The Hybrot, a small robot that moves about using the brain signals of a rat, is the first robotic device whose movements are controlled by a network of cultured neuron cells.

Steve Potter and his research team in the Laboratory for Neuroengineering at the Georgia Institute of Technology are studying the basics of learning, memory, and information processing using neural networks in vitro. Their goal is to create computing systems that perform more like the human brain.

Potter, a professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, presented his most recent findings last month during the Third International Conference on Substrate-Integrated Microelectrodes in Texas.

As the lead researcher on a $1.2 million grant from the National Institutes of Health, Potter is connecting laboratory cultures containing living neurons to computers in order to create a simulated animal, which he describes as a "neurally-controlled animat."

"We call it the 'Hybrot' because it is a hybrid of living and robotic components," he said. "We hope to learn how living neural networks may be applied to the artificial computing systems of tomorrow. We also hope that our findings may help cases in which learning, memory, and information processing go awry in humans."

The team uses networks of cultured rodent brain cells as the Hybrot's brain, and has essentially given the cultured neural networks a body in the form of a mobile robot. Potter's group hopes the research will lead to advanced computer systems that could some day assist in situations where humans have lost motor control, memory or information processing abilities. The neural interfacing techniques they are developing could be used with prosthetic limbs directly controlled by the brain. Advances in neural control and information processing theory could have application, for example, in cars that drive themselves or new types of computing architectures.

Inside Potter's lab, a droplet containing a few thousand living neurons from rat cortex is placed on a special glass petri dish instrumented with an array of 60 micro-electrodes. The neurons are kept alive in an incubator for up to two years using a new sealed-dish culture system that Potter developed and patented. The neural activity recorded by the electrodes is transmitted to the robot, the Khepera, made by K-Team S.A, which serves as the body of the cultured networks. It moves under the command of neural activity that is being transmitted to it, and information from the robot's sensors is sent back to the cultured net in the form of electrical stimuli.

Quoted:
Very very interesting, this is the first step towards a neural interface with computers. It will be interesting to follow the developments of this research, integrating electronics with the human brain will be very useful. Got crappy eyes? Get bionic ones!

May 15, 2003
Wired to the Brain of a Rat, a Robot Takes On the World
By ANNE EISENBERG


HE nerve center of a conventional robot is a microprocessor of silicon and metal. But for a robot under development at Georgia Tech, commands are relayed by 2,000 or so cells from a rat's brain.

A group led by a university researcher has created a part mechanical, part biological robot that operates on the basis of the neural activity of rat brain cells grown in a dish. The neural signals are analyzed by a computer that looks for patterns emitted by the brain cells and then translates those patterns into robotic movement. If the neurons fire a certain way, for example, the robot's right wheel rotates once.

The leader of the group, Steve M. Potter, a professor in the Laboratory for Neuroengineering at Georgia Tech, calls his creation a Hybrot, short for hybrid robot.

"It's very much a symbiosis," he said, "a digital computer and a living neural network working together."

Dr. Potter has been building the system of hardware, software, incubators and rat neurons that constitute the Hybrot since 1993, when he was a postdoctoral student at the California Institute of Technology. He and his group have not only introduced the neurons to the world outside their dish; the team has also closely monitored minute changes that take place in the shape and connections of the neurons as they are stimulated, using techniques like time-lapse photography and laser imaging.

Dr. Potter hopes that close observation of how brain cells behave as they are exposed to a world of sensation will help researchers understand the way small groups of neurons go about learning. "If the network begins to get better at a job," he said, "we will watch what changed within the network to allow it to do that."

Dr. Jonathan Wolpaw, laboratory chief and professor of neuroscience at the Wadsworth Center of the New York State Department of Health and the State University of New York at Albany, said that Dr. Potter's research could yield a simple system for exploring the capacity of neurons and circuits to change based on incoming activity.

"These changes could be analogues of what happens in learning," Dr. Wolpaw said. "You are dealing with neurons, the same tissue as in a brain," although in a different setting and with different circuitry. "Some things presumably are in common, for example, the neuron's capacity for plasticity," he said.

In Dr. Potter's hybrid system, the layer of rat neurons is grown over an array of electrodes that pick up the neurons' electrical activity. A computer analyzes the activity of the several thousand brain cells in real time to detect spikes produced by neurons firing near an electrode.

A silver three-wheeled model of the robot is commercially available through the Swiss robotics maker K-Team (www.k-team.com) for about $3,000 and is about the size of a hockey puck. It trundles along at a top speed of one meter per second.

"We assign a direction of movement, say, a step forward, that is automatically triggered by a pattern of spikes," said Thomas DeMarse, a former member of Dr. Potter's group who is an assistant professor in the department of biomedical engineering at the University of Florida. "Twenty of these patterns, for instance, means 20 rotations of the wheel."

As the robot moves, it functions as a sensory system, delivering feedback to the neurons through the electrodes. For example, Mr. DeMarse said, the robot has sensors for light and feeds electrical signals proportional to the light back to the electrodes. "We return information to the dish on the intensity of light as the robot gets closer and the light gets brighter."

The researchers monitor the activity of the neurons for new signals and new connections. Dr. Potter said that the feedback mechanism was crucial to the functioning of the neural network. In traditional, isolated cultured networks, he said, in which neurons are not connected to a body, the activity patterns of the neurons are largely pathological. "They behave in an aberrant way," he said. "It's a symptom of sensory deprivation, because the neurons are not receiving the input they usually get."

He decided to provide a body for the neurons early in his research, first in computer simulation and then in reality, so that neurons would have feedback. In that way, if the cells learned, he and his group might observe the changes that came about in the network. "People say learning is a change in behavior that comes from experience," he said. "For a cultured network to learn, it must first be able to behave."

There is an analogy to the human nervous system in the feedback loop developed by Dr. Potter, said Nicholas Hatsopoulos, an assistant professor in the department of organismal biology and anatomy at the University of Chicago.

Dr. Hatsopoulos also works on brain-machine interfaces, including ways that brain signals may one day be used to move prosthetic devices.

"Potter's device has sensors that pick up information, and then the signals go back to the dish and stimulate the cells," he said. Similarly, he said, "signals out of the brain control the arm, but there are also sensors in the muscles and skin that send information back, too."

Such feedback loops are necessary to basic research in brain-machine interactions, he said. Researchers need not only to record signals that drive a device but also take signals from sensors and stimulate the nervous system. "Closing the loop will be a key issue in moving this field to the next level, for the feedback presumably helps learning," he said.

Miguel A. L. Nicolelis, a neuroscientist at Duke University, has identified signals generated by a monkey's brain as it gets ready to move, and then used the signals to move a robotic arm. "We are discovering that when animals learn to operate a robotic device, the operation changes the sensory and motor maps of the animal," he said. "Steve is looking for the same thing at the cellular level."

Dr. Potter has not yet demonstrated learning in his network but said he might be able to do so within six months. In experiments, Dr. Potter said he hoped to observe the Hybrot following an object at a certain distance.

"The next step is to watch it to see if it becomes better at following this object," he said. "That would become exciting."