Meditation: Pleasure, Part II

In order to understand pleasure, we have to look at the logistics of how the mind and the body experiences pleasure. Pleasure is created by neurotransmitters. Neurotransmitters are chemical substances that are released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure. The exact number of neurotransmitters is unknown but more than 200 have been identified. Neurotransmitters are different types of protein substances that are manufactured by the body from the foods we eat. Most of the western diets are high in protein, so the body does not have much trouble in making neurotransmitters. The neurotransmitter that has been related to pleasure is dopamine. Dopamine  has a number of important functions in the brain; this includes regulation of motor behavior, pleasures related to motivation and also emotional arousal. It plays a critical role in the reward system.

Dopamine is made from the amino acid L-Dopa, which can be synthesized indirectly from the essential amino acid phenylalanine or directly from the non-essential amino acid tyrosine. These amino acids  are found in nearly every protein and so are readily available in food, with tyrosine being the most common. Although dopamine is also found in many types of food, it is incapable of crossing the blood-brain barrier that surrounds and protects the brain. It must therefore be synthesized inside the brain to perform its neuronal activity. That is not a problem because both L-dopa and tyrosine can cross the barrier and therefore Dopamine is made by the brain, for the brain. Dopamine can cause health problems if an individual has too little or too much in their system. The most common disease linked to a Dopamine deficiency is Parkinson’s Disease. You can measure Dopamine in the blood. Since Dopamine can not cross the blood brain barrier, this is not going to tell you how much Dopamine is in the brain. Until recently there was no way of knowing how much Dopamine was in the brain. Now MIT has developed MRI sensors, that consist of magnetic proteins that can bind to dopamine. When this binding takes place, researchers can continuously monitor dopamine levels in a specific part of the brain. One of the key discoveries was that dopamine did not make neurons more active, but made neurons active for longer periods of time. Unless your are going to be hooked up to the these sensors, no one is really going to know what is happening in the dopamine brain system.

There are other feel good substances in the body. Dopamine, Serotonin and Oxytocin often referred to as the happy hormones, even though only one is a hormone. They are all connected with each other when it comes to pleasure. Endorphins are stored and produced in the pituitary gland. They can inhibit pain mechanisms. You create endorphins when you do something related to exercise that you really like to do. All of these chemicals are involved in the feelings of pleasure and reward and how to get both. When any of these chemicals get out of whack not matter what the reason, we begin to have problems. This can make pleasure seem so confounding at times. Sometimes, it is what we do to bring all this in balance, that can at times make everything worse.

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