In Brief; November 1998; Scientific American Magazine; by Leutwyler; 3 Page(s)
Unforgettable? Using advanced functional magnetic resonance imaging (fMRI), two groups of scientists have captured the first images of memories being formed within the brain. Randy L. Buckner of Washington University and his colleagues at Harvard University and Massachusetts General Hospital measured brain activation in young adults as they completed verbal tasks. Later the subjects were asked which words they remembered. James B. Brewer and his colleagues at Stanford University conducted a similar investigation, asking subjects to recall photographs. In both studies, higher levels of activity in the prefrontal and parahippocampal cortices--regions long thought to be involved in encoding memory--corresponded with stronger memories.
Winding the Master Clock The big wheel keeps on turning all right, but not at the same speed. The earth¿s rotation is actually slowing down. Thus, on December 31 the U.S. Naval Observatory, working for the International Earth Rotation Service (IERS), will add a leap second to the Coordinated Universal Time, the basis for world timekeeping. It is the 22nd leap second added since 1972, when the IERS decided to let atomic clocks--accurate to within a billionth of a second a day--run independently of the earth, which as a clock is only good to about one thousandth of a second a day.