The brain sciences and advances in imaging technology draw the psychopathologist into the search for neuroanatomical loci for the major symptoms and behavioral abnormalities of mental diseases. But the pathway from symptom and behavior to brain area is not as simple as it may first appear. This chapter calls attention to some of the methodological errors that threaten to subvert our efforts. Some of these errors result from prematurely leaping to brain localization from very complex behaviors. Others reflect flawed extrapolations from established brain-behavior relations to as yet unestablished relations. Although the focus is on schizophrenia, the principles apply to the investigation of any disease process.
Scientific methodology has advanced considerably since Gall inferred that the characteristic of acquisitiveness was linked to a particularly prominent bump on the heads of pickpockets. Witness the fact that although there are numerous contemporary reports of memory disturbances in schizophrenics, there have been (thankfully) no attempts to look for corresponding bumps. The crudeness of Gall's theory of phrenology, reflected in its failure to employ experimental methods (no control groups, no “blind”) and in his fallacious causal reasoning, had enormous influence on scientific receptivity to ideas about the relation between behavior and the brain in the early and middle nineteenth century. Perhaps as a backlash against the nonempirical origins of Gall's phrenological speculations, prevailing scientific sen timent spurned attempts to localize behaviors in specific brain areas and continued to endorse Flourens' notion that mental functions and behavior had no specific brain correlates.