One could take this further and claim that even the most rudimentary mathematical construct, the integer, is in the eye of the beholder. Counting relies on certain perceive regularities: "boundaries" that allow us determine where a the "identity" of an object, and "similarities" that allow us to group together objects into counts.
The concept of an integer seems to presuppose the concepts of identity (or distinctness) and regularity (for want of a better word). Whether all types of neurologies will have the same ideas of identity and regularities (or objects and classes?) and therefore the same concept of integers, is something that we probably could not imagine because we can't step out of our own neurologies...