禅法与脑科学的关系考察

前言：对于心与脑的关系，若参考爱因斯坦有名的 “质量”与“能量”的互变物理方程式E ＝mc2（能量=质量 ×光速平方），似乎可将 “心”、“脑”的互变关系以 “心＝脑×众生 2”来表示微小的“脑”量可经由“众生”量的累积产生巨大的“心”力。

一、四念住与三重脑理论：

八十年代，我在日本留学期间，第一次读到美国神经生理学家马克林(Paul D. Maclean)所提倡的“三重脑理论”时，有一股很强烈的震撼直达脑海的底层，我的脑袋似乎也被震裂成三片的感觉。所谓“三重脑”是说：“人类的脑包含有最深部的“爬虫类型的脑”的脑干（生命中枢；掌管呼吸、心脏活动、体温调节等维持生命功能），与约两亿年前的爬虫类时代的演化有关。包围脑干的外侧是‘原始哺乳类型的脑’的大脑旧皮质（本能与情绪中枢，掌管食欲、性欲以及愤怒、恐惧等情感），与约一亿五千万年前原始哺乳类的演化有关。最后覆盖其上的就是演化到灵长类才发达的‘新哺乳类型的脑’的大脑新皮质（智慧中枢，掌管理论性思考、判断、说话等等高度智慧活动）”。人类的胎儿的脑部也是依此三重顺序发展；先后三种的演化期的脑，由内到外依序共存于人脑中。

当时，我似乎感受到我和鳄鱼等爬虫类、马等哺乳类等无比的亲密关系，再次憾动“我是万物之灵”的迷执，更小心、踏实的去面对人类隐藏在深层的本性；同时也体会到生命各物种间之相似相续、不常不断的演化过程，生命个体犹如生命之亘古长流中的水泡，缘起缘灭，不生不灭。

之后，在撰写博士论文时，探讨到《念住经》之“四念住”（又译为“四念处”）修习法。佛陀教导比丘们，学习认识自己的身体（呼吸与动作）、受（感觉与感受）、心（心识）、法（真理）等四方面，时时彻知无常，去除对身心世界的贪瞋，使“觉察性”（念，awareness, mindfulness）念念分明，忆持不忘，敏锐且稳定（住，setting-up，establishment）。我对于身、受、心、法等“四念住”的观察顺序，与上述脑演化的“三重脑理论”，发现似乎有不谋而合之处时，再次产生一股震撼力，影响到我在动静修行的感受与理解。

《念住经》不仅是南传（声闻乘）佛教的禅修指南，比丘们亦常在垂死人的病榻边读诵《念住经》，以净化临终者最后的心念。“四念住”其实是佛教修行的基本架构，在菩萨乘佛教中，也受到重视，例如：隋朝天台智者大师曾经讲说，他的学生章安灌顶笔记成《四念处》四卷 (T46, no. 1918)。

首先，与身体有关的“身念住”的修习阶段中，有最常用且最实用的修习法，叫做“忆念出入息法（数息观）”。《念住经》说明：修行者应觉知呼吸时气息的出入情况。入息长、入息短时，清楚了知：“我入息长、入息短”；出息长、出息短时，清楚了知：“我出息长、出息短”。他如此训练自己：“我当感受全身，而入息、出息”；他如此训练自己：“我当寂止身体的制约者（呼吸），而入息、出息”。

从“三重脑理论”来看，呼吸作用与人脑中担任掌管呼吸等维持生命功能的“爬虫类型的脑“的脑干有关，”身念住”之“出入息”的觉知让修行者能经常体会生命中最基本的拥有—呼吸，我们出生后第一个拥有，死前最后的拥有，它是我们最忠实的亲友，但是我们却很少与它对话。我们也常忽略这种最基本“活着的感受”，不去珍惜如此古老、约两亿年前的爬虫类时代所演化之呼吸的价值与意义。我们若能体会“一息尚存，永乐不忘”的心态，“呼吸”可以说是不用花费任何成本、几乎不需任何其它条件的“游乐对象”或“玩伴”，随时可以与“呼吸”玩的妙趣横生，乃至生命最后一口气。

