Herbal Medicine

Nasa's space shuttle Endeavour returns to Earth, landing at an air force base in California after an eventful mission.

About 150 pilot whales die in a mass stranding in a remote coastal area of the Australian island of Tasmania.

HOUSTON -- (November 30, 2008) -- Fruit flies learn better when science suppresses the activity of an inhibitory neurotransmitter, said researchers from Baylor College of Medicine in a report that appears online today in the journal Nature Neuroscience.

"If we prevent the release of GABA (gamma-aminobutryic acid) in the anterior paired lateral neurons that synapse (or send a nerve pulse to) with mushroom bodies, we see dramatic improvement in learning," said Dr. Ronald Davis, professor of molecular and cellular biology at BCM. Davis and Dr. Xu Liu conducted the experiments when Liu was a graduate student. Liu is now pursuing post-doctoral studies at the Massachusetts Institute of Technology in Cambridge. Davis is also a professor of molecular and human genetics, psychiatry and behavioral sciences and neuroscience at BCM.

In a previous report, the two had shown that too much of the cellular receptor for GABA in the mushroom bodies inhibited learning. When the levels of those receptors were reduced, learning improved. (Mushroom bodies are structures important to learning and memory found in the brains of insects such as fruit flies.)

In this study, they concentrated on the neurons that produce GABA rather than on the receptor. By reducing the release of GABA, they achieved a similar effect. They also used an optical system to produce images of the activity of the GABA-releasing cells and found that the activity of these cells was inhibited by learning."Learning occurs, in part, by inhibiting the inhibition of the GABA neurons," said Davis. So the he GABA neurons, by producing, the neurotransmitter, actually impede learning until their activity is inhibited."

The learning suppression of the GABA system probably serves as a filter on information coming into the brains of the fruit flies, Davis said. Learning occurs, in part, through mechanisms that cause the inhibition of the inhibitory neurons.

Funding for this work came from the National Institutes of Health.

The destruction of the Amazon rainforest in Brazil has accelerated for the first time in four years, officials say.

About 1,000 representatives of leading religions gather in Sweden for a summit on climate change, said to be the first of its kind.