Functional and anatomical brain imaging: impact on schizophrenia research

A group of related new technologies has made it possible to study the brain's regional changes in metabolism, blood flow, electrical activity, and neurochemistry. Positron emission tomography (PET) produces slice images of radioisotope density--brain metabolism or receptor concentration can be quantitated. Studies in schizophrenia have indicated relative metabolic underactivity of the frontal lobes of schizophrenics. Decreased activity in the basal ganglia, which can be reversed with neuroleptic treatment, is also seen in schizophrenia. PET studies are in the early stages; standard methodology for isotope selection, task during tracer uptake, and quantitative analysis is still developing. Cerebral blood flow studies have shown similar patterns in the cortical surface. The electroencephalogram provides a short time resolution approach which can assess attention and arousal, but lacks some of the anatomic exactness and depth capabilities of PET. Magnetic resonance imaging furnishes anatomical images of gray and white matter previously unavailable with x-ray computed tomography. Advances in methodology and clinical studies with imaging are making neuroanatomic theories of schizophrenia more directly testable than ever before.