Tuesday, March 23, 2010


New findings by a team of University of Maryland researchers may lead to new, non-invasive technologies for portable brain-computer interface systems. Such technologies potentially could allow people with disabilities or paralysis to operate a robotic arm, motorized wheelchair or other prosthetic device using a headset with scalp sensors that send signals from the brain to the device.

Led by Maryland's Jose Contreras-Vidal, an associate professor of kinesiology, the team of neuroscientists successfully reconstructed 3-D hand motions from brain signals recorded in a non-invasive way. Their results are published in the March 3 issue of The Journal of Neuroscience. In this study the scientists placed an array of 34 sensors on the scalps of five participants to record their brains' electrical activity, using a process called electroencephalography, or EEG.

Volunteers were asked to reach from a center button and touch eight other buttons in random order 10 times, while the authors recorded their brain signals and hand motions. Afterward, the researchers attempted to decode the signals and reconstruct the 3-D hand movements.

"Our results showed that electrical brain activity acquired from the scalp surface carries enough information to reconstruct continuous, unconstrained hand movements," said Contreras- Vidal, who also holds appointments in bioengineering, the university's Neuroscience and Cognitive Science Program and its Center on Aging.

"Our ground-breaking research opens the possibility for the development of assistive devices for the neurologically-impaired or disabled. We are currently working with robotic arms and wearable upper limb exoskeletons [as shown in above image], but there are a number of steps before this technology can be applied clinically," said Contreras-Vidal.

Prior to this study, researchers have used non-portable and invasive methods that place sensors inside the brain when reconstructing hand motions.

Vidal, with Maryland colleagues Trent Bradberry, a graduate student in the Fischell Department of Bioengineering and Rodolphe Gentili, a research assistant professor of kinesiology, found that one sensor in particular provided the most accurate information. The sensor was located over a part of the brain called the primary sensorimotor cortex, a region associated with voluntary movement. Useful signals were also recorded from another region called the inferior parietal lobule, which is known to help guide limb movement. The authors used these findings to confirm the validity of their methods.

A release from the Society for Neuroscience said this study has implications for future brain-computer interface technologies and for those already in existence. An expert unaffiliated with the study, Jonathan Wolpaw, MD, of the New York State Department of Health's Wadsworth Center in Albany, was quoted. "It may eventually be possible for people with severe neuromuscular disorders, such as amyotrophic lateral sclerosis (ALS), stroke, or spinal cord injury, to regain control of complex tasks without needing to have electrodes implanted in their brains. [This] paper enhances the potential value of EEG for laboratory studies and clinical monitoring of brain function," said Wolpaw.

The findings also could lead to improvements in existing EEG-based systems that are designed to allow movement-impaired people to control a computer cursor with their thoughts. Such systems now require that users undergo extensive training. However, according to Contreras-Vidal more effortless control could be achieved with such systems and the length of training required to use them could be reduced using the methods in this study.

(Photo: U. Maryland)

University of Maryland

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