其次，与约一亿五千万年前原始哺乳类的演化的大脑旧皮质（情欲与情绪中枢）有关的“受念住”修习阶段。《念住经》说明：修行者在经历或执着于快乐、痛苦、不苦不乐等不同的感受时，他清楚了知：“我正经历或执着于快乐、痛苦、不苦不乐的感受”。他观察感受当中不断生起、变化、消失的现象，练习区别“我的感受”（my feeling） 与“一种感受”（a feeling）的不同，知道感受如何制约心，以处理不当的情绪。相对于呼吸是身体的制约者（身行），所以能借着调节呼吸来调节身体，令其安适；同理，感受是心的制约者（心行），所以能借着调节感受去控制心，令心安止。

第三阶段是与数百万年以前演化之“新哺乳类型的脑”的大脑新皮质（智慧中枢）有关的“心念住”修习阶段。《念住经》说明：修行者当心有贪爱或无贪爱、有瞋恨或无瞋恨、有愚痴或无愚痴时，清楚了知心有贪爱或无贪爱、有瞋恨或无瞋恨、有愚痴或无愚痴。当心有收摄或无收摄、心广大或不广大、有上或无上、心专注或不专注、心解脱或未解脱时，清楚了知心有收摄或无收摄、心广大或不广大、有上或无上、心专注或不专注、心解脱或未解脱。他观察各种心态不断生起、变化、消失的现象，勇敢诚恳的去面对自己的心念，就像在镜中看自己的脸一样；练习区别“我的”与“一种”的不同，以处理不当的心态。然后，才能以此心智进入第四阶段“心念住”修习，了解至高无上之法（真理）－无常、苦、无我、空、涅盘。

二、脑科学之“变动之我”与佛教之“无我”观

随着脑神经科学的进步，对于什么是自我？它位于大脑何处？大脑如何制造一个统一的自我？大脑与心智的关系为何？等问题有了新的观点，在坊间也有以此为主题的科学普及书籍，例如：方伯格（Todd E. Feinberg）所著Altered Egos: How the Brain Creates the Self (Oxford university Press. 2001; 中译本：《我从变中来－大脑如何营造自我？》)。这些科学的成果与佛教之“我”与“无我”的教义，是否有可以产生互相对话与交流之处？或者是否有助于体会无我、无我所之观察？

在日常生活中，我们可以感觉到似乎有统一性、常恒不变性的“我”，即所谓“意识经验及生存重心的主体”。但是方伯格医生观察到一些因脑受损而改变了“自我界限(margins)”的病人，也即是改变了自我与本身、自我与他人及自我与世界的关系。

有位中风的病人的额顶叶因血管梗塞而受损，造成“身体失识症”（Asomatognosia；缺乏对自己身体的识别），她不知道自己的左臂是属于她的，而认为它是属于以前因中风过世的先生所有。有病人则一直不停地想要将他的左臂赶下床，有的向护士抱怨有人和他一起躺在病床上。例如：一位四十八岁的妇人被问到她的左边身体时，她回答：“那是一个老人，一直都躺在床上”；某军医院的一位军校学生则一直抱怨：“在他自己身体与墙壁之间，已经没有空间给‘那个人’了”；也有病人在提起自己瘫痪的左臂时抱怨说道：“别人是没有权利到她的床上”。因脑受损而拒绝、误认或否认他们一辈子所熟悉身体的一部分的症状，显示出自我边界的弹性令人惊讶。

此外，方伯格医生发现：自我并不是像皮肤那样将我们与世界清清楚楚地划分出来，它像变形虫，具有可以改变形状、界限、应需求而变形或再生某个部件的能力。例如：因头部受伤、中风而产生“误认症”病人，有些会认为有人冒名顶替他们的父母或夫妻。有些则将陌生人认为是某位他所认识的人，甚至认为医院里满是他的家人、朋友和同事。也有病人不是误认实际的身体，而是误认镜中的影像不是自己，而是长相类似的陌生人，甚至对镜子泼水、扔东西、大声斥责，试图将他们的替身赶出房子。此外，患有“他人之手症”的病人在无法控制的情况下，会用其中一只手掐住自己的喉咙。

从诸多“自我纷乱”病人的大脑中，我们可以发现：大脑的许多不同区块都对自我的建构及维护扮演不同的角色，但是现代神经学已证明脑中并没有一处是掌管自我的区块。方伯格医生则假设大脑是以制造意义(meaning)与目的(purpose)的包含性阶层(nested hierarchy)来建构自我的统一。并且，他也认为：自我边界的转变并不只限于脑部损伤的人。我们每一个人几乎每天都经历“自我界限”的改变，每当我们认同别人、设身处地替别人着想，对别人的痛苦感同身受，或为随喜别人的好运时，我们与他人心智便有部分合并，分享到他们主观的经验。当我们进入彼此认同的心智状态时，便进入心智的新包含性关系了。

佛法则认为：造成“我”(self)的观念，是一种模模糊糊的“我存在(I AM)”的感觉。这“我”的观念，并没有可以与之相应的实体，若能如此观察，则可体悟涅盘。但这不是容易的事。在《杂阿含经103》中，叙述差摩(Khema)比丘身得重病，诸比丘派遣某位瞻病比丘前往探病。差摩承认：虽然他能正观五蕴身心中，了知“无我”与“无我所”，但还不能离我欲、我使、我慢，不是一位断尽烦恼的阿罗汉。因为对于五蕴身心，仍有一种“我存在(I AM)”的感觉，但是并不能清楚的见到“这就是‘我存在’(This is I AM)”。就像是一朵花的香气，分不清是花瓣香、颜色香或花粉香，而是“整体”花的香。所以，已证初阶圣果的人，仍然保有“我存在”的感觉。但是后来继续精进修行时，这种“我存在”的感觉就完全消失了。就像一件新洗的衣服上的洗衣粉的药味，在衣柜里放了一段时间之后，才会消失。同样的，修行者增进思惟，观察生灭，此色、此色集、此色灭，此受、想、行、识，此识集、此识灭。于五受阴如是观生灭已，我慢、我欲、我使，一切悉除，是名真实正观。

Some relationship between Meditation and Ｒain Science

Huimin Bhiksu

Foreword

To illustrate the relationship between mind and brain, as an inspiration from A. Einstein’s Equation of E = mc2 (Energy = Mass x 光速2) that explains the conservation of mass and energy, it seems that we can put it as M = B x B2 (Mind = Brain x Beings2). In the equation, the slight amount of brain interacting with the accumulation of all beings can generate a tremendous energy of mind.

1. The Four Mindful Establishments vs. the Triune Brain Model:

During the 1980’s when I studied in Japan, I read for the first time about the Triune Brain Model proposed by Paul D. Maclean, I was so shocked as if my brain had split into three pieces as well. In this model, the triune brain consists of three portions: (1) The innermost Reptilian Brain, or the R-Complex, which including the brain stem and the cerebellum is the survival pivot controlling the autonomic functions such as breathing, heartbeat and the adjusting of body temperature. This portion of the brain is related to biological evolution in the Reptilian Age around 200 million years ago. (2) The Old Mammalian Brain, or the Limbic System, which surrounding the brain stem is the source of emotions and instincts such as appetite, sexual desire, anger, and fear. This portion of the brain is related to the mammals’ evolution around 150 million years ago. (3) The top layer of the brain referred to as the New Mammalian Brain , or the Neocortex, which had not extensively developed until it evolved in the brains of the primates, especially the humans. The neocortex of the brain plays a central role in highly intellectual functions such as thinking, judgment, and language etc. The embryo brain of a human being also develops in this threefold sequence, with the parts of the brain specifically evolved in three stages coexistent.

Thereupon, I seemed to realize how closely I am related to a reptile like a crocodile or to another mammal like a horse, and my rooted conception that ‘I am on top of all beings’ was being shaken once again. I knew I need to be even more careful and honest to face the underlying nature of human beings. I also realized the nature of similarity-and-continuity, and the non-permanace-and-non-nihility of all beings in the course of evolution: every individual arises and falls interdependently in a continuous way, like the foams in the river of life that flows everlastingly.

Later on, I was writing my doctoral dissertation discussing the subject of ‘Four Mindful Establishments’ (also known as ‘Four Mindful Dwellings’), the practicing method taught by the Buddha in sutra Establishment of Mindfulness, from which the monks learned to know their body (breathing and actions), sensation (feelings and receptions), mind (consciousness), and the Dharma (the Truth). The monks practiced in a way that they knew clearly in every moment that everything is impermanent, and that enabled them to eliminate their greed and hatred toward their physical and mental worlds and keep their awareness, or mindfulness, clear and continuous, keen and stable (setting-up). During that time, I was shocked again when I found the practice procedure of the Four Mindful Establishments seems to be identical with the evolution course proposed in the Triune Brain theory. The finding used to influence my feeling and understanding in daily practice.

