Correlating brain states with psychological phenomena

The correspondence hypothesis is a conjecture to the effect that psychological phenomena correspond (in a one-to-one fashion) to certain states and processes in people's brains.
It suggests that for each and every (different) psychological phenomenon that a person has at any given time there is a different state or process in his brain with which it is uniquely correlated.
This hypothesis, often referred to in philosophical literature as 'The Principle of Psycho-Physical Isomorphism', is purported to provide the empirical foundation on which a variety of conflicting mind-body theories are constructed as well as the Riddle which such theories aim to unravel.