Fluctuations and interactions between brain waves during deep and shallow anesthesia

Musizza, Bojan and Bajrović, Fajko F. and Petrovčič, Janko and Stefanovska, Aneta and Ribarič, Samo (2012) Fluctuations and interactions between brain waves during deep and shallow anesthesia. Fluctuation and Noise Letters, 11 (1): 1240018. ISSN 0219-4775

Abstract

Using gold plated electrodes, inserted into the rat's head above the dura of the left and right parietal cortex, we recorded EEG during deep and shallow anesthesia with either pentobarbital (PB) or ketamine-xylazine (KX). The fluctuations in time series were then analyzed using wavelet transforms and the spectral power was determined within 7 frequency intervals (slow wave 2, S2, 0.0067-0.0167 Hz; slow wave 1, S1, 0.02-0.19 Hz; delta, 0.2-3.9 Hz; theta, 4-7.9 Hz; alpha, 8-12.9 Hz; beta, 13-24.9 Hz and gamma, 25-34.9 Hz). In addition, the coupling strengths between individual oscillatory components during deep and shallow anesthesia were evaluated for both anesthetics. We show specific changes for both anesthetics indicating that during deep anesthesia PB reduces high and low frequency activity (0.2-35 Hz) and enhances coupling especially between delta, theta and alpha waves, while KX reduces low frequency activity (0.005 to 0.2 Hz) and enhances coupling between frequency waves alpha, beta and gamma. Our results, using two anesthetics known to block different ion channels, provide an insight into brain dynamics and could have wide implications in creating biomarkers for detecting various neurophysiological modifications, such as in Alzheimer and Parkinson's disease or Autism spectrum disorder, as well as in providing more realistic models of brain dynamics.