In the Southern (Theraveda) Buddhist tradition, apart from being regarded as the guide for practicing meditation, the sutra Establishemt of Mindfulness is often read to a dying person at his bed to purify his last thoughts. As a matter of fact, the Four Establishments of Mindfulness is the basic course for Buddhist practioners, which has also been highly valued in the tradition of Bodhisattva's Vehicle. Venerable Zhiyi of Tiantai sect in Suei dynasty, for instance, once expounded this sutra to be noted down by his disciple Zhangan Guanding as Four Dwellings of Mindfulness in four fascicles (T46, no. 1918).

First of all, in the stage of the Establishment of Physical Mindfulness concerning bodily activities, the most practical and frequently used method is ‘mindfulness on breathing-in-and-out (breath counting meditation)’. The sutra Establishemt of Mindfulness states that a practioner should be aware of his own breath in and breath out. When the in breath is long or short, the practitioner should clearly know: ‘I take a long breath in and I take a short breath in;’ when the out breath is long or short, he should clearly know: ‘I exhale a long breath and I exhale a short breath.’ He trains himself such that: ‘I should feel my whole body while breathing in and out;’ he trains himself such that: ‘I should stop the conditioner of my body (the breathing) while the breath in and out.

In terms of Triune Brain Model, the breathing function is in relation to the brain stem referred to as the Reptilian Brain, which is in charge of such sustaining functions of life as breathing. The awareness of breathing-in-and-out as trained in the stage of the Establishemt of Physical Mindfulness let practitioners be constantly aware of their basic owning in life---breathing. Breath is our first friend on birth, and our last possession on dying. It is our most faithful friend, and yet to whom we seldom talk. Often do we also neglect the basic ‘feeling of aliveness’, overlooking the value and meaning of the breathing that had evolved in the ancient Reptilian Age some 200 million years ago. If we learn to appreciate the reaization that ‘with one remaining breath, happiness accompanies forever,’ then ‘breathing’ will be the free, and unconditional ‘playing object’ or ‘playmate’ who we can play with merrily anytime, even till the last breath of life.

Secondly, in correspondence with the Limbic System of the brain evolved in the mammals around 150 million years ago, which is the source of desire and emotion, the stage concerning Establishment of Sensuous Mindfulness as accounted in the sutra Establishemt of Mindfulness states that while experiencing or attaching to pleasant, unpleasant, or neutual feelings, the practitioner should clearly know: ‘I am experiencing and attaching to pleasant, unpleasant and neutual feelings.’ He observes the repeated arising, changing and falling of feelings to train himself in distinguishing ‘my feeling’ from ‘a feeling’. In knowing how the feelings condition the mind, he is able to deal with improper emotions. As breathing is the conditioner (physical activity) of the body, by adjusting which the practitioner adjusts his body as well, so are feelings the conditioner (mental activities) of the mind, by modulating which the practitioner controls and stablizes his mind.

The third stage is the Establishment of Mental Mindfulness, which is compared to the biological evolution occuring only a couple of million years ago, referred to as the New Mammalian Brain, or the Neocortex, functioning intellectual activities. In the sutra Establishment of Mindfulness it states that when there is or is no greed, is or is no hatred, is or is no delusion arising in the mind, the practitioner should clearly know there is or is no greed, is or is no hatred, is or is no delusion arising in the mind. When the mind is absorbed or not, vast or not, upward or not, concentrated or not, liberated or not, the practitioner should clearly know the mind is absorbed or not, vast or not, upward or not, concentrated or not, liberated or not. He observes different states of mind arise, changing and disappear, bravely and sincerely watching each mental activity of his own as if watching the reflection of his own face in the mirror. He learns to distinguish ‘mine’ from ‘one’ so as to deal with improper states of mind. Then, he is prepared to enter the fourth stage, the Establishment of Dharmic Mindfulness, to understand the supreme Dharma, namely the Truth of impermanence, suffering, selflessness, emptiness, and nirvana.

2. The Altered Egos in Neuroscience vs.

the Egolessness in Buddhism

Along with the development of neuroscience, such questions as to ‘What is the self?’ ‘Where is it located in the brain?’ ‘How does the brain produce a unified self?’ and ‘What is the relationship between the brain and the mind?’ have been given answers in new perspectives. The same subject has also been discussed in books categorized as popular science, such as Altered Egos: How the Brain Creates the Self (Oxford university Press. 2001; with the Chinese rendering《我从变中来－大脑如何营造自我？》). Is there the possibility of mutual talks or communication between these scientific achievements and the Buddhist teaching of ‘self’ and ‘selflessness’? Or will these achievements come to help the realization of ‘no self’ and ‘no possessions of the self’?

