Our current understanding of mental processes in health and disease is
limited by the absence of a practical model describing the physiology
of the mind as an informational system. The mind is described here as
a physical system with four functional dimensions that can be interre
lated mathematically on the basis of information theory. These variabl
es describe the information processing activities of the mind, and inc
lude: a) a state function (g), which is the number of potential states
that the system can occupy at a given time and relates to the complex
ity and activity of the brain; b) a power function (P), the number of
state changes per unit time; c) time (t); and d) the relative entropy
of the system (R), which describes the ordering of mental states in ti
me. Using these variables, the evolution of states of mind can be desc
ribed as a trajectory in a multidimensional phase space representing a
ll possible mental states. Ego functions constrain the field of brain
states within this space, thereby giving rise to the information conte
nt of consciousness and to the individual psyche. Functional mental di
sorders, as disorders of the psyche, are dysfunctions in the ordering
processes that give rise to conscious information.