Extinction learning here does not mean extinction of the memories, but a new trial to learn that there is no connection between conditioned stimulus (CS) and unconditioned stimulus (US). The CS is the sound of a bell in the Pavlov’s dog and the US is a food. No reaction of salivation happens after no connection is learned between the bell sound and the food. Extinction learning, therefore, is not extinction or oblivion, but relearning over the previous learning through a new learning. What made extinct are not memories but conditionings in those memories.

To consider the mechanism of how mind contaminations are purified in Vipassana meditation, let us see specifically what mind purification means and what is purified. Mind contaminations here are considered such negative emotions as anger, hatred, animosity, anxieties, disgust or whatever. Their purification does not mean extinction of memories which cause those emotions, but developing the attitude of equanimity without emotional reaction to such emotions when they are evoked.

An underlying cause of those negative emotions is probably a sense of fear which would evoke such emotions as anger, hatred and so on. They must be unconscious reactions for self-protections. Behind this background implies ultimately a fear of death. So mind contaminations to be purified mean a sense of fear and mind purification means overcoming such a fear.

Memories registered and held in a brain are destabilized by being retrieved (recalled). This destabilization is necessary so that old memories should be renewed by new experiences. The memories consolidated can’t be updated. This destabilization is also necessary for stronger reconsolidation of the memories in the brain. Memories updated and consolidated are subsequently reconsolidated there. This process of memory retrieval and reconsolidation is ceaselessly conducted daily in the brain.

This destabilization and reconsolidation in the memory retrieval are used for the medical therapy of PTSD (posttraumatic stress disorder) and phobias. An ill subject is first forced to experience the trauma again in a secure environment. At that time when he or she faces the traumatic experience, a lot of neurotransmitters are released in synaptic clefts of the neurons of the ill subject.

This traumatic experience triggers a sense of fear which is induced by the released massive amount of neurotransmitters. When a massive amount of neurotransmitter（e.g. noradrenalin）is released in synaptic clefts, which causes the subject to feel a sense of fear, medication or propranolol（adrenergic blocker) is administered to block the neurotransmitter（e.g. noradrenalin） which is accordingly interrupted in the network of neurons, and a sense of fear disappears as a result. The ill subject does not forget the traumatic experience, but does not react emotionally against such a traumatic experience. In consequence he or she does not feel a sense of fear even at the time when the said experience is reproduced. This treatment does not work unless the sufficient amount of neurotransmitters is released in the network of neurons, or in synaptic clefts.

In Vipassana meditation body sensations are supposed to be observed. When the sensations appear on the surface of the body, a lot of neurotransmitters are considered to be released in synaptic clefts of the neurons. The awareness in observation of those sensations works subsequently to interrupt the massive amount of those neurotransmitters in synaptic clefts as medication (propranolol) does. The same circumstances as above mentioned in the phobia therapy are produced also here in Vipassana meditation.

To know why awareness of the body sensations blocks the neurotransmitters in the network of the neurons in the brain, let us see what awareness is. Awareness induces us not to react to such emotions as anger, hatred, anxieties and so on. When we suffer from violent emotions, we can hardly get emotionally involved in the situation if we are aware of the situation. Awareness brings a sense of calmness to control the mental situation, because in awareness the neurotransmitters which elicit those wild emotions are supposed to be blocked in the neuron network of the brain. Possibly some brain chemicals might be actually secreted and work as propranolol（adrenergic blocker) does in awareness.

If such is the case as mentioned above, in Vippasana meditation not only the quality of sensations, indicating a massive amount of released neurotransmitters in synaptic clefts, is important, but the quality of observation, blocking those neurotransmitters, is also important. The observation should not be simply feeling sensations, but should be so in awareness. The observation in awareness means, in other words, observing objectively. The observation in awareness would not bring about any effect in meditation without a good quality of sensations, but simply feeling sensations without awareness in equanimity would subsequently result only in the involvement of sensations. In this case Vipassana meditation lapses only into the reaction game of sensations of pain-and-pleasure, in which pleasant sensations are welcomed while unpleasant ones are not, as we do so in our daily life. Then, what is the significance of practicing meditation?

