Just slow down

2019-03-07 05:13:20

By Matt Walker EPILEPTIC fits are sparked by brain cells talking to each other faster than usual, according to scientists who have mathematically modelled the brain’s activity. They say that super-fast neuron communication causes a wave of activity that paralyses the brain, and suggest that epilepsy might one day be treated by drugs that slow the neurons down. The most common form of epilepsy is thought to occur when patches of neurons in a part of the brain called the temporal lobe start to fire in synchrony. It is unclear what causes this. One idea is that when certain brain cells fire they somehow persuade others to do the same. To find out more, mathematicians Raima Larter and Brent Speelman and neuroscientist Robert Worth at Purdue University in Indianapolis, Indiana, built a computer model of the interactions between neurons. They based their model on standard equations that describe how individual neurons are affected by factors such as the brain’s neurotransmitters—chemicals that can encourage neurons to fire or dampen their activity. The team then simulated the interactions of a small patch of around a thousand neurons. By changing the balance of neurotransmitters, they could make the neurons fire either chaotically or in synchrony. “We could make them behave normally or epileptically,” says Worth. The next step was to simulate a network made up of a number of these patches of neurons. It turned out that one patch could only coordinate with another if the neurons were able to communicate unusually fast—in which case they started to fire in unison, producing an epileptic wave that travelled through the simulated brain (Chaos, vol 9, p 795). Worth now wants neuroscientists to measure how fast neurons communicate in people with epilepsy. If this confirms that extra-fast communication leads to a fit, the discovery may lead to new treatments for the condition. Current drug treatments for epilepsy are often unsuccessful. Problem cells may be removed surgically, but this is a risky last resort that also often fails. A drug or electrical treatment that slowed down neuron communication might prevent seizures more safely, Worth says. Working out why brain activity suddenly synchronises in epilepsy sufferers “is the six million dollar question”, says Ley Sander, an epilepsy expert at the Institute of Neurology in London. But because the condition varies so much between individuals, he doubts whether the mathematical model will lead to a major breakthrough. “It will give us an insight into how things behave,