Thalamo-cortical mechanisms of the observed specific changes in frontal and occipital EEG rhythms during propofol-induce sedation
© Hashemi et al. 2015
Published: 18 December 2015
The power spectral analyses reveal that the alpha power originates from the cortico-thalamic relay interaction, which is associated with a constant time delay around the inverse of peak frequency in alpha band. It is shown that as the concentration of propofol increases, dependent on the potential values of the resting state of the system, it causes an increase or decrease in the gains function within the thalamo-cortical loop what then results in an increase or decrease in the spectral power in the alpha band over frontal and occipital regions, respectively. The model indicates the importance of multiple resting states in brain activity. Moreover our findings demonstrate that the emergence of delta power results from the increased GABAergic inhibition into the thalamo-cortical system.
Our results reveal that the specific observed changes in EEG rhythms can be reproduced with and without the propofol effect in cortical cells. This finding points out the importance of thalamus for neural effects under anesthesia sedation and simplifies the model under study. By reducing the dimensionality of the model we are able to obtain some inequality conditions for the stability of the system. In addition, the analytical tractability of the model allows us to obtain further insight into the mechanisms underlying the characteristic spectral features seen during anesthesia sedation.
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