I and one other guy I know have a problem with this mechanism..  he had a lot of testing down, and doctors told him it was all in his head, I just ignored the problem and worked around it. when first trying to eat or drink something, it is not uncommon that I'll have trouble swallowing... and then my sinuses will start to run. My friend has the same situation exactly. the odd thing is, we are both like camels...  we don't need to drink much, even when working in hot conditions. It would be interesting to know if this swallowing prevention neural mechanism now has a name, so that I can follow developments with it.