If you close your fingers in a car door or slap your funny bone into a wall, your first reaction may be to pull on your fingers or rub your elbow. Not only is this an instinctive self-deprecating behavior, it is a very effective tool for setting pain signals to the brain for a period of time.
But how and why does it work? To understand, you need to know about the main theory of how pain is communicated in the body.
In the 17th century, the French scientist and philosopher René Descartes suggested that there were specific pain receptors in the body that “rang a bell in the brain” when stimuli interacted with the body, Lorne Mendell, professor of neurobiology and behavior at Stony Brook University in New York, tells Mental Floss. However, no effective study of receptors has been identified anywhere in the body that responds only to painful stimuli.
“You can activate some nerve muscles that can cause pain, but in other cases, they don’t,” Mendell says. In other words, the same nerve fibers that carry pain signals also carry other sensations.
In 1965, two MIT researchers, Patrick Wall and Ronald Melzack, proposed what they called a pain gate control theory, which, for the most part, holds up to this day. Mendell, whose research focused on pain neurobiology and worked with both men on their pain studies, explains that their research showed that feeling more pain is about stimulus balance on the different types of zero muscles.
“The idea was that certain threads that increased the intrusion were ones that opened the gate, and those that decreased the intrusion closed the gate,” Mendell says. “So you have this idea of gate control sitting all the way into the spinal cord, and that could be open and take out pain, or the gate could to close and reduce pain. “
The gate control theory was unveiled in 1996 when neurophysiologist Edward Perl discovered that cells contain nociceptors, which are neurons that indicate the presence of destructive stimuli in tissue or fine-grained damage.
Of the two main types of zero fiber – large and small – the large fibers carry non-nociceptive (painless) information, while small fibers transmit nociceptive (pain) information.
Mendell explains that, in studies where electrical stimulation is applied to nerves, as the current is built up, the first fiber stimulated is the largest. As the intensity of the stimulus increases, fewer and fewer fibers are recruited. ”When you do this in low-grade patients, the patient will recognize the stimulus, but it will not be painful. , “he says. “But when you increase the intensity of the stimulus, you eventually reach a threshold where the patient suddenly says, ‘This is painful.'”
So, “the idea was to close the gate was something the big threads did, and opening the gate was something the little threads were doing.”
Now back to do pain. When courting a jammed finger or rubbing a banged shin, you stimulate the large fibers with “counter irritation,” Mendell says. The effect is “a decrease in the message, or the size of the block of signals transmitted over incoming root activity. You basically close the gate. It is that reduces pain. “
This concept has created a “big business” around treating pain with mild electrical stimulation, Mendell says, with the goal of stimulating these large threads with the hopes of closing the gate on the pain symptoms from the small fibers.
While severe humiliation may not help pain with a serious injury, it may come in the next time you get a bad bruise or toe.