We touched on the Gate Control Theory in the last post. The spinal cord and the brain have the ability to act like a "gate" and control the flow of information that is received or sent from it.
Your body has millions of these sensors that are constantly sending messages to your brain about the current state of your body. Some sensors or nociceptors, respond to hot or cold, some to stress and others to movement. Other sensors only respond when things are getting dangerous - too hot, too much stretching or physical damage, and they trigger a danger message.
These sensors send danger signals in the form of electrical impulses from the body to the spinal cord via nerves for further processing. The spinal cord is kind of like a switch board operator. It can decide to send the signal up to the brain, or it can decide to leave the signal at the spinal cord which mean the brain doesn't get the message that there is potential danger.
The spinal cord is the first place that can change the messages before they get to the brain.
There are a few reasons for this - first, the danger signals must be strong enough to open the gate to the central nervous system. Or, If other
nerve signals are sent that mitigate the danger signal, the signal will not be sent to the brain.
We know that there are at least two types of nerve fibers that carry the majority of danger messages to the spinal cord:
- A-delta nerve fibers, which carry electrical messages to the spinal cord at approximately 40 mph ("first" or "fast").
- C-fibers, which carry electrical messages at approximately 3 mph to the spinal cord ("slow" or "continuous").
Example: If you hit your elbow or your head really hard, you immediately start rubbing the area to provide some relief. This activates other sensory nerve fibers that are even "faster" signals that send information about pressure and touch. When these signals reach the spinal cord, they can override the messages carried by the A-delta and C-fibers. The interaction of these different sensory messages can directly inhibit the effects of the nociceptive fibers and close the gate to the transmission of danger to the brain.
The action of these other types of nerve fibers helps explain why treatments such as massage, heat or cold therapy, TNS (transcutaneous nerve stimulation), and acupuncture are often effective in treating pain.I hope you enjoyed this interesting byte of pain science and that it helps change how you think about your pain!