Although scientists try to be precise with language, they are often imprecise regarding the word "noise". Sometimes, noise refers specifically to that random jiggling, of thermal origin, that makes the signals we are looking for harder to see. But often, researchers use "noise" simply to mean signals they don't want, whatever their origin. And in fact, noise is a hot topic in functional MRI.
[P.S. NeuroCooking friends, thank you for staying with us as we reach this, our 200th post.]