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A critical analysis of quantitative pharmaco-electroencephalography begins with parametrization into variables. The determination of frequency bands according to clinical criteria should be reconsidered. Alternatives may be the determination of factor scores or the definition of frequency bands based on factor analysis. If the latter procedure is used, the clinical alpha-band is subdivided into a lower (alpha 1F = 8,5-10.5 HZ) and an upper (alpha 2F = 10.5-12.5 HZ) part. Furthermore parts of the clinical theta-band (and the delta-band are combined into the delta F-band (1.5-6.0 HZ), for awake healthy volunteers with an occipital alpha-rhythm. Existing concepts of vigilance for the awake stages are not contradictory to the following observations: the factor structure of EEG relative power spectrum variables shows a negative correlation of slow alpha-frequencies with those in the delta F- and beta 3F-band. There is also a negative correlation between slow and fast alpha-wave relative power values.

"Equipotential" doses of lormetazepam, triazolam and flunitrazepam were tested regarding their influence on K-complexes, sleep spindles and rapid eye movements. The receptor affinity was used to determine the equipotency. In this respect triazolam, lormetazepam and flunitrazepam show a relationship of 1:2:4. Lormetazepam, however, showed only slight changes of the three neurophysiological parameters even when given as double dosage. Triazolam and flunitrazepam reduce K-complexes considerably, increase sleep spindles enormously and reduce REM activity markedly; both substances suppress the first REM period, flunitrazepam even the second one. All three of the benzodiazepines have the same effect on the dissociation of K-complexes and sleep spindles; epochs with K-complexes or sleep spindles are favored compared to epochs with K-complexes and sleep spindles. The general reduction of K-complexes and the increase in sleep spindles can be interpreted as a sleep protective function. When deciding on the dosage, however, REM-suppression should be used as a guide since it has the strongest effect on the cyclic structure of sleep which nowadays is considered to be the safest evidence of well balanced sleep behavior.

Many persons show two different types of delta-activity during synchronized sleep; these can already be differentiated visually as follows: one is located over the anterior brain areas, has a high frequency and is monomorph, the other one is located over the posterior brain areas, has a low frequency and is polymorph. However, both rhythms overlap considerably regarding their cortical distribution. The high high frequency delta-activity usually ranges from 1.5-2.9 Hz with a maximum at 2Hz; the one with low frequency ranges from 0.1-1.4 Hz with a maximum at 0.9 Hz. The interhemispheric coherence of the delta-activities is high with 0.7-0.9; for the anterior regions it is slightly higher than for the posterior ones. The intrahemispheric coherence is low, as was to be expected, and it is less than 0.3.

Visual evoked neuromagnetic fields were recorded after stimulation of the right and left foveal half-field and of the right lower and upper quadrant. A contralateral topography of the dominant complex of the visual evoked field was measured on the skull after right and left half-field stimulation. After switching from the right half-field stimulation to the stimulation of the right quadrants we observed large individual differences in our subject group. A possible morphological explanation is that the more elementary stimulation in the quadrants is connected with a greater number of dipole orientations as compared with the less elementary stimulation in the half-fields.

Both pentazocine and buprenorphine are hypnoanalgetics of the agonistic-antagonist group. They suppress the inhibitory effect of fentanyl upon the central nervous system. They show also secondary their own inhibitory properties (fig. 8). The agonistic-antagonists can be further divided in excitants (like pentazocine) and non-excitants (buprenorphine).

Pentazocine dependencies are rare. In a period of 5 years, 60 were notified. The majority of these were not dependent. Of 46 utilizable notifications, 38 were false, 5 had taken pentazocine only temporarily or not at all. 19 received it for chronic or recurrent pains, 13 were polytoxicomaniacs, and 1 patient could not be classified. Only 8 cases could be referred to as pentazocine-dependent. The dose for addicts and polytoxicomaniacs was 11 ampoules daily on the average, almost three times as high as that for patients with painful diseases. Pentazocine dependencies are considerably less of a problem than those of opiates used up to now: withdrawal symptoms are slight, neglect and social dangers need scarely be considered. "Users" generally only turn to pentazocine when a painful disease supervenes. Dependency practically never occurs with oral administration.

Patients with suspected seizure disorders frequently show graphoelements which can be interpreted as the expression of a disposition for epilepsy. These sharp vertex elements were evident in 54 out of 719 short term sleep recordings, more often in children than in adults. 49 times they coincided with typical epileptic discharges such as sharp waves, spikes or spike waves in the same recording.

For the classification of sleep stages, international standards based on visual EEG analysis have been established and are in common use, although we are well aware of their limitations. Several authors have suggested different procedures for classifying the stages of vigilance during the waking stages. No universally accepted paradigm, however, has yet been developed. The proposed vigilance classification procedures are based either on visual or automatic analysis procedures. Even though the EEG activity and patterns that reflect vigilance changes have been identified and described as indicators of the state of alertness, opinion is divided on how these should be combined in a vigilance classification rule. Automatic methods, on the other hand, have up to now used only part of the information available, the relationship of which to vigilance indicators has only been partially explored. The COMSTAT (Dept. of Computation and Statistics, AFB-Arzneimittelforschung, Berlin, FRG) rule combines visual and automatic analysis procedures. Different vigilance-dependent EEG patterns, such as the proportion of occipital background rhythm under resting conditions and its replacement by either faster or slower waves, the frequency range of the occipital rhythm and the anteriorization phenomena, have been used as information for a latent class analysis (LCA5) with 5 classes (stages of vigilance). There is a high correlation between the results of the LCA5 with visual classification rules made by experts. Using a robust discriminant analysis function which takes into account prior probabilities of the classes, and with a linear cost function for misclassification, an automatic rule with power spectrum variables was fitted to the results of the LCA5. Reclassification and split-half classification showed a high overlap between LCA5 and automatic classification. The result of this procedure is a new vigilance classification rule that is based on an objective mathematical rationale for the combination of different vigilance-indicative EEG activities and patterns but which can be applied to power-spectral estimators in an automatic EEG analysis procedure.

Polysomnographic EEGs were recorded from 12 adult volunteers between the ages of 20 and 50 years. They were given placebo, pentobarbital, carbromal, methaqualone, flunitrazepam, lormetazepam and triazolam. The visual evaluation was aimed at finding periodic sequences of centro-parietal sleep spindles at 13-15/s. Four consecutive spindles following each other regularly were defined as the shortest sequence. Placebo showed the following results: a considerable interindividual variance with 2 to 6 such sequences on the one hand and 25 on the other hand for each night. sequences with six periodically consecutive spindles dominated; the longest sequence contained 15 spindles. the inter-spindle distance was 4 seconds (m: 4.09; mean 4.14 s). All hypnotics caused an increase in periodic spindle sequences. Volunteers with a low tendency to have periodic spindle sequences remained at the lower end of the scale when taking hypnotics. Hypnotics increased the amount of longer spindle sequences, however, the average was still at sequences of 4-11 consecutive spindles. The inter-spindle distance became longer with all hypnotics; 4.34 s (carbromal) up to 4.58 s (flunitrazepam). Volunteers with a low tendency to have periodic spindle sequences showed shorter distances between spindles vice versa. Benzodiazepines do not reveal any characteristics due to their pharmacokinetic structure.