At first the brain does not know what to do.
"If you take these cells out of the cortex and you put them into one of these dishes, you remove all of the inputssensory systems like vision or hearingthat they would normally have," DeMarse said. "The only thing that's going on is the spontaneous activity of reconnecting."
But as the neurons begin to receive information from the computer about flight conditionssimilar to how neurons receive and interpret signals from each other to control our bodiesthe brain gradually learns to fly the aircraft.
"The neurons will analyze data from the computer, like whether the plane is flying level or is tilted to one side," DeMarse said. "The neurons respond by sending signals to the plane's controls to alter the flight path. New information is sent back to the neurons, creating a feedback system."
Neural network research may be setting the stage for the creation of so-called hybrid computers based on biological systems.
Silicon-based computers are very accurate and fast at processing some kinds of information, but they have none of the flexibility of the human brain.
"Despite the power of current digital technology, the adaptability of the neuron and its hybrid digital, analog, and chemical information representation may allow novel computing devices to be created," said George Wittenberg, an assistant professor of neurology at Wake Forest University in Winston-Salem, North Carolina.
Brains can easily make certain kinds of computations that computers are unable to do, such as answering open-ended questions about what happened sometime in the past.
"To do a search like that in silicon is pretty difficult, unless you program [a computer] to specifically answer that question," DeMarse said. "Yet these neurons are able to do this in rats and in humans all the time."
Understanding how neurons distribute information and encode it would allow scientists to take those rules and develop a silicon system that operates similar to the neurons, yet has the retention capacity of a silicon computer.
Such living computers may someday be used to fly unmanned airplanes or handle tasks that are dangerous for humans, such as search-and-rescue missions or bomb-damage assessments.
Neural-network research may also help scientists better understand what causes neural disorders. DeMarse's studies, for example, are investigating the evolution of epilepsy.
"We have bundles of electrodes that we insert into the rat brain," he said. "We can do treatment in the animals that [causes] epileptic seizures. It allows us to look at the neural activity over time to see what exactly is changing in terms of that activity leading up to the seizures."
While scientists know a lot about the neurons themselves, DeMarse says little is known about how neurons encode information, for example.
"We're really working at the basic level," he said, "trying to figure out what sort of computation is going on and how it might be occurring."
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