August 12th, 2015

     Modulation

This is when the brain processes the nociceptive information coming in and assesses how threatening it is to the body.  It needs to answer:

1)      What does this mean

2)      What will be advantageous

Taking Bethany Hamilton (again) for an example, the answer to the first question was obvious.  What would have been advantageous was that she got out of the water as fast as she could (which she did) and got the help she needed as soon as possible. If she had stayed in the water, she would have bled to death, never mind getting the shark in a frenzy. This is called descending inhibition (this will be discussed in a later blog post).

Any credible evidence of danger to your body will modulate Pain. This time, for her, the danger was not the shark bite, but, rather, the danger of bleeding to death in the water. Therefore, no Pain, or minimal Pain.

The next time she got in the water, she may well have excruciating pain from a scratch by a piece of seaweed. This is because Pain depends on how much your brain thinks you are in, not how much danger you are really in. So, the input from the scratch by the piece of seaweed would have travelled up into the thalamus, routed to the cerebellum, frontal cortex, limbic system. The situation would be assessed by these parts of the brain, and, drawing from the previous experience of the shark bite and nearly bleeding to death, the brain would have sent out a great Pain output, as this time, the meaning would be different.