Monday, July 17, 2006; A08

Brain to Computer to Action

An electronic array implanted in the brain of a 25-year-old man paralyzed from the neck down has allowed him to use his brain signals to take actions such as opening e-mail and manipulating a computer mouse, scientists report.

While such brain-to-computer devices are still far from being able to mimic what humans can do in terms of fine control, precision and speed, they offer hope that people with spinal cord damage and other serious problems might one day regain important aspects of autonomy and functioning.

Scientists at Massachusetts General Hospital and other academic institutions said the system developed at Cyberkinetics Neurotechnology Systems Inc. is remarkable not just as a technological marvel but also because it shows that the brain is capable of sending out signals years after a severing of its connection to the limbs.

Shortly after the device was installed and calibrated, the patient was able to play a simple video game, read e-mail and control a television set.

A report on the case was published last week in the journal Nature, along with an article detailing a technique that seeks to convert an even earlier stage of brain activity into action. By picking up brain signals at the level of intentions instead of waiting until the brain begins to direct physical movement, scientists at Stanford University hope to allow patients one day to complete actions without even having to think about the action itself.

-- Shankar Vedantam

The mammals who make the longest overland migration in the continental United States may disappear from the ecosystem of Yellowstone and Grand Teton national parks, according to a study in the latest issue of the journal Biology Letters.

A herd of pronghorn antelope, which for more than 6,000 years have journeyed at least 400 miles between their calving and wintering grounds, is being squeezed out of its migration routes by development and human disturbance outside the parks. Scientists from the Wildlife Conservation Society and the National Park Service found that six of the antelopes' eight migration corridors in and out of the Yellowstone ecosystem have disappeared, and the animals must now pass through bottlenecks that are not much wider than a football field.

"It's amazing that this marathon migration persists in a nation of almost 300 million people," said lead author Joel Berger, a researcher at the Wildlife Conservation Society. "At the same time, the migration is in real trouble and needs immediate recognition and protection."

While the herd is small at this point -- it numbers between 200 and 300 -- the researchers wrote that saving its migration route would be "more than symbolic" and that if it is obstructed, "whether by petroleum development, housing or other factors, an entire population from a national park could be eliminated, leaving a conspicuous gap in the ecology and function of native predator-prey interactions."

-- Juliet Eilperin

Astronauts traveling to the moon and beyond face an unexpectedly large risk of bone loss as a result of cosmic radiation, new research on mice suggests.

Space scientists have long known that weightlessness causes atrophy of bones and muscles, and researchers had suspected that radiation could also have an effect. But the mouse experiment found that even limited exposure to certain kinds of radiation caused a loss of 39 percent of the spongy portion of the inner bone.

"We were really surprised to find that degree of bone loss," said lead researcher Ted A. Bateman of Clemson University, whose findings appear in the online version of the Journal of Applied Physiology. He said that the radiation primarily degraded the spongy inner "trabecular" portion of the bone rather than the hard outer "cortical" area.

Bateman said that the results of a mouse study cannot be directly applied to people but that they are consistent with research findings that women who receive radiation treatment for cancer are substantially more likely to experience fractures because of bone loss. "I think this means that the combination of radiation and weightlessness pose some real biomedical problems for humans living for long periods in space," he said.

While astronauts have experienced some bone loss, it has not been dramatic. Bateman said this may be because, except for the moon missions, the astronauts remained inside Earth's magnetic field, which protects against the cosmic radiation that is likely to be most damaging -- protons and heavy ions.

Much of the U.S. scientific effort on the international space station is now focused on how to enable astronauts to stay in space for prolonged periods.

-- Marc Kaufman