Suppressing epileptic seizures via Anderson localization

March 22, 2017, Carnegie Mellon University Electrical and Computer Engineering
This wearable device would noninvasively stop the progression of seizure activity in the brain by launching a random spatio-temporal pattern of ultrasonic waves from outside of the brain to target populations of neurons in various locations across the cortex to stop the seizure propagation in its tracks. Credit: Carnegie Mellon University Department of Electrical and Computer Engineering

More than 50 million people of all ages suffer from epilepsy, otherwise known as seizure disorder, the fourth most common neurological disease in the world. Patients diagnosed with epilepsy often experience recurrent seizures triggered by the firing of a large collection of neurons in the brain. This ultimately generates a high-energy wave that spreads across the surface of the brain, resulting in numerous physical effects such as erratic body shaking, unconsciousness, exhaustion, and pain.

Many epileptic patients try to suppress their seizures by taking antiepileptic medications or by following a special diet, but other patients opt to endure invasive surgeries to remove seizing portions of their cortex or to implant neurostimulators in their body.

Unlike these invasive procedures, Carnegie Mellon University's Maysam Chamanzar, professor of electrical and computer engineering, together with UC Berkeley's Reza Alam, professor of mechanical engineering, introduce a non-invasive approach to mitigate seizures in a paper recently published in the Journal of The Royal Society Interface. Chamanzar and his colleagues, Ben Zhang, a current mechanical engineering student at UC Berkeley, and Reza Alam, based their approach on a wave phenomenon called Anderson localization, a phenomenon discovered by P.W. Anderson (Nobel Laureate, 1977) that explains how random disruptions of the medium can decrease the vitality of waves. To understand the concept of localization, Chamanzar prompts readers to consider how ocean waves lose their energy as they spread over irregular topography (random medium). Although Anderson discovered localization in the context of solid-state physics, Chamanzar and his colleagues prove that localization can also be applied in the context of epileptic seizures. According to their research paper:

Epileptic seizures are due to collective pathological activity of a large population of neurons. Therefore, from a mesoscale perspective, a seizure can be considered as a synchronized collective of waves propagating across cortical regions. We show here that this wave propagation behavior can be disrupted through local modulation of neurons (hypothetically using a phased-array of ultrasound transducers) to create multiple local modes that can dissipate the seizure wave energy.

This short video shows a mesoscopic map of the cortical activity. At the beginning, we have the normal brain activity. Then Seizure starts (as the title shows). And after the Anderson localization starts (called excitation in the title) the seizure is suppressed and brain returns to the normal state of activity. Credit: Carnegie Mellon University Department of Electrical and Computer Engineering

In their study, Chamanzar and his co-authors used the mesoscale cortical model to simulate tonic-clonic seizure activity. Then, they disrupted the seizure activity by applying the Anderson localization phenomenon to modulate different parameters governing the firing rates of neurons. Overall, Chamanzar and his colleagues discovered that the localization of seizure waves is most effective when randomization is applied to the parameters describing the mean excitatory threshold potential, which suppresses seizures by decreasing the seizure amplitude, and the inhibitory population threshold potential, which suppresses seizures by decreasing the frequency of seizure oscillations. By properly randomizing these two variables together, Chamanzar shows that epileptic seizures can be localized and ultimately suppressed. Chamanzar says that this suppression method is significant because it can immediately attenuate epileptic seizures.

"Mitigating seizures right at the starting moment is crucial. Using our technique, we do not need to have a-priori knowledge of where exactly the seizure originates. As soon as the onset of a seizure is detected, our method can suppress the seizure waves effectively."

Chamanzar and his colleagues envision that doctors could test this mitigation method by having epileptic patients wear a device that would noninvasively stop the progression of in the brain. This device would detect the onset of seizures and launch a random spatio-temporal pattern of ultrasonic waves from outside of the brain to target populations of neurons in various locations across the cortex to stop the propagation in its tracks. Such a non-invasive device can be designed in the form of a wearable hat that automatically suppresses epilepsy seizures right after the onset of seizures from the start. This is a first step towards devising a new modality for mitigating epilepsy. Chamanzar and his collaborators believe that it is conceivable for the brain to be trained to self-mitigate and suppress right at the onset, if this modality is tried for enough number of times.

