Elektroencefalograficzne badania rytmiki dobowej snu i czuwania u zwierząt

Abstract

By means of the electroencephalograph (an Elema Schonander minograph) bioelectrical activity of the brain (frontal and sincipital cortex and the nucleus caudatus) was recorded. Besides the EEG, activity of the antigravitational muscles of the neck (electromyogram - EMG) was also recorded. EEG and EMG were recorded at different times of the day (and night), i.e. at 6,12,18 and 24 hours, in physiological conditions, after injecting (0,5 ml/kg of body weight) 0,9% NaCL solution and after electrical stimulation with the electric current the nucleus caudatus in five rabbits. The nucleus caudatus was stimulated with the electric current of 50 c/sec frequency during the time of a single impulse of 0,5 m/sec tand the tension of 8 volts. The stimulating time of the nucleus caudatus was 5 seconds. The analysis of the obtained data shows that the electroencephalographical and behavioural patterns of sleep and vigil which were recorded in the rabbits are of cyclic character. All the recorded structures of the brain, i.e. the frontal and sincipital cortex and the nucleus caudatus seem to be connected with the mechanisms regulating the processes of sleep and vigil in rabbits. It is probable that apart from the diurnal cycle of sleep - vigil, there also appears in rabbits an ultradiurnal, basic resting — activating cycle (BRAC) lasting about 35 - 40 minutes. The sensitivity of the examined structures of the central nervous system to the experimentally applied stimuli (intravenous injection and electrical stimulation of the nucleus caudatus) varies and reaches its maximum in the nighttime. Apart from the differences which were found, a number of similarities was observed in the reactions of the structures in question to the applied stress factors. At the same time one should emphasize that the common practice of comparing results obtained at different times during the day is unjustified in the light of the above data. The effects of the electrical stimulation of the nucleus caudatus indicate the participation of this structure in the inhibitory mechanisms of the central nervous system and suggest its influence on the diurnal rhythm of sllep and vigil in the rabbit.