Meditation: a neuronal exercise
As muscles grow and strengthen with physical activity, brain tissues do likewise with mental exercising. Muscle cells are worked out by tightening and loosening; neurons, by excitation and silencing.
Mental gymnastics is the acquisition and application of new knowledge and the development and practice of new skills (both physical and intellectual). When first acquired, any new set of abilities—fresh knowledge, arithmetic multiplication or ball juggling—becomes neuronal code; every time the recent acquired talent is put into action, the corresponding brain programs using the same neurons are run again and modified a little bit, strengthening the associated connections in the repetition. The reactivation of the neurons that participate in any experience the first time is the basis of informational and motor skills memory. If the original circuits are rarely used, they become progressively weaker and harder to recall; if used frequently, they imprint as permanent code that can be easily reused at any time.
Neuroplasticity is the human brain’s ability to expand and continually modify its very structure. Studies of this newly discovered power have shown that the continued development of physical and mental skills not only improves the utilization of existing neurons and help recover those already deteriorated, but also involves the generation of new neurons. In every case—reuse, recovery, regeneration—there is always more connectivity, more paths available to do more tasks; in other words, there is more brain—more thinking and acting gray matter—within the same head.
Interneuron communication takes place via electrical signals transmitted, modulated and amplified through neurotransmitters, a certain kind of chemicals produced and stored in each neuron. Through such signals the originating neuron instructs the receiving neuron to repeat the messages to its neighboring cells, with the commanding order to continue a cascading chain, repeating the received instructions to third neurons and asking them to continue the propagating sequence until reaching another brain region or the body organ where the required work is to be executed. Still, not all impulses are propagating signals. There is another kind of impulses which demand the neighboring neuron to reduce activity and slow down; when the order is radical, the receiving neuron is to remain quiet, do nothing and interrupt the messaging chain.
The neurons that generate the first kind of messages—orders to act—are called excitatory; those which send messages of the second type—orders to interrupt—are referred as inhibitory. Each neuron specializes from birth in one or the other feature. When inhibitory neurons are busy stopping signals, their work goes unnoticed and the owner of the nervous system is not even aware of the tireless blocking activity; inaction commonly goes unnoticed. The vast majority of neurons are excitatory but inhibitory neurons shoot much more often; it is estimated that throughout the nervous system the totals of excitatory and inhibitory signals are roughly the same. (It is worth noting that muscular movements are a complex alternation of instructions of both types of neurons working in the most extraordinary synchronization).
Like mental gymnastics, the different techniques of meditation are also neuronal exercises but of a very different type. For this article, we will exclusively refer to two types of meditation; more specifically, we will talk about two variations of Buddhist meditation. The first one, the vigilant observation of all bodily sensations, is an application of right attention (or right mindfulness), the seventh practice of the so called Buddhist noble path. The meditation of attention that we are interested in this article, which is commonly referred as mindfulness, is the voluntary and dedicated contemplation of the body and the sensations that occur therein.
The second form of meditation is the meditation of ecstasy (or ecstatic meditation, most commonly but inappropriately referred to as concentration), since it is essentially the application of the eighth noble practice, right ecstasy (or right concentration). The ecstatic meditation is a sequence of four progressive levels of introspection (or absorption) experienced by a skilled meditator when she isolates from sensuality and harmful mental states. During mindfulness, the person enters his/her «mental forest» with a map—with a predefined plan—and observes whatever she wants to observe following a set of instructions; the meditator looks for the experience. In the meditation of ecstasy, the meditator, after quieting body and mind, enters her «mental forest» and observes whatever comes up; the meditator surrenders to the experience. There exist instructions for mindfulness practice and the guide of a teacher might prove quite useful for beginners. In fact, The Manners to Establish Attention (also known as The Foundations of Mindfulness), one of the most important discourses of the Buddha, contains a detailed (though at times puzzling) list of the techniques that a student may follow to practice right attention. There are no specific directions for the meditation of ecstasy and the meditator is very much unguided and without any template; verbal instructions are of no use or help. (It is because of the lack of any specific devise to fix attention while meditating that the word “ecstasy” seems more appropriate than “concentration”.)
