[Brain activation levels and the significance of the stage B(I) indices in neuroses].

Two forms of neuroses--neurasthenia and hysteria--show statistically definitive differences in the EEG patterns. In the initial EEGs of neurasthenic patients, as a rule, more or less marked alpha-rhythm is preserved, whereas the EEG in hysteria in most cases consists of low amplitude fast frequencies ("flat" EEG) and only in 30-35% cases short episodes of alpha-waves can be recorded. In the course of medical treatment the index alpha often increases and the EEG gradually obtains normal features. One of the most favourable signs of convalescence is the renewal of the ability to develop the phase of drowsiness with the stage B in the EEG, during which the outburst of alpha-waves is recorded as a reaction to stimulation.