DYNAMICAL ORGANIZATION OF THE HUMAN VISUAL-SYSTEM REVEALED BY LIFETIMES OF ACTIVATION TRACES

Magnetic source imaging reveals a dynamical organisation of visual cor tical areas suggesting that the participation of local memories is an essential component of visual information processing. Response recover y studies provide evidence that each responding cortical area supports a memory function with a well-defined lifetime. The areas fell into t wo groups, the earliest in occipital lobes with lifetimes ranging from 0.1 to 0.6 s, and the later ones in temporal, parietal, and frontal a reas with lifetimes ranging from 7 to 30 s. Also, within each group th e areas responding later tended to have longer lifetimes.