On page 32 of the November/December issue, Seed Magazine reports that in July of 2007
Neuroscientists seeking to discern whether culture affects the human brain examined those of a group of Americans and Nicaraguans as they watched different hand gestures specific to their respective cultures.
Hopefully, this is not what said neuroscientists (no reference is given) were actually trying to do, because fMRI is very expensive (it typically costs hundreds of dollars an hour just to rent the machine), and you wouldn’t really need to do an experiment to answer this question.
I think it’s fairly obvious that people respond differently to language-specific hand gestures (for one thing, they are more likely to respond to them). If people respond differently, then their brains should also respond differently. To suggest otherwise means that you believe that the difference in behavior is due to either (1) an immaterial soul that controls that can engage in activities independently of the body, or (2) these behaviors are controlled by some organ of the body outside the brain.
These are both logically possible hypotheses, but the research over the last few centuries makes them so unlikely to be the case that unless you have a really, really good reason to suspect that the brain is not involved in interpreting hand gestures, then it’s not really worth the incredible cost of fMRI to answer this particular research question.
Seed is a decent, informative magazine, so the fact that they let this slip is just more evidence of how pervasive this thinking is.