencies up to 40 hertz, but with electrocorticography we can monitor activity up to 500 hertz. That really gives us a unique opportunity to study the complete physiology of brain activity."

Leuthardt and his colleagues have used the grids to watch consciousness fade under surgical anesthesia and return when the anesthesia wears off. They found each frequency gave different information on how different circuits changed with the loss of consciousness, according to Leuthardt.

"Certain networks of brain activity at very slow frequencies did not change at all regardless of how deep under anesthesia the patient was," Leuthardt says. "Certain relationships between high and low frequencies of brain activity also did not change, and we speculate that may be related to some of the memory circuits."

Their results also showed a series of changes that occurred in a specific order during loss of consciousness and then repeated in reverse order as consciousness returned. Activity in a frequency region known as the gamma band, which is thought to be a manifestation of neurons sending messages to other nearby neurons, dropped and returned as patients lost and regained consciousness.

The results appeared in December in the Proceedings of the National Academy of Sciences.

In another paper that will publish Feb. 9 in The Journal of Neuroscience, Leuthardt and his colleagues have shown that the wavelength of brain signals in a particular region can be used to determine what function that region is performing at that time. They analyzed brain activity by focusing on data from a single electrode positioned over a number of different regions involved in speech. Researchers could use higher-frequency bands of activity in this brain area to tell whether patients:

  • had heard a word or seen a word
  • were preparing to say a word they had heard or a word they had seen
  • were saying a word they had heard or a word they had seen.

"We've historically lumped the frequencies of brain activity that we used in this study into one phenomenon, but our findings show that there is true diversity and non-uniformity to these frequencies," he says. "We can obtain a much more powerful ability to decode brain activity and cognitive intention by using electrocorticography to analyze these frequencies."


Contact: Michael C. Purdy
Washington University School of Medicine

Related biology news :

1. Dynamics of chaperone protein critical in rescuing brains of Alzheimers mice from neuron damage
2. Bat brains offer clues as to how we focus on some sounds and not others
3. Trojan Horse ploy to sneak protective drug into brains of stroke patients
4. The brains of Neanderthals and modern humans developed differently
5. Cockroach brains could be rich stores of new antibiotics
6. Insect brains are rich stores of new antibiotics
7. Caltech: Gain and loss in optimistic versus pessimistic brains
8. Tiny insect brains capable of huge feats
9. Parallel brainstem circuit discovery suggests new path in Parkinsons research
10. Brains, worms and computer chips have striking similarities
11. Psychopaths brains wired to seek rewards, no matter the consequences
Post Your Comments:
Related Image:
Brain's 'radio stations' have much to tell scientists
(Date:11/12/2015)...   Growing need for low-cost, easy to ... paving the way for use of biochemical sensors ... in clinical, agricultural, environmental, food and defense applications. ... medical applications, however, their adoption is increasing in ... emphasis on improving product quality and growing need ...
(Date:11/9/2015)... , Nov. 09, 2015 ... addition of the "Global Law Enforcement ... offering. --> ) has ... Law Enforcement Biometrics Market 2015-2019" report ... and Markets ( ) has announced ...
(Date:10/29/2015)... 29, 2015   MedNet Solutions , an innovative ... of clinical research, is pleased to announce that it ... (MHTA) as one of only three finalists for a ... Small and Growing" category. The Tekne Awards honor ... superior technology innovation and leadership. iMedNet™ ...
Breaking Biology News(10 mins):
(Date:12/1/2015)... ... December 01, 2015 , ... ... relationship marketing company specializing in scientifically backed, age-defying products, is featured as ... which highlights the exponential success and unrivaled opportunities that Nerium provides. Success ...
(Date:12/1/2015)... Dallas, Texas (PRWEB) , ... December 01, 2015 ... ... its annual global meeting this month and Dr. J. Kyle Mathews ... worldwide.” This includes the new single site hysterectomy. , An experienced urogynecologist, founder ...
(Date:11/30/2015)... ... , ... Global Stem Cells Group announced that its scientific team ... isolating adipose-derived stem cells. The announcement starts a new phase toward launching the simple, ... component of the lipoaspirate obtained from liposuction of excess adipose tissue. , Lipoaspirate, ...
(Date:11/30/2015)... Dec. 1, 2015 /PRNewswire/ - BioAmber Inc. (NYSE: BIOA ), ... joined the American Business Act on Climate Pledge, alongside more ... standing with the Obama Administration to demonstrate an ongoing commitment ... outcome to the COP21 Paris climate ... Sarnia, Canada . --> BioAmber ...
Breaking Biology Technology: