title: Fractal Dimension Analysis of Subcortical Gray Matter Structures in Schizophrenia.
abstract: A failure of adaptive inference-misinterpreting available sensory information for appropriate perception and action-is at the heart of clinical manifestations of schizophrenia, implicating key subcortical structures in the brain including the hippocampus. We used high-resolution, three-dimensional (3D) fractal geometry analysis to study subtle and potentially biologically relevant structural alterations (in the geometry of protrusions, gyri and indentations, sulci) in subcortical gray matter (GM) in patients with schizophrenia relative to healthy individuals. In particular, we focus on utilizing Fractal Dimension (FD), a compact shape descriptor that can be computed using inputs with irregular (i.e., not necessarily smooth) surfaces in order to quantify complexity (of geometrical properties and configurations of structures across spatial scales) of subcortical GM in this disorder. Probabilistic (entropy-based) information FD was computed based on the box-counting approach for each of the seven subcortical structures, bilaterally, as well as the brainstem from high-resolution magnetic resonance (MR) images in chronic patients with schizophrenia (n = 19) and age-matched healthy controls (n = 19) (age ranges: patients, 22.7-54.3 and healthy controls, 24.9-51.6 years old). We found a significant reduction of FD in the left hippocampus (median: 2.1460, range: 2.07-2.18 vs. median: 2.1730, range: 2.15-2.23, p<0.001; Cohen's effect size, U3 = 0.8158 (95% Confidence Intervals, CIs: 0.6316, 1.0)), the right hippocampus (median: 2.1430, range: 2.05-2.19 vs. median: 2.1760, range: 2.12-2.21, p = 0.004; U3 = 0.8421 (CIs: 0.5263, 1)), as well as left thalamus (median: 2.4230, range: 2.40-2.44, p = 0.005; U3 = 0.7895 (CIs: 0.5789, 0.9473)) in schizophrenia patients, relative to healthy individuals. Our findings provide in-vivo quantitative evidence for reduced surface complexity of hippocampus, with reduced FD indicating a less complex, less regular GM surface detected in schizophrenia.
authors.affiliation: School of Information Science and Engineering, Central South University, Changsha 410083, China.|Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY 10032, United States of America.
authors.forename: Guihu
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY 10032, United States of America.|Sackler Institute for Psychobiology, Columbia University College of Physicians and Surgeons, New York, NY 10032, United States of America.|Division of Developmental Neuroscience, New York State Psychiatric Institute, New York, NY 10032, United States of America.
authors.forename: Kristina
authors.initials: K
authors.lastname: Denisova
authors.affiliation: Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY 10032, United States of America.|Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, United States of America.
authors.forename: Pejman
authors.initials: P
authors.lastname: Sehatpour
authors.affiliation: School of Information Science and Engineering, Central South University, Changsha 410083, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Long
authors.affiliation: School of Information Science and Engineering, Central South University, Changsha 410083, China.
authors.forename: Weihua
authors.initials: W
authors.lastname: Gui
authors.affiliation: College of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Qiao
authors.affiliation: Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY 10032, United States of America.|Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, United States of America.
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Javitt
authors.affiliation: Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY 10032, United States of America.
authors.forename: Zhishun
authors.initials: Z
authors.lastname: Wang