Any of our feelings or emotions – in essence, any psychological sensation – is based on brain activity. The fact that the brain, this physical entity, is the basis of mental activity, gives us the key to understanding the mechanism of action of chemically active substances (drugs) on mental processes.
All psychoactive substances produce their effect by acting in different ways on the tissues of the nervous system, and this chapter is devoted to such physiological effects of drugs. Most of these effects occur at the level of the brain.Recently, many significant discoveries have been made in the sciences that study the brain, shedding light on the mechanisms of the functioning of the brain. In parallel with these successes, our ability to study the effects of drugs on the body is increasing. There were fundamentally new approaches to solving problems such as addiction to drugs. However, before discussing the effect of drugs on the brain, one should consider the basic principles of the brain.