禪坐之腦部非線性動態研究

Abstract

儘管禪定帶給人類多方面身心的益處，然而相關的電生理理研究卻非常的少。本篇論文以非線性動態系統的觀點，研究禪坐對於中樞神經系統的影響。主要研究的主題是禪定腦電波訊號，同時輔以另類互補醫學儀器-ARDK的測量。ARDK量測方便，因此可以就禪坐對身體健康的影響提供一個大致的輪廓。實驗結果顯示禪坐的確可以全面促進健康狀況，尤其是在”身體能量”以及”筋骨系統”等指數。由這些結果可推論出禪坐對身體健康有長期的影響與助益。 在禪定對腦電波的影響方面，我們基於非線性動態理論發展了兩個分析參數：平均複雜度指標以及相似度指標(S)。此外，也使用傳統的線性參數：頻譜分析及相關性分析，來量化禪坐對於腦電波的影響以作為比較。我們首先分析實驗組禪定以及控制組在閉眼放鬆休息狀態，其長時間腦電波的劇本變化。藉由快數演算法，連續複雜度指標可以反映出腦部隨著不同的意識狀態之變化。結果顯示在深度禪定時，腦部動態系統呈現較高的複雜度指標。另外透過連續 ，禪坐過程中的三種不同的階段特性也得以顯示出來。 由初步的研究結果得知，資深的禪定者比起初修者較容易進入深定，禪定品質較好，伴隨有更顯著的身心變化。因此我們接著選取了23位資深的禪定者，與23位無禪定經驗者做進一步的研究。我們分別對於實驗組(禪坐)與控制組(閉眼放鬆)錄製40分鐘的腦電波，並選取在禪坐(放鬆)的前中後各5分鐘的錄製結果做複雜度指標以及頻譜分析。我們的實驗結果顯示，在禪坐的過程中前腦的alpha-1 (8-10Hz)以及後腦的beta成分的振幅較控制組增加，而閉眼放鬆的控制組則是theta增加。至於腦部動態參數複雜度指標則與beta有高度相關，也隨著禪坐過程而增加；至於控制組的複雜度指標則無顯著的變化。對照禪定者的口述推測：深定狀態時伴隨著內在光的出現，此時beta成分會增加，這種現象可以被 參數有效的反映出來。我們的結果證實，長期禪定訓練的確可以使禪定者在禪定時引發大腦皮質層的電訊號變化。 本論文接著以非線性多變數分析，探討禪坐時腦電波之空間交互作用的特性。我們以相似數指標(S)量化不同錄製點間的非對稱交互影響的強度。對於12位資深禪定者分別錄製閉眼放鬆(R)、40分鐘的禪定實(M)、以及5分鐘的守禪心輪(Z)的腦電波。在多數大腦區域，禪坐者整體上在M及Z狀態都呈現比R狀態較強的交互影響。而這種強化的趨勢尤以處於意識放空又覺知的M狀態更為顯著。至於在高頻的交互影響方面 (>13Hz)，整體而言，兩種禪坐狀態都較閉眼放鬆有較強的耦合效果。然而，這種增強的交互影響尤以處於內觀而精神統一的Z狀態更為顯著，並以後腦最為顯著。此外在Z狀態只有很少數對的電極彼此的相互影響是非對等的。這種強度相仿的結果顯示，在禪定時不同部位的大腦皮質彼此密集的交互作用及增強的相互影響，此特徵尤其以高頻的Z狀態最為顯著。我們的實驗結果證實了隨著不同的禪定階段，引起不同的大腦動態變化，這種現象可以以非線性指標得到良好的量化結果。

Orthodox Chan-Buddhist meditation brings multiform benefits to human beings but little has yet been disclosed regarding the electrophysiological characteristics of the CNS. This dissertation reports the effects of Chan meditation on CNS electrophysiological behaviors in the aspect of nonlinear brain dynamics. This work was mainly focused on the meditation electroencephalogram (EEG) signals, with the reference of a CAM instrument, ARDK. The ARDK measure might provide a feasible index for the effects of Chan meditation on the health. The results showed that Chan meditation could lead a better performance in the overall Health Condition Ratio especially in Body Energy and Musculoskeletal System. The observation allows us to infer that Chan meditation may cause a long-term effect on the practitioner to have a better health condition. Based on the nonlinear dynamical modeling, this study developed two analyzing schemes, the averaged complexity index and the similarity index (S), to investigate the effects and phenomena of meditation EEGs. In addition, the popular power spectral analysis and coherence evaluation were applied to meditation EEGs for comparison. EEG investigation started with the exploration of long-time records for both experimental (n=17) and control groups (n=16) to obtain the meditation EEG schema. Using an efficient algorithm of averaged complexity index, running complexity measures may reflect how the brain dynamics switches between various states of consciousness. The results showed that brain dynamics exhibited high indexes in deep meditation. Three different meditation scenarios have been identified from the running index chart. According to the preliminary findings of meditation scenarios, our study accordingly investigated the experienced Chan-meditation practitioners because, compared with novices, advanced practitioners might experience different physiological, cognitive, and psychological states and traits. Changes in the EEG characteristics in experienced Chan-Meditation practitioners (n = 23) during 40-minute of meditation were compared with those in the matched controls (n = 23) taking a rest for 40 minutes. complexity evaluation and spectral analysis were measured in three intervals, the first-, mid- and the last-5min sessions of Chan meditation or relaxing rest, each lasting for 5 minutes. Significant increase in frontal alpha-1 (8-10Hz) and occipital beta power was found during meditation as compared with the EEG under the rest, whereas an average increase of theta power was observed in the controls. In meditation, brain dynamics exhibited high indexes which correlated with more beta activity. Control subjects showed no significant change in complexity level. Deeper meditation state has been reported as implications of increased beta power which might probably correlate with a particular state of consciousness involving the inner-light perception. This can be more prominent by the approach of complexity estimation. Our results substantiate that long-term training with Chan-meditation does induce changes in the electro-cortical activity of the brain that are distinguishable from those observed for normal relaxation. This dissertation further presents our study on the brain interactions of experienced Chan-meditation practitioners (n = 12) varying with the meditation stages based on the nonlinear multivariate analysis. This method of similarity index (S) was used to measure the degree of possibly asymmetric coupling among multi-recording sites. Brain interactions were compared among three phases - 40-minute meditation (M), 5-minute Chakra-focusing practice (Z) and rest with closed eyes (R). Meditators exhibited, overall, stronger interactions among multiple cortical areas in meditation stages M and Z than in the R state. This enhancement was greater in the M stage when the meditator was accompanied by a thought-free and fully consciousness state. In the high-frequency band (>13Hz), the overall interdependence was also higher in both meditation stages than at baseline rest. However, the interaction strength, especially in the posterior regions, was greatest in the Z stage, which involved internal attention. Few electrode pairs were observed with significant pair-wise asymmetry in the Z state. The similarity is a possible characteristic of dense reciprocal and strong mutual interactions between multiple cortical areas during meditation - especially in the Z state in the high-frequency band. Results of this study demonstrate that profound Chan meditation induces various dynamic states in different phases of meditation, possibly reflected by nonlinear interdependence measure.