Electroencephalographic recordings of physiological activity of the sheep cerebral cortex.

This paper presents the physiological activity of the cerebral cortex in sheep in electroencephalo- graphic findings. The study was performed to evaluate and improve understanding of brain monitor- ing methods in freely moving animals without the use of any anaesthetic methods during the acquisi- tion stage. The aim of the study was to determine the physiological activity of the cerebral cortex in animals in a sheep model (using clinically healthy Polish Merino rams, aged 1 yr.) to determine its clinical EEG protocol. The EEG was registered using an in-lab EEG device as well as ambulatory systems (Holter EEG). The bioelectrical activity of the sheep cerebral cortex was recorded using gold disc and needle electrodes placed on experimentally determined locations on the scalp. The main finding of this study was the rhythmic EEG activity of the sheep brain in wakeful and conscious states (eyes open). The rhythm was bilaterally synchronous and determined a basic pattern in the registra- tion of physiological activity of the cerebral cortex. The acquired rhythm may correspond to the theta rhythm in humans, which is a normal activity controlled by the hippocampus. This background activity comprised intermittent episodic slow waves and synchronous beta waves.