Variation in length of alpha waves reveals how forebrain activity is organized

Background The cerebral cortex is composed of functional units known as columns. The “two levels” hypothesis states that the activity in a column is either at a high level or at a normal, relatively low level. Measurements indicate that the duration of the high activity in a column is around 450 ms. The number of highly active columns is often 4–5. These data are from previous studies on alpha waves in electroencephalograms. The idea is that...