Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Monkeys Adapt Robot Arm as Their Own

11.05.2005


Monkeys that learn to use their brain signals to control a robotic arm are not just learning to manipulate an external device, Duke University Medical Center neurobiologists have found. Rather, their brain structures are adapting to treat the arm as if it were their own appendage.



The finding has profound implications both for understanding the extraordinary adaptability of the primate brain and for the potential clinical success of brain-operated devices to give the handicapped the ability to control their environment, said the researchers.

Led by neurobiologist Miguel Nicolelis of Duke’s Center for Neuroengineering, the researchers published their findings in the May 11, 2005, issue of the Journal of Neuroscience. Lead author on the paper was Mikhail Lebedev in Nicolelis’s laboratory. Other coauthors were Jose Carmena, Joseph O’Doherty, Miriam Zacksenhouse, Craig Henriquez and Jose Principe. The work was supported by the Defense Advanced Research Projects Agency, the James S. McDonnel Foundation, the National Institutes of Health, the National Science Foundation and the Christopher Reeve Paralysis Foundation.


In the study, Lebedev performed detailed analysis of the mass of neural data that emerged from experiments reported in 2003, in which the researchers discovered for the first time that monkeys were able to control a robot arm with only their brain signals.

In those experiments, the researchers first implanted an array of microelectrodes -- each thinner than a human hair -- into the frontal and parietal lobes of the brains of two female rhesus macaque monkeys. The faint signals from the electrode arrays were detected and analyzed by the computer system the researchers developed to recognize patterns of signals that represented particular movements by an animal’s arm.

In the initial behavioral experiments, the researchers recorded and analyzed the output signals from the monkeys’ brains as the animals were taught to use a joystick to both position a cursor over a target on a video screen and to grasp the joystick with a specified force.

After the animals’ initial training, however, the researchers made the cursor more than a simple display. They incorporated into its movement the dynamics, such as inertia and momentum, of a robot arm functioning in another room. While the animals’ performance initially declined when the robot arm was included in the feedback loop, they quickly learned to allow for these dynamics and became proficient in manipulating the robot-reflecting cursor, found the scientists.

The scientists next removed the joystick, after which the monkeys continued to move their arms in mid-air to manipulate and "grab" the cursor, thus controlling the robot arm. However, after a few days, the monkeys realized that they did not need to move their own arms. Their arm muscles went completely quiet, they kept the arm at their side, and they controlled the robot using only their brain and visual feedback.

"After these experiments, a major question remained about how the animals’ brains adapted to the transition between joystick and brain control," said Nicolelis. "Thus, drawing on the extensive data from these experiments Mikhail analyzed very carefully what happens functionally to the brain cells and the brain cell ensembles in multiple brain areas during this transition.

"And basically we were able to show clearly that a large percentage of the neurons become more ’entrained’ -- that is, their firing becomes more correlated to the operation of the robot arm than to the animal’s own arm."

According to Nicolelis, the analysis revealed that, while the animals were still able to use their own arms, some brain cells formerly used for that control shifted to control of the robotic arm.

"Mikhail’s analysis of the brain signals associated with use of the robotic and animals’ actual arms revealed that the animal was simultaneously doing one thing with its own arm and something else with the robotic arm," he said. "So, our hypothesis is that the adaptation of brain structures allows the expansion of capability to use an artificial appendage with no loss of function, because the animal can flip back and forth between using the two. Depending on the goal, the animal could use its own arm or the robotic arm, and in some cases both.

"This finding supports our theory that the brain has extraordinary abilities to adapt to incorporate artificial tools, whether directly controlled by the brain or through the appendages" said Nicolelis. "Our brain representations of the body are adaptable enough to incorporate any tools that we create to interact with the environment. This may include a robot appendage, but it may also include using a computer keyboard or a tennis racket. In any such case, the properties of this tool become incorporated into our neuronal ’space’," he said. According to Nicolelis, such a theory of brain adaptability has been controversial.

"Few researchers have been willing to go as far as postulating such extraordinary adaptability for the brain and how important this adaptability of brain circuitry is in enabling us to learn to use tools," he said. "It has long been appreciated that adaptability is a key capability of the prefrontal cortex that is a hallmark of the human brain. It gives us the ability to design, create, and use tools to do everything from lift massive weights to make microscopic manipulations.

"What Mikhail, I and our colleagues are suggesting is that a fundamental trait of higher primates, in particular apes and humans, is the ability to incorporate these tools into the very structure of the brain. In fact, we’re saying that it’s not only the brain that is adaptable; it’s the whole concept of self. And this concept of self extends to our tools. Everything from cars to clothing that we use in our lives becomes incorporated into our sense of self. So, our species is capable of ’evolving’ the perception of what we are.

"From a philosophical point of view, we’re saying that the sense of self is not limited to our capability for introspection, our sense of our body limits, and to the experiences we’ve accumulated," Nicolelis said. "It really incorporates every external device that we use to deal with the environment." The findings also have important clinical significance, said Nicolelis.

"The experiments we have conducted not only represent a proof of concept that such an external device can be directly controlled in a clinical setting," he said. "This latest analysis shows that the device is incorporated very intimately as a natural extension of the brain. This is a fundamentally important property if brain-machine interface technology is to have any clinical future. If the brain was essentially static, then paralyzed people would never be able to adapt to operate external devices with enough dexterity to make them really useful."

Importantly, said Nicolelis, truly useful "neuroprosthetic" devices will have to be dexterous enough to give patients a full range of mobility in robot arms, hands or other appendages. "Our studies show that it will not be enough to implant a few electrodes, measure a few signals and attain sufficient capability for useful devices," he said. "The ability to merely move a cursor on a screen or open or close an artificial hand is not enough to justify the use of such systems." Rather, he said, the objective in his laboratory is to develop devices that offer paralyzed people fully functional artificial appendages.

For example, he said, new experiments in his laboratory seek to enable the brain to perceive a feedback sensation from neuroprosthetic devices. Such feedback might be in the form of visual information on the effects of moving a robotic arm. Or, it might be tactile feedback fed as signals into electrodes implanted in the brain.

Such feedback would greatly enhance people’s ability to learn and use the devices, said Nicolelis. Also, such feedback would expand use of neuroprosthetics to amputees, because the devices would include all the features -- including feedback -- of real appendages.

"In our new experiments, the idea is that by using vision and touch, we’re actually going to create inside the brains of these animal a vivid perceptual image of what it is to have a third arm," he said.

Dennis Meredith | EurekAlert!
Further information:
http://www.duke.edu

More articles from Life Sciences:

nachricht Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute

nachricht Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>