Brain Probes Give Rats Their Marching Orders

Transmitting wireless signals directly into the brain, a group of scientists has produced the ultimate lab rat--an animal that can be guided by remote control over fences, up trees, through pipe and across rubble at distances up to a third of a mile.

The researchers, from the State University of New York and Drexel University, say their work with brain implants ultimately could produce “robotic” rats that could be used for rescue missions, video surveillance or detecting explosives.

The researchers implanted electrical probes in critical centers of the brain that affect what an animal senses and how it behaves. They then trained the animals to respond to impulses sent through the implants. Once trained, the animals could be readily controlled by an operator with a laptop computer transmitting to a small backpack receiver worn by each rat.

“We developed a way to create seemingly complex behaviors in animals by generating cues and rewards,” said lead researcher Sanjiv Talwar at the SUNY Downstate Medical Center in Brooklyn. “The rats could almost understand what you wanted them to do.”

The work, published today in the journal Nature, is pretty amazing, say researchers who work in the field of mind-machine interactions. But, scientists acknowledge, many people may find such remote brain control disturbing.

The drive behind the research is a humanitarian one--finding better ways to build artificial limbs and other prosthetics that could communicate fully with nerves. Nonetheless, “You would want to be careful how far you took this kind of research,” said Caltech neural expert Richard Andersen. “The implications are a little scary.”

The brain stimulation technique used to condition the laboratory rats could almost certainly work in other species, including humans, said Paul W. Glimcher, an expert at New York University on the neurobiology of decision-making.

“That is what is so disturbing about it,” Glimcher said. “It is clearly a technique that if applied to humans would have huge legal, moral and ethical ramifications. That raises real questions about whether a technology of this type could be used to undermine the autonomy of an individual decision-maker.”

Previously, scientists had only been listening to the electrical signals generated by brain cells. They are able to decipher the brain’s output and use it to activate machines.

Several laboratories have used brain cell activity from rats and monkeys to control robotic arms, even when the device--connected through the Internet--is hundreds of miles away. Only last month researchers at Brown University successfully wired a monkey to a computer so its mental activity could move a cursor.

With this latest accomplishment, scientists are talking back directly to brain cells.

To perform the experiment, the scientists injected signals directly into sensory and learning areas of the brain. They want to learn how to create the feedback of touch and other sensations normally provided by a living limb.

“We are bringing information back into the brain,” said John Chapin, a professor of physiology and pharmacology at the Downstate Medical Center, who was a senior researcher on the project.

In all, the scientists successfully wired five rats in a project funded by the Department of Defense.

Each animal had three sets of hair-thin wires implanted in its brain. One wire went to a part of the forebrain that generates a sensation as a reward to reinforce behavior. The other electrodes went to regions responsible for the rat’s whiskers, which it uses to navigate.

The electrodes, in turn, were connected to a wireless transmitter in a lightweight backpack powered by a 9-volt battery. The rat’s backpack also contained a tiny video camera. The researchers are considering adding other sensors, such as a global positioning system unit to better track the rat as it moves.

The scientists steered the rats by activating the whisker centers, creating the sensation of a touch on one side or the other. Sending signals to the brain’s reward center reinforced correct behavior.

“In some real sense, they have produced a computer bridle,” said Glimcher. “Instead of a whip and carrot, they use direct activation of the learning circuit in the brain itself, which is pretty cool.”

The rodents could even be commanded to overcome their natural caution and venture into brightly lit, open areas--environments they normally would avoid.

“These guys are showing that there is a way to deliver the signal to the brain directly and apparently the signal can be interpreted. This is a very important result,” said Miguel Nicolelis at Duke University, who also works on brain-machine interfaces.

It may be most important as a harbinger of things to come, as brain researchers become more adept at manipulating the organ responsible for thought and behavior, several experts said.

“Long before we get to the real ethical problems posed by changing our genes, we will have to deal with the consequences of the revolution in neuroscience,” said Arthur Caplan, director of the University of Pennsylvania Bioethics Center.

“This rat research is primitive stuff, but it is a shot across our bow that should alert us to the potential consequences.”