The Neuroscience of Pain

Are feelings in the body or the brain?

We know that thoughts and emotions are rooted in our brain. But our experiences of the external world – touch, smell, sight, pain – depend on the brain too. For example, some people with spinal injuries can touch things without ‘feeling’ them. This happens because the nerves send signals that the brain is not receiving or is unable to interpret. The opposite happens with phantom limb pain. More than 80% of people who have lost an arm or leg still feel that missing limb. The brain is generating feelings with no stimuli coming from the outside.

When it comes to pain and sensation, the brain rules.

Why do we feel pain?

Pain hurts – it is an unpleasant sensation. That’s exactly why ‘acute’ pain – pain we feel when we hurt ourselves (cuts, bruises, or broken bones) – is helpful (p. 100). First, pain alerts us that we are hurting ourselves so we stop. Second, pain teaches us to be careful. You know that old saying “Once burned, twice shy”? Pain teaches fast.

Patient: Doctor Doctor it hurts when I do this.
Doctor: Don’t DO that!

What do emotions have to do with pain?

All pain is in the brain. We experience healthy, acute pain when the brain senses tissue damage.

How does this happen? A stimulus activates receptors in the tissue (you fall and skin your knee, triggering specialized nerve cells). These receptors send signals to brain through nerves and spinal cord ( process called nociception). When the signals reach the brain, they are interpreted and given meaning. Will we experience pain then? It depends.

  • IF the signals are sufficiently strong and
    • IF the brain may think the body is in danger,
      • THEN we experience pain (p. 32)1.

If you fall, many signals are sent from your knee to the brain – pressure, tearing, wet. This can be automatic (the strength of the signal immediately signals damage, you flinch even before you know what happened, then you feel pain).

It can also be influenced by what you know. If you see blood, it can change whether your knee feels tickly, weird, or painful.

Strong physical sensations also triggers a whole cascade of emotional reactions that can change what we feel.  For example, some runners interpret their pounding hearts, struggling lungs, and screaming muscles with satisfaction (‘Pain is weakness’s way of leaving the body!’)

That’s in the context of running. If they woke up from a sound sleep with those sensations, they might experience them as fear (I had a nightmare!) or as pain (I’m having a heart attack!) and head to the emergency room.

Strong sensation is felt as pain if it is threatening.

The role of the amygdala

The amygdala is part of the brain central to feelings like fear, anxiety, and anger. It also processes punishments and rewards. Burning your hand quickly teaches you not to touch fire. Rewarding experiences make it more likely we do something again. If you had fun at an amusement park, you’re more likely to go back.

An amusement park is a good example of how the amygdala can change how we feel – and thus the power of rewards to change behavior.  

Think about how it feels to go ride a roller coaster. What makes it fun for lots of people is the thrill. We feel danger from the speed and sensation.  Despite that, we also feel pretty safe because the precautions and seat belts and seeing other people laughing as they get off the ride damps down our fear.  Both the fear and the pleasure feelings we experience on a roller coaster are mediated through the amygdala. If we didn’t trust the amusement park, a roller coaster wouldn’t be fun, it would be terrifying.

The amygdala’s response differs by context

Have you ever ridden a roller coaster by yourself? It’s a lot more fun with a buddy. Most people – particularly teenagers – have much more fun doing risky things when they’re with friends. That’s because being with others activates the amygdala and enhances feelings of reward. This even happens when we just think our friends are watching or if we imagine sharing what we’re doing on Instagram or Facebook.

The same is true of pain.

We experience sensations very differently depending on what emotions go along with them. When we are depressed, scared, or anxious, the amygdala interprets injury and sensation as threatening. What happens?

Everything hurts MORE.

The effects of negative emotions on pain are incredibly powerful. One reason that painkillers like opioids work is by turning down the fear receptors in the amygdala.

Parenting Tip: The article Teens Respond To Pleasure Not Pain, Parent Accordingly applies this principle to parenting.

