Smaller corpus callosum subregions containing motor fibers in schizophrenia Vina M. Goghari a, * , Donna J. Lang b , Sean W. Flynn a , Alex L. MacKay b , William G. Honer a a Centre for Complex Disorders, Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada b Departments of Physics and Radiology, University of British Columbia, Vancouver, BC, Canada Received 17 January 2004; received in revised form 23 August 2004; accepted 31 August 2004 Available online 12 October 2004 Abstract Neuropsychological and neurophysiological studies provide evidence for abnormal interhemispheric communication in schizophrenia. These abnormalities may have a substrate in structural irregularities of the corpus callosum. This study investigated schizophrenia patients (n=27) and healthy comparison subjects (n =31). Global and regional measurements of the corpus callosum were acquired from one midsagittal SPGR slice. Eight subregions were approximately matched to fiber pathways from cortical regions. Overall effects of diagnosis [Wilks’ Lambda F(8,46)=2.45, p =0.03] and diagnosis by age interaction [Wilks’ Lambda F(8,46)=2.58, p =0.02] were found in a MANCOVA of the eight functionally specific subregions. Specifically, chronic schizophrenia was associated with a smaller rostral body [lower by 6.9%, F(1,53)=9.70, p =0.003] and anterior midbody [lower by 9.7%, F(1,53)=4.89, p =0.03] subregions. The rostral body and anterior midbody subregions of the corpus callosum primarily have premotor, supplementary motor, and motor cortical fibers transversing through them. Functional abnormalities of the associated cortical regions are reported in schizophrenia. These novel findings suggest that structural abnormalities of the corpus callosum exist in schizophrenia, with perhaps the motor-specific subregions affected more than others. Structural differences in the corpus callosum may be a substrate for interhemispheric functional dysconnectivity in schizophrenia. D 2004 Elsevier B.V. All rights reserved. Keywords: Corpus callosum; White matter; MRI; Schizophrenia; Motor fibers 1. Introduction Schizophrenia might be associated with impaired interhemispheric communication (Coger and Serafe- tinides, 1990). Structural differences in the corpus 0920-9964/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.schres.2004.08.023 * Corresponding author. Department of Psychology, University of Minnesota, N218 Elliott Hall, 75 East River Road, Minneapolis, MN 55455 United States. Tel.: +612 626 0698; fax: +612 625 6668. E-mail address: gogh0001@umn.edu (V.M. Goghari). Schizophrenia Research 73 (2005) 59 – 68 www.elsevier.com/locate/schres