Everyone knows that tickling often makes people feel particularly comfortable. A study in Japan reveals the deep mechanism behind this phenomenon, that is, tickling will activate the "reward system" in the brain, thus bringing people a comfortable feeling.
Hideyoshi Wang of Japan Institute of Physiology (NIPS) and others recently reported in the American Journal of Neurophysiology that they tested the responses of 16 healthy adult men and women in the tickling test. The subject's wrist is equipped with electrodes and feels itchy because of the current. When they tickle, researchers use functional magnetic resonance imaging (fMRI) to record the activities inside their brains.
The experimental results show that the striatum and midbrain in the brain react strongly when scratching, and these parts belong to the "reward system" that can bring people pleasure. Previous studies have found that this "reward system" in the brain is also activated when gambling wins a lot of money or is praised by others.
Some dermatitis patients often suffer from skin damage due to excessive scratching, and their symptoms are aggravated. Wang Yuexiuji said that this study confirmed the part of the brain related to tickling pleasure, and it is expected that by controlling this part, a treatment method to inhibit excessive tickling will be developed in the future.
Scientists finally solved the mystery of people scratching.
We all know that scratching can make people get rid of itching until they bounce back. Now scientists claim that they have finally found out why scratching always makes us feel more itchy. Studies have shown that scratching can cause the brain to release serotonin and aggravate itching. The research results of mice show that humans will have the same vicious cycle of itching and scratching as mice.
The study also provides new clues that may eventually help break this cycle-especially those who experience chronic itching. Scientists have known for decades that scratching can cause mild skin pain. Dr. Chen, a senior researcher and director of the Center for Itching Research at the University of Washington, said that pain can interfere with itching-at least temporarily-and transmit pain signals to the brain through spinal nerve cells instead of itching signals.
Dr. Chen said: "The problem is that when the brain receives the pain signal, it produces the neurotransmitter serotonin to help control the pain. She added that when serotonin spreads from the brain to the spinal cord, the chemical will jump out of the track-from neurons that feel pain to neurons that affect the intensity of itching. Dr. Chen said that scientists discovered the role of serotonin in controlling pain decades ago, but this is the first time to link this chemical messenger released by the brain with itching.
As part of this research, the researchers developed a new strain of mice lacking the serotonin gene. After injecting these transgenic mice with a substance that usually tickles their skin, these mice did not scratch like their normal compatriots. However, when transgenic mice were injected with serotonin, they showed the expected response after injecting compounds that induced itching. Dr. Chen said: "This is very consistent with the idea that itch and pain signals are transmitted through different but related channels."
"Scratching can relieve itching by producing slight pain. But when the body responds to pain signals, it actually makes itching worse. " Dr. Chen said that although the interference of serotonin makes mice less sensitive to itching, it is unrealistic to try to treat itching by preventing the release of serotonin. 5- hydroxytryptamine is involved in human development, aging, bone metabolism and emotional regulation. Antidepressants, such as Prozac, Zoloft and Paroxetine, can increase the level of 5- hydroxytryptamine, thus controlling depression.