全身麻醉是由藥物引發的生理狀態，病患的意識狀態由增減麻醉藥物來控制，使得病患失去意識且不能動彈，因此，利用全身麻醉使病患失去知覺在外科手術中提供了重要的協助。儘管上述全身麻醉的用途已被廣泛的使用，但麻醉藥物如何造成意識狀態改變的生理機轉仍是缺乏了解。利用腦電波圖(EEG)測量腦部放電是追蹤全身麻醉過程中腦部狀態改變最可行的方法。相位-振福耦合強度(phase-amplitude coupling)是一種已被廣泛使用來描述訊號在高頻振盪振幅與低頻振盪相位兩者之間耦合程度的方法。本實驗發現在全身麻醉下腦波頻帶間有著特定的交互作用，並追查在不同麻醉狀態中低頻相位與高頻振福間耦合程度的變化。本研究目的為比較與探討在麻醉手術進行期間PAC的強度改變。 研究結果顯示，隨著吸入性麻醉深度的增加，相位與振幅間的耦合性也更高。我們發現在無意識狀態時 α 頻帶振幅最大值與低頻相位的極大值同時發生，而在意識清醒狀態時振幅的最大值會發生在低頻相位的極小值。結果同時顯示由意識狀態轉成無意識狀態的過程中，PAC會跟著變強並在無意識期間維持強度，低頻相位與高頻振幅之間的耦合關係在不同手術階段的轉變能清楚的被觀察到。 ;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.
