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This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Anesthetic techniques using different substances with anesthetic properties have been used since antiquity. However, even today, it is not known exactly how these anesthetics work, if there is a common site or if their action is multi-level. In this article we present the latest theories regarding the mechanism of anesthetics' action. Thus we will refer to the action of anesthetics on neural networks, we will discuss the fractal theory of consciousness as well as the soliton model and the theory of the action of anesthetics on the cellular cytoskeleton.

Background and aims. The purpose of this study is to assess the frontal and parietal ECoG spectrum (gamma range) changes during isoflurane and combined xenon-isoflurane anaesthesia in rats.Methods. Experiments were carried out on four adult male Sprague-Dawley rats (250-300 g). The anaesthesia was induced with isoflurane and maintained with isoflurane and a xenon-isoflurane mixture. The rats were maintained at two different anaesthetic depths: light (isoflurane anaesthesia) and deep (isoflurane and xenon-isoflurane anaesthesia). The frontal and the parietal cortical activity was assessed by computing the median frequency, spectral edge frequency and functional connectivity between these two areas during light and deep anaesthesia.Results. We noticed a decrease in cortical connectivity under deep isoflurane anaesthesia and an increase in connectivity under deep xenon-isoflurane anaesthesia. Moreover, during xenon-isoflurane anaesthesia, a trend of regularity of electro-cortical activity was present compared with isoflurane anaesthesia.Conclusions. Xenon-isoflurane deep anaesthesia demonstrated a series of specific ECoG features regarding frontoparietal functional connectivity (gamma range connectivity increase) and regularity of the electrocortical activity compared with isoflurane anaesthesia.

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.