Navigation Links
CWRU researchers find epileptic activity spreads in new way

Researchers in the biomedical engineering department at Case Western Reserve University have found that epileptic activity can spread through a part of the brain in a new way, suggesting a possible novel target for seizure-blocking medicines.

Evidence from a series of experiments and computer modeling strongly suggests individual cells in a part of the brain, known as the hippocampus, use a small electrical field to stimulate and synchronize neighboring cells, spreading the activity layer by layer.

The scientists report the discovery in the Journal of Neuroscience this week.

"We know there are several ways for neurons to talk with one another: chemical and electrical synaptic transmission and diffusion of ions," said Dominique Durand, professor of biomedical engineering at Case Western Reserve and the study's senior author. "But this shows a new mechanism. Neurons talk to each other cell to cell using electrical fields, propagating a wave of activity."

Durand worked with graduate students from Case Western Reserve's Neural Engineering Center: Mingming Zhang, Chen Qiu, Rajat J. Shrivacharan and Thomas P. Ladas; and Senior Research Associate Luis E. Gonzales-Reyes to investigate how epileptic seizure activity starts and spreads in the brain.

They inserted a 64-channel microelectrode array in the unfolded hippocampus of a mouse model to monitor its activity. They then injected the hippocampus, which is known to be involved in the most common form of epilepsy, with a drug to make the hippocampus epileptic.

They blocked chemical synapses from transmitting signals between neurons by reducing the calcium ion concentration below the level typically involved in signaling. They then blocked what are called "gap junctions," which electrically transmit signals across synapses, by injecting the antimalarial drug mefloquine, known to hamper the process.

Their tests showed that epileptic activity continued to spread at a speed of about 0.1 meter per second with or without synaptic transmission.

The propagation speed eliminated the third known route of epileptic propagationsignaling by diffusion of sodium and potassium ions across brain cell membranes. Diffusion is too slow to be the method of transmission.

The researchers were left with the fourth known way that neurons communicate: electrical fields. When a group of cells fire together, they can generate currents and electric fields that can be large enough to excite their neighbors.

Computer simulations with a large set of neurons confirmed that a weak electrical field could, by itself, spread epileptic signals at the speed that matched their experimental results. The computer model also predicted that signal transmission would change speeds depending on the distance between neurons.

The researchers verified the prediction by injecting drugs that would either expand or decrease the space between cells. The closer the cells, the faster the transmission. The more distant the cells, the slower the transmission untilat a certain distancethe signal failed to propagate.

For some time, doctors have used diuretics to treat some types of epilepsy.Diuretics are known remove water from cells and but their anticonvulsant properties are not known, Durand said.

As water is removed from cells and enters the extracellular space, it increases the space between cells and may be pushing them beyond the reach of the weak electrical field, he said.

The researchers say that this finding does not diminish the importance of synaptic transmission in epilepsy but points to another synchronizing and propagation mechanism.

But "this discovery has implications for epilepsy," Durand said. "If cells in an excited state can talk to or influence each other, they can synchronize to a seizure-like state, propagate to neighbors thereby generating a full-blown seizure."

The electrical fields and the process of synchronization and propagation may be new targets for medicines or other treatments to prevent or limit seizures.

The researchers are now investigating a way to directly test the effect of electric field on seizure generation and propagation.

Contact: Kevin Mayhood
Case Western Reserve University

Related medicine news :

1. IU School of Medicine researchers awarded $300,000 GE/NFL grant to study concussions
2. UGA researchers discover origin of unusual glands in the body
3. Air Force awards over $1 million to UC trauma researchers
4. UCLA researchers develop risk calculator to predict survival in heart failure patients
5. Mount Sinai researchers find promising new drug targets for cocaine addiction
6. Researchers identify possible explanation for link between exercise & improved prostate cancer outcomes
7. Researchers awarded grant from the DeGregorio Family Foundation
8. Penn researchers run successful HIV intervention project in S. Africa
9. Not just clean but spotless -- Researchers show how cells tidy up
10. Loyola researchers identify risk factor for life-threatening disease in preemies
11. UNC researchers harness suns energy during day for use at night
Post Your Comments:
(Date:6/25/2016)... ... ... closing of Bruton Memorial Library on June 21 due to a possible lice infestation, as ... of head lice: the parasite’s ability to live away from a human host, and to ... one in the event that lice have simply gotten out of control. , As lice ...
(Date:6/25/2016)... ... June 25, 2016 , ... As a lifelong Southern Californian, ... and his M.D from the David Geffen School of Medicine at UCLA. He trained ... Angeles to complete his fellowship in hematology/oncology at the UCLA-Olive View-Cedars Sinai program where ...
(Date:6/25/2016)... ... 2016 , ... Conventional wisdom preaches the benefits of moderation, whether it’s a ... the bar too high can result in disappointment, perhaps even self-loathing. However, those who ... , Research from reveals that behind the tendency to set ...
(Date:6/24/2016)... (PRWEB) , ... June 24, 2016 , ... June 19, ... the dangers associated with chronic pain and the benefits of holistic treatments, Serenity ... who are suffering with Sickle Cell Disease. , Sickle Cell Disease (SCD) is a ...
(Date:6/24/2016)... ... ... Global law firm Greenberg Traurig, P.A. announced that 20 Florida attorneys are ... for this recognition are considered among the top 2 percent of lawyers practicing within ... of this year’s Legal Elite Hall of Fame: Miami Shareholders Mark D. Bloom, ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... , June 24, 2016 Research and ... Market for Companion Diagnostic Tests" report to their offering. ... for Companion Diagnostics The World Market for ... personalized medicine diagnostics. Market analysis in the report includes the ... Market (In Vitro Diagnostic Kits) by Region (N. America, EU, ...
(Date:6/24/2016)... Tenn. , June 24, 2016  Arkis ... providing less invasive and more durable cerebrospinal fluid ... in funding.  The Series-A funding is led by ... Lighthouse Fund, and other private investors.  Arkis, new ... neurosurgical instrumentation and the market release of its ...
(Date:6/23/2016)... DUBLIN , June 23, 2016 ... the "Pharmaceutical Excipients Market by Type (Organic Chemical ... Preservative), Formulation (Oral, Topical, Coating, Parenteral) - Global Forecast ... The global pharmaceutical excipients ... 2021 at a CAGR of 6.1% in the forecast ...
Breaking Medicine Technology: