Despite the evidence that ventricular hormones do not make their way out of the ventricle, the presence of large ventricles in many schizophrenic patients, and the ability of two-dimensional gels to provide a profile of peptides in the ventricle, not a single catheter has been placed into the ventricle of a schizophrenic patient to measure the peptides in the ventricle.... There is no animal model for this disease, the answer can only come from human studies.

The Fabric of Mind (1985)