Invisible Touch

Scientists say they have achieved a first in the development of virtual reality technology -- they felt the force of each other's touch transmitted across the Atlantic Ocean via the Internet.

Researchers from the Massachusetts Institute of Technology and at the University College in London performed an experiment in which people in labs at each university used a mechanical arm known as the PHANToM to lift what looked like a black cube in a simulated room on a computer screen. As each user manipulated the virtual object, they could feel the force being created by their counterparts through signals picked up by PHANToM and transmitted through the Web.

"As far as we know, this is the first time that touch signals have been transmitted over long distances," said Mandayam A. Srinivasan, director of MIT's Touch Lab.

The approach, which occurred for the first time May 23 and was repeated publicly for the first time last week, could eventually lead to ways to improve the use of virtual reality techniques by doctors, teachers and artists, the researchers said.

"In addition to sound and vision, virtual reality programs could include touch as well," Srinivasan said.

Atrazine Linked to Frog Decline

New evidence supports the idea that a commonly used herbicide disrupts the sexual maturation of male frogs, suggesting the chemical could be playing a role in the apparent decline of amphibians around the world.

Tyrone Hayes of the University of California at Berkeley and colleagues collected leopard frog tadpoles from eight ponds, ditches, rivers and streams in the Midwest during the summer of 2001 and found male frogs with feminine sex organs at every site where there were measurable levels of the pesticide atrazine, the most commonly used herbicide in the United States. The researchers also exposed leopard frog larvae to atrazine in the laboratory and found it feminized the males.

The research, published in the Oct. 31 Nature, is consistent with earlier findings, and with another study appearing in the November issue of the journal Environmental Health Perspectives, that suggested the herbicide may interfere with normal development by mimicking the effects of hormones.

"In light of the growing evidence that these populations are in decline, the contribution of atrazine to this decline warrants further investigation," Hayes and colleagues wrote.

The Risks of Abundance

The grandchildren of men who grew up when food was abundant may be at increased risk of developing diseases linked to overeating such as heart disease and diabetes, researchers have found.

Gunnar Kaati of the Umea University in Sweden and colleagues have been taking advantage of that country's detailed records on health, crop yields, food prices and other data that would indicate whether food was scarce or plentiful during certain periods. The group had previously studied people born in 1905 and found that those whose grandfathers lived through famine as children tended to live longer than those whose grandfathers always had abundant food.

In the new research, Kaati's team also looked at the offspring of people born in 1890 and 1920 in a part of northern Sweden and found those whose grandfathers "had been exposed to plenty of food" during key developmental years were more likely to develop diabetes and heart disease.

Although "overfeeding and overeating in families are traditions that are often transferred from generation to generation," the findings suggest that there is something in the genes at work, the researchers said.

"These are, potentially, very important findings hinting at some, as yet undiscovered, transgenerational mechanism that 'captures' nutritional information from the previous generation(s)," Marcus E. Pembrey of the University College London in England wrote in an article accompanying the research in the November issue of the European Journal of Human Genetics.

The researchers speculated that the abundance or shortage of food early in life may affect genes involved in metabolism, perhaps a gene involved in insulin, in ways that increase or decrease susceptibility to diseases related to weight.

Childhood Memories

Children don't fully develop the ability to form and retrieve long-term memories until about 2 years of age, according to new research.

Conor Liston and Jerome Kagan of Harvard University conducted an experiment involving 36 infants at 9, 17 and 24 months of age. A researcher performed and described an action, like cleaning up a table or making a rattle out of a bottle, several times and then tested the children's ability to recall the action by how well they reenacted it four months later.

The children who are now 21 and 24 months old clearly remembered the actions, whereas the 13-month-olds clearly did not.

The findings can be explained by the fact that certain parts of the brain known to be important for the formation and retrieval of long-term memories, including the hippocampus and parts of the frontal cortex, don't fully develop until the end of the second year of life.

"Our results support the popular belief that at 9 months the hippocampus and regions of the frontal cortex are not yet fully mature," the researchers wrote in the Oct. 31 Nature. "They also indicate that there is a neurobiological component to memory enhancement across the second year, contrary to early assumptions that this is entirely attributable to experience."

-- Compiled from reports by Rob Stein