In fact, the answer is pleasure, which drives us to pursue food and desire sex, thus evolving in survival, constantly multiplying and passing on family genes. Moreover, it is produced in a specific brain area of the brain, which we call the reward circuit, located on both sides of the front of the brain near the midline.
If you have a functional MRI scan of your brain when you are very hungry, this area of your brain will get excited when you take a bite of delicious food, and a strong signal of neuron metabolism will be displayed on the scan map. This means that every bite of food triggers the activity of nerve cells in the reward circuit.
As you feel objectively, not every bite of food brings you the same satisfaction. When you are more and more full, you won't feel that this kind of food is as delicious as before, which can be reflected in your brain activity. We will see that the first bite of food causes strong nerve activity, and then it gradually weakens.
Interestingly, more and more studies show that this kind of physical excitement, specifically the excitement in the brain region, is the driving force of people's behavior, not just the sense of morality, justice or virtue that we used to think. For example, why people are willing to help others, why they are willing to donate money and materials, and why they like charity. Psychologists believe that it is to make yourself feel good, similar to food stimulating the brain. Of course, excessive stimulation may lead to addiction, just like human beings are addicted to drugs, but why haven't you heard that some people are addicted to charity?
Although this is reasonable in theory, not everything can bring us the same pleasant feedback. For example, the addiction rate of nicotine in cigarettes is 30%, marijuana is 9%- 10%, heroin is 23%-25%, and alcohol is 15% 1. This is not to say that the remaining 70% or so people will not be addicted, but from the beginning of contact with these substances, you will become more demanding or dependent on these substances. It can be roughly seen from these pictures that these substances stimulate your brain to varying degrees.
Alcohol, nicotine, heroin and marijuana are addictive, while other substances, such as hallucinogens and some sedatives, are not addictive, because they will not stimulate the reward center, but will disturb other areas of the brain, which is related to their respective pharmacology.
Addiction is actually a learning process. This may not be easy to understand, so this time we should take the classic Pavlov conditioned reflex experiment as an example. In this experiment, every time you ring the bell, you give the dog a big piece of meat. When it comes to enjoying food, it will connect the surrounding environment with food, such as which room, who provides food, what kind of bell, what kind of smell, whether there is music around and so on. After repeating this connection repeatedly, it will equate these environments with enjoying food, so when you ring the bell again, even if you no longer provide food, it will still come happily, wagging its tail and secreting saliva, ready to have a big meal.
If you change the degree of this reward, such as from ordinary food to addictive substances such as cocaine, so that the degree of this pleasure is higher, they will be more willing to be constantly summoned and persistently return to the empty rice bowl, because they know that this reward is greater.
Smoking has the same brain reaction as people actually experience. A small cigarette brings pleasure to the brain, so you associate this pleasure with smoking. Nicotine is inhaled into the lungs, and as the circulating blood enters the brain, specific receptors feel this stimulation, releasing more dopamine into the reward circuit, making people feel happy. When this stimulus is repeated for years, it will change the expression and distribution of these receptors in the brain, and it will change you from a simple feeling of liking to a feeling of wanting, and then you will become dependent.
Back to the topic of driving behavior. Scientists have concluded that dopamine in the reward circuit leads to addictive behaviors, because when dopamine production is artificially blocked or destroyed, these behaviors will not be repeated. Because these substances that stimulate dopamine can no longer play a role in the reward circuit, the fun of these behaviors disappears immediately.
When it comes to addicts, we often evaluate their weak will: they can't control their behavior and lack willpower; Or having fun, especially enjoying gambling and sexual addiction. But in fact, many scientific studies show that some addicts become addicts because their genetic material carries different genes from ordinary people. The dopamine system of these gene carriers is weakened, so they can't perceive the normal level of excitement. For example, ordinary people may need to drink six glasses of beer to achieve the pleasure brought by drinking two glasses of beer, which greatly increases the probability of their addiction. This is not an excuse to become an addict, but shows us the powerful power of dopamine-driven behavior from another angle.