Video | Business Headlines | Internet | Science | Scientific Ethics | Technology | Search

 

Where’s That Coming From? Research Makes It Easier To Pinpoint Brain Activity In EEG Studies

Skoltech researchers have proposed a fast and accurate numerical method of addressing the problem plaguing electroencephalography (EEG) studies that monitor the brain’s electrical activity — having to laboriously locate the source of EEG signal in the brain due to the low spatial resolution of this method. The new approach may help improve both medical and research applications of EEG. The paper was published in IEEE Transactions on Biomedical Engineering.

Suppose you want to study the properties and activity of a human brain without cracking open the brain owner’s skull (invasive research methods have their applications too, but those are understandably limited). You could put the brain, with its owner, into an MRI machine, and that’s how most of those trendy studies in the news are done. MRI can offer great spatial resolution in that you could locate brain activations quite accurately. But it is exasperatingly slow, capturing processes that take minutes when a human brain’s typical reaction times are in the span of tens and hundreds of milliseconds. Then there’s MEG, magnetoencephalography, which is very accurate and more attuned to the quick thinking of humans but requires extremely expensive equipment that needs to be cooled down with liquid helium and operated in a magnetically shielded room.

EEG, electroencephalography, however, is much simpler and easier to set up and use, and it provides a very good temporal resolution; that is why it is so widely used in healthcare and research. There’s just one catch, explains Mikhail Malovichko, a coauthor of the study: even a small active area of the cortex generates electrical potential on a large portion of the surface of the head, so an accurate localization of small active patches of the brain is a challenging mathematical task, the so-called inverse EEG problem.

To solve this problem, researchers normally use MRI scans to build a model of the subject’s head, place some candidate electric dipoles, essentially best guesses for where the signals might be coming from, and have a computer tinker with the model until its output fits the actual signal measured on the head. For this, the machine has to first solve many complementary forward problems: figure out what kinds of electrical activity these candidate dipoles would generate.

“This approach is universal. The preliminary solution of forward problems reduces the inverse EEG problem to a small system of linear equations, which is of the same type regardless of the position of candidate dipoles and the numerical method used to solve the forward problem. But if one needs to consider each subject's anatomical features, then the forward problem has to be solved by the finite element method, a very resource-intensive numerical procedure,” says Nikolay Koshev, another coauthor of the study.

That takes quite a lot of time, so Malovichko and his colleagues from the Skoltech Center for Data-Intensive Science and Engineering (CDISE) have proposed to approach this challenge in a different way. Their solution for the inverse EEG problem directly “backpropagates” measured signals from the skin inside the head down to the cortex. This requires reframing the whole task as a Cauchy problem, a type of mathematical problem that is known to be unstable for EEG: that means even slight deviations in the input, for instance, from unavoidable measurement errors, can significantly skew the result. Yet recent research has brought new approaches to tackling these unstable problems efficiently, and the scientists used them in their research.

“In essence, instead of treating each candidate electric dipole separately and having to solve the forward problem first for each of them, the algorithm now has to solve just one inverse problem, which is, however, of a rather peculiar kind. This helps speed up the processing of EEG data and increases accuracy for source localization; in addition, the algorithm explicitly incorporates the information on how the brain surface is shaped,” Mikhail Malovichko says.

“We believe our approach will open the door for a new generation of fast and accurate algorithms for the inverse EEG problem,” he concludes.

© Scoop Media

 
 
 
Business Headlines | Sci-Tech Headlines

 

RNZ: Porirua Most Expensive Region To Rent, According To Trade Me

A rental website shows this town is now New Zealand's most expensive region to rent a house, ahead of Wellington and Auckland cities. More>>

ALSO:


Stats NZ: Nearly 1,000 More Big Businesses Now Than Two Decades Ago – Media Release

There are now 2,690 big businesses in New Zealand employing more than 100 staff – nearly 1,000 or 58 percent more than 20 years ago, Stats NZ said today. Over the 20 years to February 2020, the total number of enterprises in New Zealand increased ... More>>

ALSO:

RNZ: Housing Boom Could Get Worse, Economist Warns

Economists are calling on the Reserve Bank to reinstate lending restrictions, warning the housing market is spiralling out of control. More>>

ALSO:

Westpac: Sets Out Plan To Go Cheque-Free

Westpac NZ has announced details of its plan to phase out cheques, after signalling in May that it would be supporting a move to other forms of payment. Cheques will cease to be available as a means of payment after 25 June 2021. Westpac NZ General ... More>>

ALSO:

NZTA: Major New Zealand Upgrade Programme Projects Go To Tender

Two major New Zealand Upgrade Programme projects are beginning tenders for construction. The New Zealand Upgrade Programme is a $6.8 billion investment to get our cities moving, to save lives and boost productivity in growth areas. The first Auckland ... More>>

Reserve Bank: RBNZ Seeks To Preserve Benefits Of Cash

The Reserve Bank – Te Pūtea Matua is taking on a new role of steward of the cash system “to preserve the benefits of cash for all who need them”, Assistant Governor Christian Hawkesby told the Royal Numismatics Society of New Zealand annual conference ... More>>

ALSO:


CERT NZ: Malicious Computer Virus Targeting New Zealanders

CERT NZ, the government agency which supports organisations and individuals affected by cyber security incidents, says a recent surge of increasingly sophisticated malware attacks is affecting everyday New Zealanders as well as large organisations. The ... More>>

ALSO:

Economy: NZ Small Business Recovery Continues In September

Xero, the global small business platform, today released its Small Business Insights (XSBI) for September revealing an uptick in small business jobs and year-on-year revenue growth in New Zealand. Nationwide, the average number of jobs in the small ... More>>

ALSO:


Courts: Businessman Eric Watson Sentenced To A Four-Month Jail Term

New Zealand businessman Eric Watson has been sentenced to a four-month jail term in the UK for contempt of court, TVNZ reports. More>>

OECD: Area Employment Rate Falls By 4.0 Percentage Points, To 64.6% In Second Quarter Of 2020

The OECD area employment rate – the share of the working-age population with jobs – fell by 4.0 percentage points, to 64.6%, in the second quarter of 2020, its lowest level since the fourth quarter of 2010. Across the OECD area, 560 million persons ... More>>

Spark: Turns On 5G In Auckland And Offers A Glimpse Into The Future Of Smart Cities

Spark turned on 5G in downtown Auckland today and has partnered with Auckland Transport (AT) to showcase some of the latest in IoT (Internet of Things) technology and demonstrate what the future could look like for Auckland’s CBD with the power of 5G. 5G is ... More>>

Stats NZ: Monthly Migration Remains Low

Since the border closed in late-March 2020, net migration has averaged about 300 a month, Stats NZ said today. In the five months from April to August 2020, overall net migration was provisionally estimated at 1,700. This was made up of a net gain ... More>>