Every time you perform basic survival behaviors, such as eating or having sex, the brain’s reward center releases dopamine, a neurotransmitter that provides pleasure and the desire to repeat the experience.
Well, most drugs are capable of activating the same brain area and multiplying pleasant sensations by up to ten times , which affects motivation, self-control or morality. Thanks to modern neuroimaging techniques, scientists increasingly know which parts of the brain are stimulated by drugs and why they produce such different effects.
Cocaine
That cocaine addicts stop being masters of their own actions has a neuroscientific explanation. In the prefrontal cortex, there are centers related to self-control, attention and decision-making that deteriorate and decrease in size when this drug is consumed.
On the other hand, using magnetic resonance imaging , researchers from the University of New Mexico showed that the anterior cingulate cortex, necessary for making moral decisions and showing empathy, is also reduced in activity. And that makes it difficult to distinguish between what is right and what is wrong.
Marijuana
Every time you are about to have a rewarding experience, the neurons of the nucleus accumbens boil and release a jet of dopamine , the pleasure hormone. The more dopamine, the more pleasant the sensation is. However, this becomes almost imperceptible when we assiduously consume marijuana. So much so that, in the long run, smoking joints chills enthusiasm and stifles positive emotional response to any stimulus.
Unable to feel satisfaction, its consumers can lose interest in almost all activities, which is known as anhedonia. They are only stimulated by the drug itself, as the reward centers respond more and more strongly to it. It also acts on receptors in the amygdala , the brain center of the limbic system that regulates fear. Generally, it attenuates neural signals in this area, which calms down anxiety. But, in other cases, it overexcites her and paranoia appears, so that any normal experience can become frightening.
LSD
Researchers from Imperial College London demonstrated that, after consuming lysergic acid diethylamide (LSD), a lack of coordination occurs in neurons of the sensory cortex that causes cells that should be activated at the same time to become desynchronized, while overlapping the signals of others that were to come on at different times. This chaos could explain why LSD alters consciousness. In addition, alpha waves in the brain are reduced, leading to hallucinations associated with their consumption.
Ketamine
In places where electronic music is played and at rave parties, one of the most popular synthetic drugs is ketamine. According to neuroscientific studies, it acts directly on the infralimbic cortex of the brain, which modulates mood . This gives it antidepressant properties. On the other hand, by reducing the transmission of glutamate, it prevents the brain from having a correct representation of its own body and its movements, which explains the sensation of floating outside the body.
Psilocybin
This drug, present in psilocybin mushrooms, owes its effects to the fact that it reduces blood flow in the central area of the brain , especially the thalamus and the anterior and posterior cingulate gyrus, related to consciousness and personal identity. Hence, psilocybin makes us experience strange bodily sensations and an altered state of space-time.
Ecstasy
Although popular with young people between the ages of 20 and 35, colored pills, or MDMA, are far from safe. As a recent German study proved, its consumption causes serious memory problems due to its effect on the hippocampus , the part of the brain responsible for forming and retrieving memories. It also interferes with the transport of serotonin, related to mood and sleep. This means that consumers do not know how to choose the appropriate emotional reaction to each situation.
Heroin
Either injected or inhaled, it is converted to morphine upon reaching the brain. There, it attaches itself to opiate receptors in the brain stem and in areas related to pain perception. The consumer enters a state of torpor in which all kinds of physical and mental pain disappear. It also causes a drop in brain oxygen levels , causing irreparable damage. This explains the weakness, tremors, spasms and, in extreme cases, cerebral infarction and Parkinson’s typical of heroin addicts.
Image: healthy brain (left) vs. brain of a person with a methamphetamine addiction (right). National Institute of Drug Abuse (NIDA).
