A region of the brain dubbed the ‘Ouch Zone’, responsible for the “it hurts” sensation has been discovered by scientists at the University of Oxford and could be used to help understand if someone is in pain even if they can’t communicate.
For almost half a century scientists have been trying to pull apart all the components that contribute to the feeling of pain, which has proved very difficult due to the explosion of brain activity that occurs.
Pain is a very complex experience. Our brain not only recognises that we are in pain and what part of the body is involved but also produces emotions of anxiety or fear and draws on memories of when we’ve been in pain before. This evolved to help us deal with pain but makes the job of finding all the pieces of the jigsaw rather difficult for scientists.
Now, for the first time, with the help of new brain imaging technology Dr Andrew Segerdahl and colleagues, writing in Nature Neuroscience, have managed to tease out the area of the brain involved with pain intensity, called the dorsal posterior insula.
Sergerdahl subjected participants to a painful stimulus, a cream containing capsaicin, the active ingredient in chillies. The sensation starts off quite tolerable with a warming feeling, which then becomes rather painful and stabilises for a while, before subsiding as the participant gets used to it.
While this rollercoaster of pain was going on, Segerdahl used a brain imaging technique called Arterial Spin Labelling (ASL), which is able to track in real time the amount of blood flowing to different areas of the brain.
"As your brain is working, different parts of the brain need oxygen to be active and arterial blood is the main delivery system" explains Segerdahl. By tracking blood flow in the brain during a pain experience they were able to look at what brain regions were most active.
Segerdahl identified the dorsal posterior insula as responsible for pain intensity as it mapped the pattern of pain ratings given by the willing victims during their chilli exposure. They saw a much higher volume of blood in the dorsal posterior insula when the chilli cream was at its peak pain intensity compared to when it was first applied or as the pain started to ease off.
Identifying the brain region responsible for pain intensity could be very helpful for people who can’t communicate how much pain they are in. “I'm thinking about infants, those in a comatose state or those experiencing dementia” says Segerdahl. We may also be able to tell if a pain relief is working even if the person can't tell us so.
Next on the teams to do list is to find out if we can treat pain by targeting this brain region.