One non-measuring idea is to gradually replace portions of the brain with artificial blanks, relying on some sort of holistic (or holographic) redundancy where the "damage" is repaired by neighbors.

This, er, Brain of Theseus would retain operational patterns even if the individual cells have been replaced.

A variation on that would be too do it stochastically, constantly substituting a miniscule percentage of cells evenly across the entire brain.