Dynamical organisation of the human visual system revealed by lifetimes of activation traces.

Magnetic source imaging reveals a dynamical organisation of visual cortical areas suggesting that the participation of local memories is an essential component of visual information processing. Response recovery studies provide evidence that each responding cortical area supports a memory function with a well-defined lifetime. The areas fell into two 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 areas with lifetimes ranging from 7 to 30 s. Also, within each group the areas responding later tended to have longer lifetimes.