Artists who paint with their feet have unique brain patterns
smithsonianmag.com
smithsonianmag.com
However, being able to guess that painting with your feet leads to different brain patterns is much different than showing that it's the case. So the big deal here isn't that the brain patterns differ, but that we can detect the difference and that it's to some extent repeatable.
Becoming able to map specific brain patterns to specific abilities -- that's a big deal.
Taking https://en.m.wikipedia.org/wiki/Cortical_homunculus
As a starting point I think I could guess ahead of time that sensory maps might be distorted from the "norm", but
a) It think it would be interesting to see what moves to where and; b) How much this process differs between individuals; the remapping or densification could be highly idiosyncratic.
Leading to many other related questions from the article like:
a) What are the critical developmental thresholds for all this stuff? b) Is total area conserved if a person with fingers also uses their feet like this? What happens, exactly? c) Are nerves in appendages or spinal cord affected in any way by this process? (probably not right? but...) d) For people who suffer from phantom/ghost limbs, do their maps change over time? How? [EDIT: after a look around it seems like there are some interesting studies of this].
BOTH OF THE PEOPLE THEY STUDIED WERE BORN WITHOUT ANY ARMS. THAT'S A CONFOUNDER THE SIZE OF JUPITER.
They really need to look at people that have functioning arms, but choose to paint with their feet to see if this result still holds (but maybe with a smaller effect size). Someone that doesn't have arms can very plausibly develop maps that have nothing to do with painting. These guys have been using their feet as hands for their entire life. Is painting with your feet a couple hours each week enough to develop new maps (indicating that these mappings are very malleable), or do you have to go whole hog and stop using your arms entirely for these differences to be noticeable (indicating that the mappings are not as malleable).
That's basically questions a) and b) that you listed, but they are so fundamental that the study is sort of worthless without them. The remaining follow on questions can wait until we determine if this even generalizes to people with arms (which make up the vast majority of the human population). Because right now, we found out that a creative person with no arms has a brain that fires differently, and that's not really worth the cost of the electricity it took to do the study.
A "sensory map" does sound like multiple variables with tendencies.