[Consciousness and the electroencephalogram]

In the course of 12 years the authors subjected to clinical EEG and stereo-EEG (SEEG) 72 patients (66 epileptics with the diagnosis of psychomotor epilepsy and grand mal) and six psychotic patients suffering from schizophrenia. With the exception of five epileptics and two psychotic patients all subjects had epileptic foci in the amygdalohippocampal complex (AHK). After coagulation of these foci marked improvement of the fits and the mental state occurred in half the patients. During EEG and SEEG recording the authors used different activation methods (hyperventilation through the nose and mouth, sleep, listening to music) and above all direct electric stimulation (ES) of one of the AHK. Secondary epileptic foci had, as a rule, more spikes and a lower threshold for ES than primary ones which contained more delta and slow theta waves. The ES led as a rule to an emotional response, such as anxiety and fear, more rarely to illusions, depersonalization and oneiroid hallucinations and twice to a hedonic response of non-sexual character. The purpose of ES was to assess the site from where it is possible to start the original aura or typical parox. The authors considered these foci, consistent with data in the literature, as the leading focus and it was subsequently coagulated. The authors investigated the reactivity and vigility by the patient's response to sound (the patient had to press a button) and by an interview with the patient. It was revealed that in isolated discharges of the spikes and waves in the scalp electrodes, i.e. in the neocortex, reactivity is lacking. In isolated discharges in the AHK the reactivity was satisfactory, but as a rule anxiety developed. It is thus possible to divide consciousness into emotional consciousness with its site in the AHK, i.e. in the limbic system, and rational consciousness which is a function of the neocrotical system. Congenital changes of consciousness such as vigility or sleep are described as "states" of consciousness. The rational or emotional aspect of behaviour is described as "type" of consciousness. Under normal conditions the states of consciousness alternate periodically and are sharply defined, the types of consciousness are closely linked and are difficult to separate. Under pathological conditions the "states" of consciousness differ less markedly and the "types" of consciousness are in dissociation. Thus obnubilation, depersonalization, illusions, pathic affects etc. develop, as a rule as part of the epileptiform or psychotiform syndrome.