In the daily life, we seem to perceive the existence of a unified and permanent ‘self’, i.e. ‘the subject of conscious experience and living focus’. However, Dr. Feinberg found among his patients that those having undergone brain damage would have different boundaries of the self. In other words, the change in their brain had transformed the relationship between the self and itself, the self and other people, and the self and the world.

A patient’s parietal lobe was damaged due to a stroke, which caused an Asomatognosia (lack of recognition to one’s own body) to her. She was unaware of her left arm, but instead believed it belonged to her husband who died of a stroke. Another patient kept expelling his left arm off the bed, and still another complained to the nurse of someone lying beside him. There was a 48-year-old woman, for example, when asked about her left-side body, giving the answer: “That is an old man lying in the bed all the time.” Another example was that a military school student in a military hospital kept complaining there was no more room between his body and the wall for ‘that man’. One patient, referring to her paralyzed left arm, accused that other people had no rights to stay in her bed. The symptoms, caused by brain damage, of rejecting, mistaking or denying parts of the body that used to be so familiar to oneself for life shows that there is surprising flexibility in the boundaries of the self.

Furthermore, Dr. Feinberg found the self does not mark its boundaries with the world as the skin. It is rather like an amoeba, which can alter its shapes and boundaries to adapt to circumstances, and which reproduces parts of its body when necessary. For instance, among patients with Misidentification Syndrome caused by damage to the head or by apoplexy, some would consider other people had assumed the identities of their parents or spouses. Some would mistake a stranger for an acquaintance, or believe the hospital was full of their family, friends and colleagues. Others would deny their reflection in the mirror, although they accepted their physical body. They thought the image was certain stranger in their own resemblance and even poured water, threw objects, and scolded at the mirror in an attempt to drive him/her away. Whereas patients of Alien Hand Syndrome being out of control might pinch their own neck with their own hand.

In the study of the brains of patients with ‘disorders of the self’, neuroscientists found that different parts of the brain play different roles in the construction and maintenance of the self. However, according to modern neurology, there is no specific area in the brain that is in charge of the self. Dr. Feinberg’s hypothesis is that the brain uses nested hierarchy of meaning and purpose to build up a unified self. He also pointed out that changes of the boundaries of the self do not only occur to people with brain damage, but they are also experienced by everyone almost everyday. Whenever we agree to other people’s opinion, put ourselves in others’ position, sympathize others’ suffering or rejoice at others’ fortune, our mind is merged partially in that of others, sharing their subjective experiences. After we enter the mutually agreed state of mind, we will be in the newly built relationship of nested hierarchy.

In terms of Buddhism, the concept of ‘self’ is an obscure feeling of ‘I AM’, which has no corresponding substance. Meditating on this teaching of the Buddha is the way leading to the realization of Nirvana. But it is no easy work. In Saṃyuktâgama 103, it accounts that on one occasion, the monk Khema was seriously ill and the Order sent a representative monk to visit him. Monk Khema admitted that although he held a correct insight that within the Five Aggregates there are no ‘self’ and ‘possessions of the self’, he was still unable to be detached from self-desire, self-compulsion (self-affliction), and self-conceit, and that he was not an arhat with all the defilements destroyed. For he still possessed a feeling of ‘I AM’ with regard to the Five Aggregates, although he did not clearly see ‘This is I AM’. Just like the fragrance of a flower, you cannot tell whether it comes from the petals, the color or the pollen. It is the whole flower that emits the scent. Therefore, a practitioner who consummates the first of the Four Fruits (stages) still possesses the feeling of ‘I AM’. But if they continue to practice diligently, this feeling of ‘I AM’ will finally fades away. It is as a piece of newly washed clothing carrying the scent of the detergent, which needs to be put in the closet a period of time for the scent to fade away. Likewise, practitioners make progress in contemplation and observe phenomenal arising and decay to realize ‘this is form, this is the origin of form, this is the cessation of form,’ and ‘this is sensation, perception, volition, and consciousness,’ and ‘this is the origin of consciousness, this is the cessation of consciousness.’ After having contemplated on the becoming and decay of the Five Aggregates, all defilements such as self-conceit, self-desire and self-compulsion will be completely eliminated, and which is called the Right Contemplation as it truly is.