Have you ever suffered an injury and noticed your immediate reaction is to grab the area or rub it? Why is that instinctive, and how could that possibly give us relief?
In 1965, two researchers by the names of Ronald Melzack and Patrick Wall proposed a theory of pain modulation called gate control theory. It states that the transmission of nociceptive information (aka, pain) is modulated by mechanoreceptors that perceive non-painful sensory information (aka, touch). Thus, regular non-painful sensory input can “close the gate” to painful input and therefore prevent the transmission of pain to the brain.
This “gating” happens at an inhibitory neuron located between the two pathways. That local neuron essentially receives excitatory information from the touch pathway and uses that to inhibit the pain pathway. The figure below is a great visual of what’s happening. The touch pathway is the top (maroon) one, and the pain pathway is the bottom (dark blue) one. In between the two is the inhibitory (light blue) neuron. When the touch pathway is activated (i.e. when you rub your stubbed toe), the mechanoreceptor activates the local inhibitory neuron, which in turn inhibits the signal coming from the pain pathway.
How cool is that? We have a built-in mechanism for reducing the perception of pain. So, next time you stub your toe on that tricky chair leg (who put that there?!?!), let your body react the way it initially wants to by activating your touch pathway!
Source (photo and content): Neuroscience, 4th edition textbook, by Purves.