"Our proposed method is the first step towards non-invasive suppression of seizures using a novel modality," said Chamanzar. "When it comes to modulating the brain activity to mitigate a disorder, we need to think about new paradigms for interfacing that do not suffer from the limitations of conventional invasive methods."

The Journal of The Royal Society Interface publishes high-quality articles online and in bimonthly print editions that focus on a subject at the interface of the physical and life sciences. These articles must "aim to facilitate cross-disciplinary research across this traditional divide by acting as a forum accessible to all."

Explore further: New mech­an­ism un­der­ly­ing epi­lepsy found

More information: Benjamin J. Zhang et al. Suppression of epileptic seizures via Anderson localization, Journal of The Royal Society Interface (2017). DOI: 10.1098/rsif.2016.0872

Related Stories

New mech­an­ism un­der­ly­ing epi­lepsy found

February 27, 2017
Prolonged epileptic seizures may cause serious problems that will continue for the rest of a patient's life. As a result of a seizure, neural connections of the brain may be rewired in an incorrect way. This may result in ...

Surprising results from study of non-epileptic seizures

December 2, 2012
A Loyola University Medical Center neurologist is reporting surprising results of a study of patients who experience both epileptic and non-epileptic seizures.

Using network science to help pinpoint source of seizures

December 17, 2015
The ability to reliably pinpoint the anatomical source of epileptic seizures, different for each patient, remains elusive. One third of patients do not respond to medication and an alternative can be surgery to locate and ...

Robot reduces need for open brain surgery to map epileptic seizures

January 23, 2017
A minimally invasive robotic device is eliminating the need for some patients to undergo open brain surgery to pinpoint the origin of their epileptic seizures. The device, in use at Duke and a small handful of epilepsy centers ...

Heart rate variability predicts epileptic seizure

April 1, 2016
Epilepsy is a neurological disorder that causes seizures of many different types. Recent research from Japan has found that epileptic seizures can be more easily predicted by using an electrocardiogram to measure fluctuations ...

Patient should talk to doctor about interest in discontinuing anti-epileptic medication

April 8, 2016
Dear Mayo Clinic: I was diagnosed with epilepsy three years ago at the age of 29. I've been on medication since then and haven't had another seizure. Is it true that, for some people, epilepsy is not necessarily a lifelong ...

Recommended for you

New technique helps uncover changes in ALS neurons

June 22, 2018
Northwestern Medicine scientists have discovered that some neurons affected by amyotrophic lateral sclerosis (ALS) display hypo-excitability, using a new method to measure electrical activity in cells, according to a study ...

Broken shuttle may interfere with learning in major brain disorders

June 22, 2018
Unable to carry signals based on sights and sounds to the genes that record memories, a broken shuttle protein may hinder learning in patients with intellectual disability, schizophrenia, and autism.

Watching stem cells repair spinal cord in real time

June 22, 2018
Monash University researchers have restored movement and regenerated nerves using stem cells in zebra fish where the spinal cord is severely damaged.

Scientists discover fundamental rule of brain plasticity

June 21, 2018
Our brains are famously flexible, or "plastic," because neurons can do new things by forging new or stronger connections with other neurons. But if some connections strengthen, neuroscientists have reasoned, neurons must ...

Waking up is hard to do: Prefrontal cortex implicated in consciousness

June 21, 2018
Philosophers have pondered the nature of consciousness for thousands of years. In the 21st century, the debate over how the brain gives rise to our everyday experience continues to puzzle scientists. To help, researchers ...

Researchers find mechanism behind choosing alcohol over healthy rewards

June 21, 2018
A new study links molecular changes in the brain to behaviours that are central in addiction, such as choosing a drug over alternative rewards. The researchers have developed a method in which rats learn to get an alcohol ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

2 / 5 (4) Mar 22, 2017
The end of the story is the payoff, the programming of the brain to do it itself.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.