Statistical analysis of hippocampal asymmetry in schizophrenia

The asymmetry of brain structures has been studied in schizophrenia to bett er understand its underlying neurobiology. Brain regions of interest have p reviously been characterized by volumes, cross-sectional and surface areas, and lengths. Using high-dimensional brain mapping, we have developed a sta tistical method for analyzing patterns of left-right asymmetry of the human hippocampus taken from high-resolution MR scans. We introduce asymmetry me asures that capture differences in the patterns of high-dimensional vector fields between the left and right hippocampus surfaces. In 15 pairs of subj ects previously studied (J. G. Csernansky et al., 1998, Proc. Natl. Acad. S ci. USA 95, 11406-11411). we define the difference in hippocampal asymmetry patterns between the groups. Volume analysis indicated a large normative a symmetry between left and right hippocampus (R > L), and shape analysis all owed us to visualize the normative asymmetry pattern of the hippocampal sur faces. We observed that the right hippocampus was wider along its lateral s ide in both schizophrenia and control subjects. Also, while patterns of hip pocampal asymmetry were generally similar in the schizophrenia and control groups, a principal component analysis based on left-right asymmetry vector fields detected a statistically significant difference between the two gro ups, specifically related to the subiculum. (C) 2001 Academic Press.