Brain electrical activity in depression described by equivalent dipoles.

The majority of neurophysiological investigations of waking EEG in depression have been relatively disappointing. Since the topographic distribution of brain electrical activity over the scalp in the frequency domain (FFT-power) varies considerably when choosing another site for the reference, it is not surprising that various investigators reported contradictory results. The aim of the present study was to investigate differences in brain electrical activity in a sample of depressed patients as compared to healthy subjects using a newly developed method called FFT approximation. As the major finding healthy subjects and depressed patients demonstrated significantly divergent patterns of localization between frequency bands in the anterior-posterior direction. The investigation suggests that a non-invasive neurophysiological methods gives results which are comparable to those obtained by other functional and structural imaging methods in depressive illness.