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Neuroscience & Karma
responses of the cortex. In man, the orbital zone of the frontal cortex is an especially important inhibitor of the tendencies produced by the lower regions.
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The actions of the lower parts of the brain are greatly influenced by the higher parts. Experience and learning are such dominant factors that in man the lower centers are largely controlled by cultural or individual influences. It is characteristic of humans that they can be educated. We may have innate capabilities for aggression and violence, but it does not follow that we need to use them.
5. The Chemistry of Aggression/Violence
Three Chemical transmitters, characteristic of some of these areas, have been identified and their amounts can be altered by several deliberate mental procedures. These are (1) noradrenaline (NA) and (2) dopamine (DA). Increase in the levels of a third amine (3) serotonin is found to depress aggressive behavior. A proper ratio between these amines is important in control of aggression.
The discovery that these substances are active in the brain has been made only recently, but for many years it has been known that adrenaline produced by the adrenal gland is involved in reactions of alarm and stress. In the brain, amines are 'transmitters' used by one nerve-fibre to activate another at synoptic junctions. It is very interesting that the central part of the adrenal gland (the medulla) is devoted to producing similar substances and sending them in the blood all round the body. The 'alarm reaction' that they cause was one of the first examples of emotional processes to be studied by physiologists. Stimulation of the nerves to the adrenal gland releases adrenaline, which has the effect of preparing the body for action. The heart speeds up, digestion stops, blood is diverted from the viscera to the muscles and sugar is mobilized as fuel from the liver. It is indeed strange that this and the similar substance, noradrenaline, are at the same time at work in the intricate networks of the core brain, making the animal or man alert, attentive, and ready to respond.