Itch, also known as pruritus, is an uncomfortable sensation in the skin that evokes the desire to scratch. While scratch happens to be an innate reflex that may occur in the absence of the brain, Dr. Zhou-Feng Chen of Washington University School of Medicine Pain Center says itch is “a perception that comes directly from the brain.”
Itching can be caused by a number of factors such as dry skin, aging skin, insect bites or stings or disease. Also, while some cases of itching can be psychosomatic, some can be contact dermatitis such as when your skin comes in contact with poison ivy or poison oak. So why does it itch when a mosquito bites you or when poison ivy touches you?
Well, the guy(s) at Life Noggin, explain(s) it in one of their videos – Why Do You Get Itchy? For a while, scientists thought that itching and pain were detected by the same nerve cells and then interpreted as different sensations in the brain. However, that’s not actually the case, granted there is a class of nerve cells called C-Fibers that can detect pain, itch and heat, but that class has a specialized group that we can blame our itchiness on, explains Life Noggin. Essentially, when a stimulus like histamine activates one of these nerve cells, a signal is sent to the spinal cord and up to the brain. Here, the signal is processed in the somatosensory cortex and you experience an itchy feeling.
Also, do you know why does scratching an itch make it worse? It is because when you scratch, it triggers the brain to release serotonin, which makes you to itch more. Scratching an itch is really bad and although scratching relieves itches, it is just for temporary. The video further notes that itching can be contagious and watching someone scratching activates the same part of the brain as scratching yourself. So what started as a way for our ancestors to get dangerous insects off their body, has now become one of the most frustrating sensations we have to deal with it, especially if it is in “the middle of your back.” Watch the video below and tell us in the comments if it makes you itch.