Since my new book, The Body Has a Mind of its Own: How Body Maps in Your Brain Help You Do (Almost) Everything Better arrived I've been buried in it. The Blakeslees have written a very good book, (even if they didn't include a reference list).
Ginger Campbell MD has an excellent podcast about this book. Visit her show notes here.
This book, and for those in a hurry, the podcast, affords us a long leisurely look into the brain and its workings (especially after having just read Rhythms of the Brain!) The brain creates several maps, mostly in the parietal lobes, mostly of the body itself (the human antigravity suit itself, inside and out) but also of the space around the body - it will change the maps to include any tool that is being used, for example, a cane used by a blind person to navigate along a street. The kinesthetic/motor map stretches out to include the cane, spreads over the visual cortex, and enables the person to "see" the sidewalk through their body.
The brain turns on as soon as it forms embryologically, starts to function even as it still grows (the frontal lobes are not fully grown for a couple decades), and does not ever turn off until the moment we die. Even while we are sound asleep, it is still working away, keeping our lungs breathing and our heart beating. Amazing. First there is movement, then through feedback from the movement and subsequent encounter with the environment, the brain refines its maps of space and how the body fits into them. Strokes and other neurological twists of fate can lead to some very strange mapping problems, like the feeling of having three arms, or only one, or that a limb does not belong to one and must be amputated.
Of interest to me as a manual therapist is a careful and lengthy explanation of various dystonias and what is thought to happen to the mapping in association. Stress-free practicing of any honed motor skill is advised; just practicing mentally (e.g., golfing) will preserve mapping with good fidelity - the brain will use premotor maps, so no need to burn out your actual motor maps. Musicians will find this an important book to read, sports enthusiasts, anyone who uses their body for skilled performance of any sort.
When I think about how I use my own body, I realize I'm not apt to incur dystonia over time. For one thing, I don't rush, and for another, I never do the same thing twice, the same way, ever.