Hemispheric asymmetries in cortical and subcortical anatomy

Xiaojian Kangab*, Timothy J. Herrona, Marc Ettlingera & David L. Woodsabca Human Cognitive Neurophysiology Lab, VA Research Service 151, VA-NCHCS, Martinez, CA, USA b Department of Neurology and Center for Neuroscience, UC Davis, Sacramento, CA, USA c UC Davis Center for Mind and Brain, UC Davis, Davis, CA, USA Address correspondence to: Xiaojian Kang, Department of Neurology and Neurosciences Center, UC Davis, VANCHCS, Research Services (151), 150 Muir Road, Martinez, CA 94553, USA. E-mail: xkang@ucdavis.eduThe content is solely the responsibility of the authors and does not necessarily represent the official views of Department of Veterans Affairs or the U.S. Government.No potential conflict of interest was reported by the authors.This research was supported by a VA Merit Research [grant number CX000583], [grant number CX001000] to DLW.Xiaojian Kang and Timothy J. Herron contributed equally to this work.Previous research studies have reported many hemispherical asymmetries in cortical and subcortical anatomy, but only a subset of findings is consistent across studies. Here, we used improved Freesurfer-based automated methods to analyse the properties of the cortex and seven subcortical structures in 138 young adult subjects. Male and female subjects showed similar hemispheric asymmetries in gyral and sulcal structures, with many areas associated with language processing enlarged in the left hemisphere (LH) and a number of areas associated with visuospatial processing enlarged in the right hemisphere (RH). In addition, we found greater (non-directional) cortical asymmetries in subjects with larger brains. Asymmetries in subcortical structures included larger LH volumes of thalamus, putamen and globus pallidus and larger RH volumes of the cerebellum and the amygdala. We also found significant correlations between the subcortical structural volumes, particularly of the thalamus and cerebellum, with cortical area. These results help to resolve some of the inconsistencies in previous studies of hemispheric asymmetries in brain anatomy.