Intelligence is generally regarded as the ability to solve problems, think abstractly and be flexible. Since the definition is "ability", intelligence is a very vague concept just like "physical strength", and different scholars have different definitions. But for an individual, intelligence is also easier to play well when the body is healthy, just like physical strength when the body is healthy.
In intellectual activities, we need to rely on the activities of a large number of nerve cells in the brain. Complex mental activities need to use cognition, logical judgment, language understanding, working memory and other functions distributed in various regions of the cerebral cortex at the same time. There are hundreds of millions of nerve cells in every brain region to coordinate their activities. Only when these areas cooperate smoothly and closely can the brain be used; When some neural circuits are not working properly, the whole system will be dragged back. For an individual, when he is healthy, his brain is more likely to be in the best working state and his overall brain power is stronger.
Many people have had this experience: when you need to rush to write an article in a sleepy state, you can't hold back a word, or you can't seem to write any ideas; If you are in good shape, you can be quick, if God helps you. The same brain, why is there such a big difference at different times?
The effect of neuromodulatory substances is very obvious and rapid. Many people will feel very tired when they are engaged in difficult and boring mental activities, and they can't persist. At this time, take a break, sing a song or run and jump, and the spirit will suddenly become cheerful and the work efficiency will suddenly become very high. This is because when singing or exercising, it will increase the secretion of neuromodulatory substances, dopamine and serotonin will produce a pleasant feeling, adrenaline can improve attention, and acetylcholine will increase the degree of wakefulness. All these will improve people's cognition, recognition, concentration and short-term memory in a short time, and better carry out creative mental work.
For different individuals, there is a complex relationship between health and intelligence, but many people with serious diseases may have superior intelligence. For example, Hawking, a great contemporary physicist, has been troubled by severe lateral sclerosis of the spinal cord, but this serious health problem has not damaged his intelligence. Hawking has more time to think alone because he is inconvenient to move, so he thinks deeply about problems than most people who move freely.