[The frontal lobe and psychoses]

Manic-depressive illness may be explained as an alteration of the normally existing equilibrium to be found between two antagonist brain mechanisms located in the prefrontal isocortex area. Each mechanism, located in the middle frontal area, deriving from the hippocampal allocortex, is responsible for tendencies to change. Its predominance leads to clinical patterns of mania. The other mechanism--located in the lateral orbital area, deriving from the olfactory allocortex, is responsible for tendencies to perseveration. Its predominance leads to clinical patterns of depression. Any alteration in the frontal lobe morphogenesis is likely to cause a permanent unbalance between both mechanisms. Consequently, an oscillation between opposite tendencies--i.e. a tendency to change, and a tendency to perseveration, may be expected which, clinically speaking, appears as mania, and depression phases. In this connection, the following points are discussed, namely (a) prefrontal functions, (b) peri-allocortex frontal zones participating in affective behaviors, (c) the problem of differences between brain hemispheres, and the probability of an anatomic basis for temperament. Eventually, features of a psychiatric science based on brain anatomy are enhanced.