Can you or anyone explain how what the neurons are doing is "calculus"?
Calculus is how we scientifically communicate nature to each other, not away for nature to implement mathematics. Flies are not doing calculus any more than you catching a thrown ball is doing calculus. This headline, and perhaps the grant proposal, is written for stupid people. I hope this explains it for you.
"There are things that are so serious that you can only joke about them" - Heisenberg