The amount of energy in the electro

The amount of energy in the electroencephalogram (EEG),
indicates electrical activity in the cortex that shows systematic spurts
that closely parallel the spurts observed in optimal levels for cognitive
development, In addition, connections among cortical regions, which
are measured by EEG coherence (the correlations of wave patterns
between regions), demonstrate qualitative shifts at the same age
periods. The ages for these two kinds of brain changes are remarkably
similar to those of the cognitive levels.p3.