AGE INCREASES BRAIN COMPLEXITY

This study investigated age-related changes in the human brain functio n using both traditional EEG analysis (power spectra) and the correlat ional dimension, a measure reflecting the complexity of EEG dynamics a nd, probably, the complexity of neurophysiological processes generatin g the EEG. Assuming that the accumulation of individual experience is determined by the formation of functionally related groups of neurons showing a repetitive synchronous activation (cell assemblies), an incr ease in the number of such independently oscillating cortical cell ass emblies can be expected, despite a decline of some metabolic and memor y functions with normal ageing. Thus, the 'wisdom of old age' may find its neurophysiological basis in greater complexity of brain dynamics compared to young ages. The experimental hypothesis was that EEG dimen sion steadily increases with age. In order to test this hypothesis the resting EEGs of 5 age groups from 7 to 60 were analysed. The results confirm the hypothesis: after a jump in the brain dynamics complexity during puberty a linear increase with age is observed. During maturati on (7-25 years), the maximum gain in complexity occurs over the fronta l associative cortex.