THALAMIC ABNORMALITIES IN SCHIZOPHRENIA VISUALIZED THROUGH MAGNETIC-RESONANCE IMAGE AVERAGING

Schizophrenia is a complex illness characterized by multiple types of symptoms involving many aspects of cognition and emotion. Most efforts to identify its underlying neural substrates have focused on a strate gy that relates a single symptom to a single brain region. An alternat ive hypothesis, that the variety of symptoms could be explained by a l esion in midline neural circuits mediating attention and information p rocessing, is explored. Magnetic resonance images from patients and co ntrols were transformed with a ''bounding box'' to produce an ''averag e schizophrenic brain'' and an ''average normal brain.'' After image s ubtraction of the two averages, the areas of difference were displayed as an effect size map. Specific regional abnormalities were observed in the thalamus and adjacent white matter. An abnormality in the thala mus and related circuitry explains the diverse symptoms of schizophren ia parsimoniously because they could all result from a defect in filte ring or gating sensory input, which is one of the primary functions of the thalamus in the human brain.