In Anapana before Vipassana, not only the power of concentration for deeper meditation is developed, but also awareness is built. Being aware of breathings develops the art of awareness. If sensitive meditators start to practice Vipassana meditation without developing awareness sufficiently, they are liable to feel sick and may suffer from unidentified complaints, such as a sense of nausea, because a massive amount of neurotransmitters, which cause various symptoms, can’t be blocked. A person impairing his or her health could be in danger, involved in unusual sensations, caused by an excessive amount of neurotransmitters. This phenomenon must be true, to some degree, of healthy persons.

Satipatthana Sutta says that cravings appear and disappear in the same place. Cravings sometimes lead to dukkha and at other times to pleasures. Arising and dissolution of those cravings are supposed to happen all in the same places as the synaptic clefts. When a massive amount of neurotransmitters are released there in the synaptic clefts, cravings appear, whose situation would be dukkha in some cases and would be pleasures in other cases, but if they are observed in awareness, they would be dissolved there in the same places as the synaptic clefts.

The craving is only the phenomenon in which a lot of neurotransmitters are released in the synaptic clefts. This phenomenon in the synaptic clefts, which is caused by the influence of the outer stimuli, results in the reaction of either pleasures or dukkha. Both pleasures and dukkha, however, are in themselves the same and inevitably disappear in due course. Everybody takes it for granted that he or she is reacting to the outside environment, but actually he or she reacts to himself or herself. The same stimulus from the outside should make the same reaction if he or she reacts to the outer environment, but in fact the reaction varies from person to person, because he or she reacts to the influence produced by the change in synaptic clefts instead of to the stimulus of the outside environment. And how he or she reacts depends on how he or she has been conditioned.

If we react to ourselves, instead of to the outside environment, we can't change anything in our life, unless we change ourselves. Even if we change the living environments, such as working and living places, to have a new life, nothing changes. Even if we go on a journey for a change, we should inevitably come back to ourselves someday. No journey can help us to change ourselves even if we travel to every corner of the world, though such a journey may be helpful temporarily.

And then, what should we do to change ourselves? We should observe sensations with awareness in equanimity, because it is sensations that cause those reactions. Identification of root causes is the first step to solve the problems. It is not society but sensations that cause us to feel unhappy. And it is also those sensations that cause us to feel angry instead of an enemy before us. There would be no phenomenon such as unhappy or angry if we don't react to those sensations, no matter what may happen before us.

The root cause of dukkha is the craving. The craving is the denial of reality, resulting from a sense of scarcity, the phenomenon in which we look for another reality because we can't be satisfied with the present reality as it is. There should be, consequently, conflicts between the present reality and another reality we look for. Conflicts cause dukkha, so cravings cause dukkha. Cravings are expressed as hope, ambition, or dreams for the future but they are also the denial of reality in terms of looking for another reality instead of accepting the present reality as it is. By expressing dukkha as such words as hope, ambition, or dreams for the future, we hardly feel dukkha as dukkha, because we can expect the cravings will be fulfilled in the near future, thanks to such rhetorical expressions. If we meditate for enlightenment, it must be the craving, because the reality that we are not enlightened is denied. Every life for success is a life of cravings, because the life that is not successful is denied.

We believe that we are born to live a successful life, accomplishing something worthwhile and a life of such is considered a better one. For that purpose the motivation is indispensable. But this motivation is also a craving in itself. The encouragement for success is to encourage people to have more motivations or cravings. Dukkha is limitless for a person who wants to do something better than what he or she has attained but who can't find what to do. This limitless dukkha must be caused by a motivation whose essence is a craving itself, and a craving inevitably causes dukkha.

Dukkha is the distance between the actual reality and the desired reality. So the bigger the craving becomes, the more painful the dukkha is, because the distance between those realities becomes wider and wider, if the craving is bigger and bigger. The stronger motivations or cravings for a better life may bring us a better life, but also bring us a limitless dukkha. As long as we live for a better life, we need cravings, and as long as we need cravings, we can't get away from dukkha. So our life is dukkha, as the truth of dukkha tells us.

If the craving is the root cause of dukkha, dukkha would disappear when we dissolve the cravings. But it is not so easy to eliminate the cravings, because we need cravings for a better life. Then, why do we look for a better life? It must be because there is a pleasing sensation in it. Any ordeal becomes a pleasing sensation when a better life is being sought for. The harder the goal is to achieve, the bigger the pleasing sensation becomes. That is the reason why people passionately head for a higher and more difficult mountain to climb, anoxic, solo, and in winter. Only a sense of pleasing sensation is visible and pain is invisible for a person trying to overcome such a bigger and greater challenge. Even if it is actually pain, it becomes a pleasing sensation for that person who is in the middle of challenging.

