Let’s imagine that your brain is an industrial city. A hive of activity. Areas of the brain are separate little factories, and each little factory is responsible for manufacturing certain goods or coordinating specific services.
There are some certain factories that have a sideline in processing pain. If we are lucky, they are only called into action to do this every now and again, in acute pain. In acute pain, extra factory workers (known as neurones) are recruited temporarily from their usual activities to undertake the sideline tasks of processing and managing pain. Because these workers are taken from the main factory tasks, the other outputs and purposes of that factory temporarily slow down or stop. Fortunately, in the short term, there is minimal disruption to the usual factory purpose. After acute pain dies down, it goes back to business as usual at the factory.
But what happens when the pain continues, stealthily moving from acute to chronic pain? What happens when those factories are called on to process pain more and more?
Well, simply put, the sideline job takes over from the main goods production. More and more of the factory workers (neurones) are recruited to manage the influx of pain messages. More and more of the factory floor (brain space) is dedicated to managing pain, and less space is allocated for producing the main goods of each of the factories.
Factory processes (neural pathways) are altered to focus on pain, taking the emphasis away from business as usual. In short, the sideline becomes the main job.
Frequent or constant pain messages wire up the brain to dedicate more and more space to processing pain. In acute pain, only 5% of space in relevant brain areas is dedicated to pain-processing. In chronic pain, however, that goes up to 15 to 25% of the space in those individual factories.
But, what do I mean by the “relevant” brain areas? Well, not all of the brain processes pain. Finding out which areas of the brain are involved in processing pain gives us a clue as to how to fight it.