Free Republic

The brain cranks out memories near its center, in a looped wishbone of tissue called the hippocampus. But a new study suggests only a small chunk of it, called the dentate gyrus, is responsible for “episodic” memories—information that allows us to tell similar places and situations apart. The finding helps explain where déjà vu originates in the brain, and why it happens more frequently with increasing age and with brain-disease patients, said MIT neuroscientist Susumu Tonegawa. The study is detailed today in the online version of the journal Science.

The original home of the world's most famous space rock, the Allen Hills Martian meteorite, has now been identified, thanks to data from the orbiting spacecraft Mars Global Surveyor and Mars Odyssey and a better understanding of cratering dynamics. The rock, called ALH84001, has been the subject of intense study ever since 1996 when scientists from NASA's Johnson Space Center startled the world by reporting that fossilised microbial life might be embedded inside it. The rock, which formed at the very dawn of the solar system 4.5 billion years ago, was blasted from the surface of Mars around 17 million...