UCI researchers to develop non-invasive, cheaper and more accurate method for mapping brain regions related to epileptic seizures, autism
UCI researchers to develop non-invasive, cheaper and more accurate method for mapping brain regions related to epileptic seizures, autism
- November 16, 2015
- Project utilizes new MEG technology based on Sagnac interferometer developed by UCI physicist
Pre-surgical teams may soon have a more reliable, cost effective and non-invasive
way to help pinpoint areas in a patient’s brain causing epileptic seizures. A new
method for magnetoencephalography (MEG), developed by UCI professors, will allow researchers
to measure brain activity at a millimeter scale with millisecond temporal resolution.
The technique also has applications in non-invasive mapping of brain function and
brain connectivity in disorders such as autism.
“Measuring the magnetic field of the brain using MEG is potentially the best approach
for accurately mapping brain activity because it has very high temporal resolution
and can be used to localize brain activity through magnetic source imaging,” says
Ramesh Srinivasan, UCI cognitive sciences and biomedical engineering professor. However,
current MEG technology has been developed using expensive coils that have to be kept
at absolute zero temperature; as a consequence, there’s a more than 3 centimeter thick
layer of insulation between the scalp and sensor. The impact of this distance, says
Srinivasan, is weaker signals from the brain and reduced spatial resolution. The equipment
costs are also in the millions and the liquid helium cooling systems are expensive
to maintain.
Working together with Jing Xia, astronomy and physics associate professor, Srinivasan
is developing a method to measure MEG using sensors at room temperature that are placed
directly against the scalp. They will adapt Sagnac interferometer technology developed
by Xia for magnetic field measurements in physics application. The Sagnac interferometer
uses laser-charged pure atomic vapor as a sensing media that will measure the brain’s
magnetic field.
“The Sagnac interferometer allows you to calibrate and measure the size of the magnetic
field coming from the brain.” says Xia.
The laser aligns all of the atomic spins; if there’s no magnetic field, they’ll spin
in one particular direction. If a magnetic field is imposed on it, the spins of the
atoms are modified which can be detected by the interaction of the atomic media with
a probe laser.
“We estimate that the cost of the Sagnac MEG will be one-tenth the cost of a conventional
MEG machine, with 5 times higher spatial resolution and 10 times higher sensitivity,
potentially allowing for recording from deep brain structures,” Srinivasan says.
The technology has immediate implications in pre-surgical mapping by clinicians and
numerous possibilities in basic and clinical research on disorders including autism
and epilepsy.
“In epilepsy research, the new equipment and procedure would provide useful information
on where seizures are occurring without a doctor opening a patient’s skull, potentially
reducing the need for extensive intracranial mapping,” says Srinivasan.
He and Xia are affiliated with UCI’s Center for Autism Research and Translation which
provided seed funding for this research. One of their long-term goals is to apply
MEG for non-invasive brain mapping of connectivity in autistic patients.
“One of the most reliable markers of autism is changes in connectivity measured using
EEG. Professor Xia and I would like to perform this research with our new MEG technology
to improve the specificity of brain areas showing changes in connectivity,” says Srinivasan.
The scientists have received $367,000 from the National Institutes of Health to modify
the interferometer to work for MEG. When complete, they’ll begin testing with phantom
heads and then on human subjects. Funded work began in July and will run through June
2017.
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