禪坐中心血管系統及中樞神經系統電生理現象之研究

Abstract

本篇論文在研究禪坐對於心血管系統，以及對於中樞神經系統的影響。在評估心血管系統的效應中，我們使用了血液壓力波的四種參數來量化禪坐對於血管系統的效果，這四種參數包括了T波的上昇斜率，以及T波、V3波谷以及D波的正規化的高度。我們的實驗結果顯示，禪坐會加強心臟的搏出能力，得到較佳的動脈順應性，降低血管的阻塞，並強化動脈彈性以及主動脈瓣膜的功能。這些觀察結果可推論出禪坐的確可以促進心血管系統的相關特性。 禪坐者在禪坐過程中，常會體驗到有內在光芒的出現，為了研究此一普遍現象，我們設計了閃光視覺誘發電位實驗。在禪坐(放鬆)的前中後，我們對實驗組(控制組)受測者施以閃光刺激並蒐集視覺誘發電位。我們的實驗結果顯示在禪坐的過程中，後腦(Oz)位置上較晚的視覺誘發電位成分N3-P3以及P3-N4，其振幅會較禪坐前降低，但是對於控制組(放鬆)而言，這些成分的振幅卻是增大的。此外，這些成分在中腦與前腦的振幅，在禪坐過程中是增加的，在休息中則是減少的。而某些成分的潛時(latency)在休息中是延長的，而禪坐中則是沒有太大的變化(P2則有變化)。根據我們的發現，禪坐過程對於視覺神經系統以及大腦皮質層的特定效應，和單純閉眼休息造成的效果是不一樣的。 在第四章中，我們探討了禪坐腦電波對於alpha波的空間聚集效果，並有了初步的結果。我們分別對於實驗組(禪坐)與控制組(閉眼放鬆)錄製腦電波，並使用小波分析方法對多頻道腦電波進行萃取alpha波的工作。我們再對正規化的alpha能量向量使用模糊分類演算法進行分類，以探討不同的空間分佈特性。分類過程中，我們對各群中心的模糊關係值向量進行相似度比對，以找出最佳的分類數。我們的結果顯示，前腦alpha活動發生的機率與禪坐的階段有關。從結果中可證實，禪坐過程中會產生三種空間-時間變化的分佈類型，而這是由於禪坐過程中的三個階段所產生的。此外，這兩組的後腦alpha活動也有不同的趨勢，控制組在禪坐過程中，後腦alpha的能量隨著時間呈現遞減的現象，但是實驗組則的後腦alpha一直呈現低於平常準位的現象。這些研究結果顯示，禪坐的過程大致上會分成三個階段，而各個階段對於alpha調變的機制有所差異。 在第三與第四章中，我們觀察到禪坐過程中，前額alpha有增加的趨勢，且視覺誘發電位與閉眼休息的情形下，也有不一樣的變化；因此我們設計了一種新的實驗，使受測者在相同的背景腦電波的條件－前額出現由alpha波主導的情況下，我們才對受測者施予閃光刺激。我們觀察了實驗組(禪坐者)與控制組(一般未練習禪坐者)兩者之間視覺誘發電位的差異，結果顯示，在禪坐中時，Cz 及Fz的位置上 P1-N2 and N2-P2成分的振幅明顯增大，而控制組在休息時這些成份則會降低。因此，我們推測禪坐對於主要視覺皮質層及相關區域會有特定作用。

This dissertation reports the effects of Zen meditation on cardiovascular system and CNS electrophysiological behaviors. In the aspect of cardiovascular study, we evaluated the effects of meditation on cardiovascular system based on four parameters derived from blood pressure wave (BPW) that included the rising slope, normalized height of T wave, normalized height of V3 valley, and normalized height of D wave. The results showed that Zen meditation could lead to better heart ejection ability and aorta compliance, better arterial elasticity and aortic valve function, as well as the decreasing peripheral resistance of blood vessels. The observation allows us to infer that Zen meditation effectively improves functional characteristics of the cardiovascular system. To investigate the common experience of meditation practitioners - perception of inner light during meditation, we designed the flash visual evoked potentials (F-VEPs) experiments. Flash stimuli were applied before, during and after meditation- / relaxation-session in experimental / control subjects. Our results show that amplitudes of late latency components N3-P3 and P3-N4 at Oz decrease during meditation in the experimental group, whereas they increase in the control group. Both Cz and Fz amplitudes increase during meditation, yet decrease during relaxation for the control group. The latencies of some components increase under relaxation in control group, yet little variation (except P2) is observed in the meditators. According to our findings, Zen meditation induces particular effects on the visual nervous system and cortex that are distinguishable from those observed for normal relaxation. In chapter 4, we report our preliminary results of investigating the spatial focalization of Zen-meditation EEG (electroencephalograph) in alpha band (8-13 Hz). For comparison, the study involved two groups of subjects, practitioners (experimental group) and non-practitioners (control group). Wavelet analysis was applied to multi-channel EEG signals to extract the alpha rhythm. Normalized alpha-power vectors were classified by Fuzzy C-means based algorithm to explore various brain spatial characteristics. Number of clusters was determined by correlation coefficients of the membership-value vectors of each cluster center. Our results show that, in the experimental group, the incidence of frontal alpha activity varies in accordance with the meditation stage. And the results demonstrated three different spatiotemporal modules consisting with three distinctive meditation stages normally recognized by meditation practitioners. The parietal alpha activity in two groups decreased in different ways. Particularly, monotonic decline was observed in the control group. The phenomenon might imply various mechanisms employed by meditation and relaxation in modulating parietal alpha. In the research of visual perception under meditation based on alpha-dependent F-VEPs, we designed a strategy to record the F-VEPs under the consistent condition of background EEG – the emergence of dominant frontal alpha activity. According our preliminary results, the frontal alpha rhythms were more active during meditation. This event was thus used as the reference of meditation stage to trigger the flash stimuli. Based on the experimental protocol proposed, considerable differences between experimental and control groups were observed. In sum, amplitudes of P1-N2 and N2-P2 on Cz and Fz increased significantly during meditation, contrary to the F-VEPs of control group at rest. We thus suggest that Zen meditation results in acute response on primary visual cortex and the associated parts.