Specific EEG Markers of Pain Processing Under Anesthesia in Rats

This work focuses on intricacies of interplay between pain-induced and urethane-induced EEG activity. We estimated physiological activity of rats' somatosensory cortex under urethane-induced anesthesia both before and after presenting pain stimulus in the form of a formalin injection into the left hindlimb. Analyzing such parameters as EEG amplitude, proportion of amplitudes between left and right somatosensory cortices, spectral entropy and other, we observe significant differences between EEG under anesthesia with and without pain stimulation. Moreover, we show different cortical responses to said stimulation during different phases of urethane anesthesia. Presented observations may be useful for EEG analysis of physiological state in both humans and animals under general anesthesia. Furthermore, said results shed light onto basic principles of pain processing, suggesting possible applications in further neurogenic pain research as well as in fundamental physiology.