The Science Behind Pain
“Pain is weakness leaving the body.” Sometimes I think that quote is pretty accurate, such as when I am on a run and my legs are burning but I can tell that I am getting stronger. Other times, like when I face plant on concrete, that statement could not seem less true— “that’s not weakness leaving my body, that just f****** hurts.”
So, what is pain? Where does ‘pain’ even start? And why do you feel it differently than others?
You have billions of nerve cells, called neurons, in your body. Certain nerve cells, called nociceptors, sense potentially harmful stimuli like heat, pressure and open wounds in your peripheral nervous system (every part of your body except for your brain and spinal cord).
These peripheral nerves send electrical signals all the way to the spinal cord and then up to the brain to get processed. There are primarily two different types of nociceptor nerve fibers, some carry signals faster than others, which explains why some pain is sharp whereas some pain is dull and non-localized.
These electrical impulses first arrive at the thalamus—which is like the post office of your brain—determining where messages get sent to next. From there, these signals are sent out to the ‘pain neuromatrix’ of your brain, different parts of the brain including regions of your cortex, the amygdala and hypothalamus, that all play a role in processing these electrical signals.
After your brain processes the incoming stimuli, it sends out signals to your body such as telling your muscles to move your hand away from the campfire or stop walking on your foot that you just broke.
This is where things get interesting…
While pain has physical components—external stimulus sending a message via neurons to your brain—it is an emotional process. Pain is subjective. People’s brains are different, so they process pain differently. If you give two people the exact same painful stimulus, their perception of it could be extremely different—one person might not even flinch while another might scream.
Evolutionarily speaking, pain is a crucial element for our survival. If our brains didn’t notify us that something was harmful, like if you had a knife in your thigh and might bleed out, then we would likely die. This is ironic, because we are programmed to pay attention to parts of our body that are in pain, but attention to pain has actually been shown to make it more intense.
The term ‘cognitive appraisal’ refers to how you think you can handle pain. Your ventrolateral prefrontal cortex is activated when you think you can control your pain—whether or not you can—and this is associated with lower perceived pain intensity. So basically, if you believe you can cope with the pain, it won’t seem as bad.
Emotion plays a huge role in pain perception. It has been shown that sadness, anger and fear all exacerbate pain—because those emotions have connections to the same parts of your brain that are associated with processing pain. So thinking negatively, will likely only worsen your pain. And anticipating pain can actually make an experience more painful.
There is no doubt that pain is partly physical in nature. But the mind plays a large role in how you process such physical sensations, making it an emotional experience too. Perhaps sometimes it is weakness leaving the body…perhaps you are getting stronger by learning to cope with it and telling yourself that you are capable of handling it. Of course, some things simply hurt like hell, and no amount of cognitive energy can completely diminish that.
But next time you’re in pain, and you’ve checked to make sure it isn’t life threatening (that is where pain is a useful tool…), see if you can trick your mind in to coping with it a little better. We often underestimate the power of the mind, but it is amazing what it can do.
Cheers,
AT
Sources:
A good quick video:
https://www.youtube.com/watch?v=I7wfDenj6CQ
Scientific review:
Garland E. L. (2012). Pain processing in the human nervous system: a selective review of nociceptive and biobehavioral pathways. Primary care, 39(3), 561-71.