Discriminant parameters representing cerebral cortical function during anoxic XXXX investigations.

@entity302 @entity519 @entity95 @entity4095
In order to quantify the effect of specific drugs on the cerebral cortex an "in vivo" model has been developed for the induction and the observation of anoxic @entity519 . @entity95 are used as test animals. Sensors for the assessment of local parameters are chronically implanted: ECoG electrodes are applied; @entity4095 electrodes are inserted into the cortical tissue. The derived somatosensory evoked potentials are used for evaluating the cerebral cortical function. Animals are cannulated with a tracheal tube, curarized and artificially ventilated. Anoxic @entity519 , controlled by a special purpose microprocessor system, may then be induced and repeated in a reproducible way. During the experiments local ( @entity4095 , ECoG, SEP) as well as general parameters (ECG, heart rate, systemic blood pressure, rectal temperature) are recorded and stored on analog magnetic tape as well as digitized with the microprocessor system. The cortical @entity4095 is measured with a polarographic method, the SEP's are obtained on-line by time coherent averaging and the ECoG states (e.g. @entity302 during @entity519 ) are derived by using band-pass filters and rms detectors. Off-line the signals ( @entity4095 , heart rate, mean systemic blood pressure, temperature) are standardized and represented together with parameters derived from ECoG and SEP. SEP-waveform parameters indicating intensity (norm) and similarity with a reference SEP signal (correlation value) are used. The measuring and processing method is still being optimized; special attention is being paid towards the quality of the calculated SEP's which are to be used for the quantification of the cortical function during reference, @entity519 and recovery period. As such, in order to improve the signal-to-noise ratio of the SEP's and, consequently, of the derived parameters, ECoG signals are digitized off-line and subjected to a preprocessing, implying filtering and spectral analysis procedures.
