[Discriminant analysis of graphic elements of the EEG. Application to the detection of episodes of diffuse spike-waves]. / Analyse discriminante des grapho-elements de l'EEG. Application a la detection des bouffees de pointes-ondes diffuses.

A database of EEG information was collected from EEG recordings performed in epileptic patients with diffuse spike-wave complex discharges. Normal activity, spike-waves, slow waves and artefacts were mixed up in these recordings. The analysis of EEGs stored in the database was performed, channel by channel, through a 2.56 s moving window. For each so defined EEG sequence, a set of 22 variables chosen for their discriminatory power was computed. A subset of 8 highly discriminating variables was selected by the means of a stepwise discriminant analysis. Each class of the learning set contained 40 up to 100 EEG sequences. A classifying algorithm that takes into account zones of uncertainty is proposed. It has been evaluated on a test set which was composed of 1981 EEG sequences issued from 15 different patients. The results have been checked by two neurologists. The agreement rate between each of them and the proposed algorithm was more than 92%; this result is comparable to the agreement rate between the two neurologists (94%). A contextual analysis algorithm, using bi-dimensional smoothing techniques, allowed to improve the agreement rates which exceeded 94%.

[A minicomputer system that extracts evoked responses from the E.E.G]. / EVøQ: systeme configurable de stimulation automatique et d'enregistrement des potentiels evoques moyens sur mini-ordinateur.

EVøQ is a minicomputer system that enables one to extract average evoked responses from the E.E.G. from a large number of analog channels, and can, therefore, be oriented towards a topographic study of the responses. It allows high-frequency sampling of the signal, in order to make possible a study of the brain stem evoked responses. This system consists of three programs: a configuration-editor which allows a pre-configuration of several kinds of experiments; an acquisition program, of monitoring, calibration, signal processing and automatic control of the stimulators; finally, a management and processing program of the resulting files.