| Summary: | 碩士 === 國立中央大學 === 生醫科學與工程學系 === 106 === General anesthesia is a drug-induced state in which a person’s state of consciousness is controlled through the addition and reduction of anesthetic drug. In addition to that, it makes the person, who is under the state of general anesthesia, unconscious and immobile. Hence, it is considered as an important surgical aid to prevent surgical operations wherein patients are still conscious. Although it is widely used for the said purpose, the mechanism of how consciousness is tracked under anesthesia is still poorly understood. The electroencephalogram (EEG), measured electric potentials produced by the brain, is the most feasible method in tracking brain states under general anesthesia. Using the widely used tool known as phase-amplitude coupling (PAC), described as the coupling between the amplitude of high-frequency oscillations and the phase of low-frequency oscillations, the study observed interactions of distinct patterns produced by the brain under general anesthesia. The study looked into the measurement of the coupling between the low frequency phase and the high frequency amplitude in the different stages of anesthesia. The research seeks to compare and investigate the strength of PAC in different phases.
The results showed that upon the increase of the level of exhaled anesthesia, the coupling between the phase and the amplitude gets stronger. It was found that alpha frequency amplitudes were maximal at low-frequency peaks during unconsciousness whereas maximal at low-frequency trough during consciousness period. In addition to that, the results showed that PAC is stronger during the transition from consciousness to unconsciousness and throughout the unconsciousness period. Clearly, the change in the relationship of phase-amplitude coupling between low frequency phase and high frequency amplitude throughout the different phases of anesthesia can be observed.
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