The Brain Can Learn To Decrease Pain

New research led by Raymonde Scheuren from the University of Luxembourg has brought some new insights into the world of pain. It’s generally known that a pain present in one part of the body can be attenuated by painfully stimulating a different part of the body. This is known as diffuse noxious inhibitory control (DNIC) and is thought to take place to allow the body to focus on the new, and potentially more important, threat to the body.

In their experiments, Scheuren et al. caused pain in subjects by electrically stimulating a foot. They then created a second source of pain by placing the opposite hand in a bucket of ice-cold water. As predicted, after the hand was immersed in cold water, the pain from the foot decreased. The interesting part of the experiment was when the insertion of the hand into cold water was repeatedly coupled with a phone ring tone. Afterwards, simply playing the ring tone (without placing a hand in cold water) was enough to decrease foot pain from the electrical stimulation! Conditioning had taken place. Conditioning is a form of learning where the physiological effect of a stimulus (ice-cold water) is reproduced by an unrelated stimulus (phone ring tone) by having the two repeatedly happen simultaneously. The one takes on the effect of the other.

The reverse effect possibly plays a part in chronic pain. Sights, sounds, smells and other sensations that were present during the traumatic incident that caused the injury can unconsciously become triggers for pain long after the injury has healed.

Case Study

Something interesting happened last week whilst I was treating a client. He was referred to me a few weeks back because of hip pain. About 18 months ago a car knocked him off his bicycle and he landed on his right side, after which he immediately noticed right hip pain.

He has been gradually improving with treatment…so far nothing remarkable but during our last session he mentioned that the travel anxiety he had experienced (I didn’t know he had anxiety) since the accident had also been getting better. He said that the anxiety was lessening as the pain decreased…wow!

What could explain the connection between the hip pain and the travel anxiety? Well, to answer that we need to go back in time to a famous psychological experiment…Pavlov’s dogs…ring any bells? In his experiment, Pavlov rang a bell before feeding dogs. After a while he noticed that the dogs would salivate at the sound of the bell…without the presence of food! The dogs had associated the sound of the bell with food. This process is called conditioning. It takes a while to establish itself and dissociating the bell from food can extinguish it i.e. if you stop feeding the dogs after ringing the bell, they’ll soon stop salivating when they hear it. A similar phenomenon can take place almost instantly during significant emotional events. Sights, sounds, smells and others sensations can unconsciously become associated with the event. Emotionally traumatic experiences can create phobias…amongst other things. A phobia is an irrational fear of an object or situation.

In this case the fear or anxiety is linked to the client seeing cyclists among circulating vehicles. Presumably, in these circumstances, the hip pain has also become a trigger for the emotional response. Therefore, it’s no longer surprising that as the pain has decreased with treatment, so has the emotional response to cyclists.

Fascinating isn’t it? The complexity and beauty of the mind-body connection never ceases to amaze!