We expect only pleasing sensations in leisure and events which are held mainly for that purpose. As civilizations are being developed to eliminate pain and increase comfort, it is quite natural for anyone to live in such a way as looking only for comfort and avoiding pain in his or her daily life. But it is selfish to accept only pleasing sensations and refuse any pain, because pain or dukkha and comfort or pleasures are in themselves the same, only the phenomenon influenced by neurotransmitters in the brain as above mentioned. More pleasures mean as a result more dukkha. While dukkha possesses us, we have a craving to get rid of that, and while pleasures possess us, we have another craving to have more of those. Cravings can never be fulfilled, but result in dukkha as dissatisfaction. We have to pay for fulfilled cravings with tears, which must be our life. Dukkha originating from pleasures is much more agonizing than dukkha from the beginning. Although pleasures turning out to pleasures from pain or dukkha is much more pleasing, those pleasures are also dukkha in another viewpoint, which is, however, usually unnoticeable.

Civilizations bring pleasures, which however bring also dukkha to us at the same time. No matter how highly developed the civilizations are, they can't liberate us from dukkha, because bringing pleasures means at the same time bringing dukkha. The mentally unbalanced aspects in modern society might be caused by unnecessarily excessive pleasures resulting from the highly developed civilizations.

Because we don't know how to live a true life, we look only for pleasures, which must be the reason why our life is dukkha. We try to fulfill cravings to gain pleasures, but what is important is not to fulfill cravings, but to be aware of them. Being aware of those cravings would lead to the dissolution of those cravings as above mentioned. And then dukkha, produced by those cravings, would disappear. So would pleasures, however….

In Vippasana meditation, the quality of sensations is important, but the quality of observation is also important, as above mentioned. What we should bear in mind in observation is not to mistake feeling sensations for being aware of those. Being aware of sensations is observing them objectively, while feeling sensations means observing them subjectively. There are two phenomena in observation, that is, with awareness and without awareness. These two are totally different from each other, and precisely opposite. Observing sensations with awareness interrupts the flow of neurotransmitters in the synaptic clefts, resulting in blocking neurotransmitters in the neuron network, while observing sensations without awareness, or feeling sensations, speeds up the flow of them in the synaptic clefts. Various confusions may occur because the same word of observation indicates both of these two opposite phenomena. This confusion must not be ignored. As long as "you" observe "your" sensations, "you" can't be liberated from "you".

Observing sensations without awareness leads to the reaction game of sensations of pain-and-pleasure, in which meditators tend to become elated with pleasant ones and depressed with unpleasant ones. This results in the increase of mind contaminations in excitement, which is the opposite effect of mind purification that Vipassana meditation aims at. Being satisfied with such a game is, in a sense, dangerous, like drug or alcohol addiction in which pleasant sensations are sought for. What is important, is, pleasant sensations or unpleasant sensations, not only to observe sensations, but also to observe them in awareness.

The words, pleasant sensations or unpleasant sensations, are used here, but exactly speaking these are not sensations but perceptions, instead. Sensations, unknown, are changing all the time, and totally new. We can’t tell pleasant or unpleasant about what is totally new, because the unknown is beyond description.

Perceptions are reactions to the memories. Such reactions are made based upon the similar memories of the kind, and reactions to ourselves, which must be our daily habits. As long as we take sensations for perceptions, we can’t experience anicca, I am afraid. The way from sannya to pannya might be taking sensations for sensations instead of perceptions, which must be, in short, to observe sensations in awareness.

In Vipassana meditation, to observe sensations in awareness is probably to relive our life and correct it by way of sensations. Memories are retrieved as sensations and those destabilized memories for the update are relieved of conditionings through the process of awareness. Boldly speaking, in Vipassana meditation not only we live our life again and redress it, but also we live the whole memory from the origins of life to human beings again and redress it. Here in this process there is extinction learning in Pavlov’s dog, which neutralizes the conditionings between the bell sound and the food. As Pavlov’s dog has no reaction of salivation in response to the bell sound after extinction learning, people have no reaction of fear after Vipassana meditation. A sense of fear is overcome and the mind contaminations are purified.