The neuronal training of physical exercises (as gymnastics or dance) and that of mental exercises (as chess or crosswords) primarily train and prompt to action systems of excitatory neurons. The neural training of Buddhist meditation focuses mainly on inhibitory neurons, the job of which is about stopping actions—repressing, calming, silencing.
Most types of meditation have four elements in common: (1) a quiet location (ideally isolated, which is particularly helpful for beginners); (2) a comfortable posture (most commonly a sitting posture); (3) an open attitude (which lets distractions and digressions come and go naturally without judging them); and (4) a focus of attention or mental device (an object, sensation or artifice on which awareness is centered and to which attention is brought back every time the meditator realizes his/her mind is wandering.)
While the first three elements of meditation are self explanatory, the fourth one calls for some clarification. Meditation objects may be body areas such as the space between nose and lips or the top of the head; sensations may be corporeal perceptions or breathing movements; mental devices, a more general word suggested by Dr. Herbert Benson of Harvard University, include, besides objects and sensations, things as colors, geometric figures, mantras, or sounds.
To move onto the physiology of meditation, we can now relate these four elements to the two classes of neurons. The passivity of the first three components turns off the millions of excitatory neurons that manage daily routines. A sharp decrease of neural activity occurs as soon as the meditator stays still, silent, isolated, and comfortably seated. Once motionless, quiet, lips together and eyes closed, the meditator automatically deactivates, for as long as the practice lasts, all the “motion driving, chattering, greedy and visual” neurons. For example, just by shutting eyes off we quiet about one fifth of our brain neurons; the function of vision is one of the most voracious consumer of gray matter. In less proportion, silence and stillness also entail significant reductions of excitatory neuron activity. Mouth sealing not only seek quietness but also strive for fasting; refraining from eating is the rule both while meditating—plain common sense—and during the two hours preceding the practice; by doing so digestive processes and the associated neurons remain in due rest.
The foregoing requirements are quite reasonable. What do we do when we want to rest or sleep? We, very naturally, adopt similar measures—quietness, silence, comfort. As science sees things today, the benefits of sleep are primarily in the territory of mind and the main beneficiary of snoozing is the organ that most needs it, which is obviously the brain.
Thus far sleeping and meditating are rather similar activities; in both excitatory neurons are put to rest following orders from their inhibitory neighbors. But it is in the directed work of inhibitory neurons—in actions under the meditator’s control—where the exclusive domain of the meditation game resides. The fourth element of meditation—attention focusing—does most of its work on inhibitory neurons; they are the differentiators of Buddhist meditation when compared with any other type of exercises. Mental devices are also what distinguish Buddhist meditation from sleep (where the attention goes off) and give Buddhist meditation (where awareness is total) the mental and vital advantages that the mere act of sleeping does not provide. Our nervous system, by necessity or convenience, permanently silences myriads of sensations in everyday life. With the continued practice of meditation it is possible to turn on and off those sensations; such routine is nothing else than the exercise—the training, the gymnastics—of inhibitory neurons.
Inhibition and mindfulness
During the practice of mindfulness the meditator observes—calmly, detachedly, impassively—every kind of sensations he/she perceives. In her detailed inspection of the body the meditator examines, part by part, the entire physical form and becomes aware, impartially and without any expectation, of a wide variety of feelings and vibrations that, under normal circumstances, the meditator does not perceive and, therefore, go completely unnoticed.
Throughout our nervous system (our brain is a subset of the overall nervous system) a fantastic number of neuronal data exchanges occurs every second. Physiological processes are permanently coordinated by millions of neuronal messages, the large majority of which are designed to operate quietly and noiseless. Still innumerable signals do clatter and must be silenced by the nervous system; they are sensible—they can be felt—but they are ignored or bypassed and go unobserved. If this did not happen, we would become insane amid the most confusing and roaring racket. Protecting our sanity is precisely one of the charges of inhibitory neurons; they exercise their deactivating role with cautious judgment, and let us detect and process consciously just the fraction of nerve impulses that interests us at every particular moment. During mindfulness, inhibitory cells partially and temporarily suspend their work—they take breaks—and, when that happens, we may perceive a variety of signals, as we move our mental monitoring throughout the different parts of our body. The role of inhibitory neurons is similar to that of the doormen who control the entrance to a show; it is in the interruption of their duty when their role becomes relevant. Silenced sensations are perceived when their corresponding inhibitory neurons stop working; people who do not have entrance tickets sneak into shows when doormen leave their post unguarded.
The reader may form a rough idea of the operation of inhibitory processes by simply maintaining attention for a few seconds in the contact points of the skin with her clothes or of his/her body with the chair where he/she is sitting. Sensations that otherwise would go unnoticed come up to awareness. With practice and time, the meditator will detect even the subtler signals that come from the flow of neuronal messages (which do not result from physical contact).
In the rotation of attention all over the different parts of the body and in the perception of otherwise ignored sensations, the meditator exercises inhibitory neurons, letting them turn on and off successively during the practice. This technique to activate and to deactivate neuronal circuits in the nervous system during the mindfulness practice is equivalent to tensing and loosening tendons and fibers in muscular subsystems during physical exercise.
Inhibition and meditation of ecstasy
In the meditation of ecstasy, the meditator sits isolated, both physically and mentally, from the outside world and gradually sinks in more and more profound levels of inner absorption. Through her passive attitude, the meditator allows that neuronal signals, whatever their nature is, vanish. Now the meditation mental devices are the inner silence, the serenity and the equanimity that she is experiencing; they are kind of “a posteriori” mental devices (as opposed to the “a priori” mindfulness devices on which you focus attention from the very beginning of the practice). In the process, the person enters levels of introspection increasingly insightful; million excitatory neurons go off (additional to those that were already silenced because the first three elements of Benson) and millions more inhibitory neurons, which were off, leave their rest and begin to exert their blocking function. As a result of these actions, the brain receives less and less signals and it ignores more and more things.
Radiologist Andrew Newberg and psychiatrist Eugene D'Aquili pioneered the research on the brain neural activity during meditation. Their experiments were carried on meditating Tibetan Buddhist monks as they reach their deepest levels of ecstasy, using computerized imaging technology; such work took place in the University of Pennsylvania Medical Center in the late nineties. Why Buddhist monks? Because the researchers wanted to work with very experienced groups; Buddhist monks are, so to speak, the "heavyweights" of meditation. The selected monks had some ten thousand hours of meditation experience; as control subjects, similar tests were conducted in parallel with recently trained meditation students.
Connected to sophisticated scanners and computer imaging units, the monks carried out their practice in complete isolation and, by tugging a thread, they indicated the investigators, who were next door, the instant at which they reached a peak meditative state. At that point Dr. Newberg entered the room and injected monks a radioactive liquid which traveled through the bloodstream into the monks’ brain and provided precise data on the neuronal activity at every brain point. These three dimensional data —location, intensity, time— were then displayed on colorful sequential charts.
As the meditation progressed, the images so obtained showed increased blood flow to the prefrontal cortex, an area identified as the seat of attention, indicating a boost in the neuronal activity there. At the same time, the images also suggested that in the upper rear sector of the brain, an area recognized as responsible for orientation, very little or nothing was happening. In this particular area human brains process the sense of space and time and manage information associated with the limits of their bodies; right there reside the data that we need to distinguish the end of our physical frame and the beginning of the rest of the world.
What explanations are suggested for such contrasts of neuronal activity in the monks’ brains? If the orientation area of a person’s brain does not receive any input signal, which is the expected result of deep ecstasy, it is as if the subject did not have any clock, meter, compass or radar—for all intents and purposes, a complete absence of any orientation instrument. When this happens, Dr. Newberg explains, "the brain has no choice but to perceive the self to be endless, interwoven with everyone and everything.” I do not enter the theological or psychological considerations of these findings, but they do provide some sense to the descriptions of mystical raptures—dissolution of identity, disappearance of the notion of time, unity with universe, wholeness—as described by those claiming to have undergone such states.
On the other hand, why is there so much neuronal activity in the prefrontal cortex, the seat of attention? Should not the seat of attention display stillness and silence as does the area of orientation? The meditation of ecstasy is a passive observation, without any judgment, comparison or analysis; there are no calculations, recalls or creative actions involved; there is no rotation of attention around some mental devices. Mind awareness is simply placed—quietly, impartially—in the outcome of surrendering to the experience. Should not neuronal activity show negligible in the prefrontal cortex? Is this not what you would expect?
The paradox has, in fact, a reasonable explanation. My interpretation is that, when the Buddhist monks reach their deepest levels of ecstasy, their neurons in the seat of attention are "actively" dedicated to send inhibitory signals, they are actually quite busy restraining any impressions that may distract the meditator from the insightful experience. In other words, there is in fact a lot of work going on there but it is of an inhibitory nature. The interaction of the sense organs and their corresponding objects—vision and vision objects, audition and sounds, feel and contact, and so on—is being blocked by inhibitory neurons, thus computerized images display an intense activity. In particular, inhibitory neurons block away the flow of signals towards the region associated with orientation; consequently nothing seems to happen in this area, therefore, the images show "a complete silence," thanks to the dutiful labor of inhibitory processes in the seat of attention.
Benefits of Buddhist meditation
Scientific and popular literature documents in abundance and detail the well-proven benefits of meditation—any kind of meditation within Herbert Benson’s parameters—in the reduction of the negative effects of stress in modern life. The discussion of this subject therefore becomes unnecessary and redundant. Instead we prefer to focus our interest in the specific benefits of practicing the Buddhist meditations of attention and ecstasy.
Let us begin the subject by associating the physiology of the nervous system with the Buddhist perspective. Every action being performed by us or onto us (moving, thinking, listening, being touched, breathing, etc.) involves the generation of signals—the transfer of chemicals and electrical charges—between neurons throughout the whole nervous system; the effecting of these minute transactions always entails very subtle sensations within our whole body, the organ of the touch sense. The vast majority of these sensations are silenced by inhibitory neurons or mitigated by the reduction of activity of excitatory neurons. This is on the physiology side.
On the Buddhist side, we need to briefly discuss what is called the five components or aggregates of individuality, namely the physical body or form, sensations, perceptions, conditioned reactions, and cognition or memory. These aggregates are the generators—the structure, the makeup—of our sense of identity (the self or ego). The acknowledgement of this sense of identity as an illusory convenience is at the heart of the Buddhist doctrine.
Now science and Buddhism together: Sensations, the second aggregate, is a permanent phenomenon, sensations are always going on; their perception, on the other hand, is optional at brain’s discretion. Sense objects proliferate and permanently send sensorial signs but the brain decides which ones it is to perceive. The large majority of sensations are restrained for the very convenience of the individual. It is here where the conditioned reactions, the fourth aggregate, play a very critical role. Let us clarify this important subject. Conditioned reactions are neuronal instructions of automatic execution in the three-step chain of (1) enjoyable or hurting sensation – (2) pleasant or painful perception – (3) repeatable or avoidable action, Conditioned reactions are recorded and saved in the brain where cognition, the fifth aggregate resides. When every sensory signal is processed, its perception is checked against the “cognition data bank” and the associated conditioned reaction is triggered. Conditioned reactions are the evolution mechanism for learning and survival but they are also the origin of unwanted attachments and rejections (the negative attachments, the anti- attachments, so to speak).When such attachments and rejections grow out of control, they become recurring addictions and permanent aversions respectively.
The core purpose of Buddhist meditation is the purification—the decontamination, the cleansing—of the meditator’s mind. Buddhist meditation is a workout of the nervous system inhibitory mechanisms. Observing attentively the successive activation and deactivation of neuronal circuits make meditators aware of the mind movements associated with their addictions (obsessions) and aversions (phobias). The most promising benefits of Buddhist meditation is the development of a permanent awareness which goes beyond the secluded practice.
The Buddha knows that people do not become addicted to alcoholic beverages (many people do drinks without developing addiction); we become addicted to the sensations they trigger on each of us. Habits grow out of the desire to experience again pleasurable actions; the neuronal code to repeat such actions becomes automatic and uncontrollable conditioned reactions. The Buddha recommends the abstention from toxic substances to those who want to maintain a decontaminated mind; this is an elementary preventive measure. For those who already are victims of addiction and need, by all means, purifying actions, meditation is the corrective step. (Needless to say, meditation is a practice recommended for any individual, under any circumstances, not only for those who are already addicted.) This is by itself a worthwhile benefit of Buddhist meditation. But it is in the prevention and treatment of problems more complicated than routine addictions and attachments, with which most everybody is acquainted, where Buddhist meditation is recently showing even more significant results.
Many psychological and psychiatric problems seem to be rooted in disarrays of inhibitory mechanisms. We have to remember that roughly fifty percent of all neuronal orders are inhibitory. If a fraction of the millions of inhibitory signals that are sent every second is not properly initiated or completed, myriads of otherwise quiet neurons are to remain abnormally active giving way to unexpected and uncontrolled behaviors. Inhibitory neurons are an important factor in the conservation of order and harmony by retaining unnecessary signals, silencing superfluous noise and keeping balance of nervous processes.
Over the last decade there has been an increasing interest in the application of Buddhist meditation (or of adapted versions of Buddhist meditation techniques) to deal with a number of behavioral disorders. Malfunctioning of inhibitory neuronal mechanisms has been associated with a variety of problems both neurological (as attention deficit and child hyperactivity) and psychological (as phobias and obsessive compulsive disorders.)
Corrective modifications of behavior (in fact, all behavioral changes) are always the result of alterations of brain chemistry. Such alterations might be rather benign as in conversational therapies and addicts’ anonymous meetings or pretty chaotic as in religious experiences or electroconvulsive therapy. A new balance among brain neurotransmitters is restored after the experience which hopefully should exclude forever the specifically targeted problems (though a disposition to go back to the old order—to the old disorder is probably more appropriate—may remain). Buddhist meditation is the softest therapy; what it does is reducing brain activity at a minimum level, maintaining that level for a while and letting normality go back by itself—no instructions, no interventions. The more frequent the practice and the longer every session, the higher the chances to return to a natural harmony.
The reasoning of evolutionary psychology to explain phobias and compulsive obsessions is straightforward. The avoidance of physical and emotional pain (hunger, injuries, loneliness) and the pursuit of pleasure (food, wellbeing, sex) played a crucial role in evolution. The fear of pain promoted the survival of individuals; the pursuit of pleasure assured the permanence of species.
In every situation—it happened trillions of trillion times—when fears and anxieties vanished (preys hunted, predators eradicated or evaded, sexual drives met) the associated triggers —hunger, fear, lust—were timely inhibited. Natural selection programmed these triggers in our genetic code; the best fitted survived. However, when the same mechanisms do not work properly in our modern daily transactions, compulsive behaviors (gluttony, drug addiction, sex obsession, etc.) or phobias (unfounded fears to inexistent dangers) come into sight.
Initial results of Buddhist meditation in the treatment of such disorders are highly promising; the exercise of inhibitory neurons, which are activated and silenced during the meditation practice, seems to be the cause of such positive results. The Buddha’s discourses never refer to compulsive behaviors or phobias; he figuratively spoke about thirst to cover both intense desires (cravings) and hatred (aversions). For him obsessions and phobias, without using such words, were just impurities from which human mind must be decontaminated and purified.