On some EEG patterns in children and adults.

The EEGs of 76 children (6--9 years of age) were classified into five types for the occipital regions (O1 and O2) and into seven types for the central regions (C3 and C4) by the method of EEG pattern discrimination (Sato, Ono et al., 1977). The five types of EEG patterns observed in the occipital regions were: (1) low frequency alpha wave of about 8--9 Hz, (2) Hz alpha wave, (3) low frequency alpha and theta wave, (4) 10 Hz alpha wave and theta wave and (5) irregular wave patterns, while two more types, (6) the low pass and (7) theta wave types, were observed in the central regions. These same types were also observed in the EEGs of 41 adults (20--25 years of age). The amount of difference between the above five and seven types in children and adults were obtained by the generalized (Mahalanobis') distances. In the occipital regions, the percentage frequency of the alpha wave type was the highest followed by that of the alpha and theta wave type, while the frequency of the alpha and theta waves type was the highest in the central regions, followed, next and third in order by the low pass type and the alpha type, respectively.