Researchers find new learning strategy

In so doing, Kurt Thoroughman, Ph.D., assistant professor of biomedical engineering at Washington University, and his graduate student, Michael Fine, have discovered a new learning strategy they call categorical adaptation in which steps of learning are sensitive to the direction of error, but do not scale proportionally with the size of the error. Eventually, their findings could have an impact in the rehabilitation of people with neurological ailments such as strokes by making use of different learning environments.

If you make a movement error in one direction, in makes sense that your next movement would correct toward the opposite direction, in exact proportion to the error. An example would be a pitcher correcting to the right, after missing home plate to the left with a pitch.

"We show that learning does not necessarily scale with error," said Thoroughman. "I think we have uncovered a part of human adaptation that certainly doesn't do that. We are not claiming that all previous theories are false in the behaviors that were captured. It's just that we have for the first time found a part of human adaptation that clearly does not scale with the size of the error."

Thoroughman is interested in how humans learn motor skills incrementally, how information from a single movement can inform the generation of the next movement. He and Fine asked volunteers to make reaching movements while holding the end of a robotic arm. Volunteers were trained for about 40 minutes a day for two days. On each day, subjects were asked to make half-second, 10-centimeter reaching movements, directed away from their bodies.

Subjects learned the baseline task on the first day. On the second day Thoroughman and Fine tricked volunteers by having the robotic arm push the human hand with a perturbing pulse of force in 20 percent of movements. The pulse pushed subjects from their normal trajectory, either to the right or the left, with three different pulse strengths. Thoroughman and Fine observed how the pulse altered that trajectory and how subjects corrected, or adapted, in the very next movement.

"The pulse should induce an error in that movement that scales with the size of the pulse," said Thoroughman, who also has appointments in Neurobiology and Physical Therapy at the Washington University School of Medicine. "And we did see that - big pulse, big error; small pulse, small error. But then we expected, just as previous theories would predict, that the adaptation in the next movement would also scale with the size of the force pulse. But it didn't - the adaptation countered the direction of the pulse but was flat with respect to the size of the pulse."

The results were published in the August 2006 issue of the Journal of Neurophysiology.

Thoroughman said the discovery raises interesting new questions in motor learning and neurophysiology and eventually could have an impact on physical therapy protocols.

"By changing environments in a specific way and by not providing the same environment all of the time, we can change the way that people learn," he said. "We're hopeful that this kind of technology can help in neurological rehabilitation so that stroke patients, for instance, could better relearn movements and reduce recovery time."

Source: Washington University in St. Louis

Robot Scout: Fly Me (Safely) to the Moon
The first attempt to land humans on the moon -- Apollo 11 -- was a triumph that almost ended in disaster. At just 400 feet from the lunar surface, with only about a minute's worth of fuel remaining, astronauts Neil Armstrong and Edwin "Buzz" Aldrin saw that their ship's computer was taking them directly into a crater the size of a football field, strewn with SUV-sized boulders. They quickly took control from the computer, flew over the crater and touched down in a smoother area beyond, cutting the engine with just 30 seconds of fuel on the readout.
Physicists Ponder Atoms Without Nuclei
You might remember learning in sixth grade science class that isotopes are atoms that have lost or gained a few neutrons, and ions are atoms that have lost or gained a few electrons. But what about an atom that has lost its entire nucleus – when essentially all that remains are the electrons whizzing around in their defined orbits?
First International Conference on Quantum Error Correction
Quantum error correction of decoherence and faulty control operations forms the backbone of all of quantum information processing. In spite of remarkable progress on this front ever since the discovery of quantum error correcting codes a decade ago, there remain important open problems in both theory and applications to real physical systems.
Photons on the Half Shell
In the realm of ultra-fast science, there's a region where photons of light can be made to dance only half steps. Here, advances in laser science are letting researchers tinker with the behavior light in an entirely new way.
Breakthrough With Ultra-Fast Xrays
Electromagnetically-induced transparency, or EIT, has been known in the visible realm for quite some time. The process is used to control such characteristics as dispersion and absorption in gases, allowing the gases to become transparent at a certain wavelength from an interacting laser. Until now, EIT has not been used in x-rays.
A good night's sleep with the flip of a switch?
The flip of a switch could become all it takes to get a good night's sleep, according to a study released Monday. Researchers at the University of Wisconsin-Madison have found a way to stimulate the slow waves typical of deep sleep by sending a harmless magnetic signal through the skulls of sleeping volunteers.
Finding Memory in Nonlinear Ionization
David Rayner and his colleagues at the National Research Council (NRC) of Canada in Ottawa have shown that when transparent solids, such as glass, are ionized with short intense laser pulses the material is subtly changed.
Physicists boost 'entanglement' of atom pairs
Physicists at the Commerce Department's National Institute of Standards and Technology have taken a significant step toward transforming entanglement--an atomic-scale phenomenon described by Albert Einstein as "spooky action at a distance"--into a practical tool. They demonstrated a method for refining entangled atom pairs (a process called purification) so they can be more useful in quantum computers and communications systems, emerging technologies that exploit the unusual rules of quantum physics for pioneering applications such as "unbreakable" data encryption.

Researchers find new learning strategy

Related stories:

News discussion: