ON THE INTERCORRELATION OF SOME FREQUENCY AND AMPLITUDE PARAMETERS OFTHE HUMAN EEG AND ITS FUNCTIONAL-SIGNIFICANCE - COMMUNICATION II - NEURODYNAMIC IMBALANCE IN ENDOGENOUS ASTHENIC-LIKE DISORDERS

In 67 borderline psychiatric patients suffering from schizotypal/slowl y developing schizophrenic disorders and 18 patients suffering from cy clothymia, the factor structure of the period (interval-amplitude) par ameters of the EEG proved to be similar to that obtained in normal sub jects during mental activity and reported in part I (Lazarev, Int. J. Psychophysiol., 28 (1998) 77-98). However, 51 patients with schizotypa l disorders with a predominance of asthenic-like symptomatology, chara cterized by mild thought disorders with difficulty in focusing attenti on, were distinguished from normal subjects, cyclothymic patients and other patients of schizotypy without well-defined asthenic symptoms by significantly increased values of EEG Factor II which was positively related to the index-presence in epoch, frequency and regularity of lo w-amplitude beta-waves, and reduced values of an EEG Factor III which was positively correlated with mean alpha-period and theta-index. Acco rding to normative data (part I; Lazarev, Int. J. Psychophysiol., 28 ( 1998) 77-98), this probably reflects a neurodynamic imbalance between an excess of 'cortical excitation' (Factor II) and a deficit of 'activ e selective inhibition' (Factor III). This imbalance appears to be opp osite to the changes in values of these factors found in normal subjec ts during focusing attention and motor automation, when compared with relaxed wakefulness. The functional properties of-Factors II and III a scribed on the basis of psychological testing suggest that such an imb alance could reflect a predominance of successively organised associat ive mental processes over the selective inhibition of irrelevant assoc iations. This could cause difficulties in voluntary attention, mental automation and in the performance of simultaneous mental operations. I n most cases, there was no difference in Factor I which was positively related to the index, amplitude and regularity of alpha-activity and wave amplitudes in other bands, and negatively related to the indices and mean periods of delta-and theta-waves, the factor presumed to depi ct 'general activation'. (C) 1998 Elsevier Science B.V. All rights res erved.