Is that why distraction helps?

Yes!

It seems impossible that someone in pain can be laughing and playing a videogame one minute, then overwhelmed and unable to set the table or focus on homework. But it happens all the time. The positive emotions and activation of the brain – plus the conscious focus on the activity instead of the pain – changes how pain is experienced.

That’s not faking it. It’s neuroscience.

The role of the amygdala in pain is one reason most pain professionals recommend people in pain work hard on getting out and seeing people, meditate or exercise to reduce their stress levels, and get treatment for depression and anxiety.

When you feel the world is a safer and less threatening place and that you are more powerful and capable, the same sensation is interpreted differently.

When you’re having fun, the anxiety and danger centers of the brain ratchet the experience of pain way down. The pain is still there, but it’s much easier to deal with.

Parenting Tip: Doing enjoyable things – art, video games, sports – gives kids a break from pain so they have more energy for schoolwork and chores.

In other words, when you feel happy and strong, pain hurts less.

What is chronic pain? What helps?

Why do I hurt all the time?

Healthy pain is like a good guardian. It keeps you from hurting yourself and teaches you to stay safe. This type of pain is called ‘acute pain’.

Unfortunately, sometimes the acute pain system becomes too sensitive and overprotective. When that happens, you perceive pain as if you were injured, even though you’re not. This unhealthy state is called ‘chronic pain’. What is injured isn’t your tissues, but the nervous system itself.

Sometimes people experience chronic pain because they have been injured. For example, breaking an arm causes immediate acute pain. Sometimes, however, the pain persists or gets worse after the bone and injury are healed. This happens in complex regional pain syndrome. The very real pain is not caused by the break, it is caused by signals in the injured nervous system becoming amplified like sound in an echo chamber.

In other cases, there is no initial injury. Pain is caused by an underlying illness or disorder. For examples, people who have migraines often experience allodynia. In allodynia, normal sensations like light or sound or gentle touch cause extreme pain. In this case the nerves and brain are over-reacting to external stimuli and reacting to them as if they were harmful.

And, of course, lots of times you get combinations of acute and chronic pain. In conditions like irritable bowel syndrome, tissue inflammation and neurological problems can both cause pain. One of the reasons it can be so hard to treat chronic pain conditions is that pain can persist even after the original problem is in control.

I’m in pain. Shouldn’t I rest?

When you hurt yourself – sprain an ankle or ache all over because you have a cold – rest is the best thing for you. Your body needs rest and time to heal. When you finish healing, your pain goes away.

In chronic pain, that doesn’t work. There is no injury to your tissues, so resting won’t help. In fact, it can be harmful. If pain becomes chronic, bedrest can cause your muscles to become weak very quickly, causing its own very real pain. Overusing over-the-counter pain killers can also lead to ‘rebound headaches’, where people experience headaches BECAUSE of the medications they are taking to reduce pain.

Spending too much time in bed can also be very isolating. Alone with nothing to think about except how you feel, it’s easy to become lonely or depressed. Anxiety can creep in too. If you start to worry about the schoolwork you’re missing or things left undone, it raises your stress level. Because emotion and pain influence each other so strongly, it is easy to get into downward spirals where pain feeds stress, anxiety, and pain and they make the pain worse.

If you start worrying that pain will get worse if you get up and get out – or if pain DOES get worse when you get up and get out – it’s easy to wind up in a really bad place.

That’s why getting moving – even if it’s just from the bed to couch – is so very important.

Spoonies” have to plan carefully to do what’s most important to them because the know they’ve only got so much energy before they need to rest.

It takes a lot of energy and discipline to get out and maintain a normal life when you’re in pain. Christine Miserandino wrote a great essay explaining what it’s like, The Spoon Theory, for her blog But You Don’t Look Sick.

The 1step2life team is writing away, providing the best content and resources we can to help teens in pain and their families. Check back soon.