Monday, July 19, 2010

Cortical processing of somatosensation

I wrote here about a conversation I had with Paul Hodges of PT motor control distinction, while bumping around in a minivan and while enjoying fabulous food and drink in Brazil. If only I had had this series of slides at that time, there might have been less quibble. Anyway, I found materials and have made them subsequently for a talk I'm giving this coming weekend called "Have we left the skin out of manual therapy?" in which we'll be presenting the results of our pilot project measuring the effects of skin stretching treatment on pain. The two sources for this 7-slide segment were:
1. Smith CUM; Biology of Sensory Systems
2. Keysers C; Somatosensation in social perception

Points to ponder:

1. It would appear there are 4 functioning somatotopic maps up there, not just one.

2. It looks like only one area (about 25% of the cortical real estate dedicated to somatosensory processing), BA3a, deals directly with muscle spindles. The other 75% directly deals with tactile (exteroceptive input) and secondarily with whatever BA3a has already processed.

3. Each of the tactile processing areas deals with a specific sort of mechanosensitivity.

4. It looks like (to me, at least for the moment) that the brain is more concerned (based on how much of its cortex is involved) with somatic exteroception than with somatic (muscular) interoception; might this relate to examining potential threats from the environment?

5. According to the Keyser paper a lot of socially evaluative areas pour their information into the mix as well.

6. As a manual therapist I'm concerned with creating an environment and a therapeutic relationship in which all social threat is reduced, and in which a non-nociceptive, non-noceboic, kinesthetic input will be "added," so that the brain has something to work with to down-regulate pain felt in a "region," while otherwise permitted to be peaceful/safe. I think this information provides a bit of science base to support that inclination.

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