title: Medial frontal white and gray matter contributions to general intelligence.
abstract: The medial orbitofrontal cortex (mOFC) and rostral anterior cingulate cortex (rACC) are part of a wider neural network that plays an important role in general intelligence and executive function. We used structural brain imaging to quantify magnetic resonance gray matter volume and diffusion tensor white matter integrity of the mOFC-rACC network in 26 healthy participants who also completed neuropsychological tests of intellectual abilities and executive function. Stochastic tractography, the most effective Diffusion Tensor Imaging method for examining white matter connections between adjacent gray matter regions, was employed to assess the integrity of mOFC-rACC pathways. Fractional anisotropy (FA), which reflects the integrity of white matter connections, was calculated. Results indicated that higher intelligence correlated with greater gray matter volumes for both mOFC and rACC, as well as with increased FA for left posterior mOFC-rACC connectivity. Hierarchical regression analyses revealed that DTI-derived FA of left posterior mOFC-rACC uniquely accounted for 29%-34% of the variance in IQ, in comparison to 11%-16% uniquely explained by gray matter volume of the left rACC. Together, left rACC gray matter volume and white matter connectivity between left posterior mOFC and rACC accounted for up to 50% of the variance in general intelligence. This study is to our knowledge the first to examine white matter connectivity between OFC and ACC, two gray matter regions of interests that are very close in physical proximity, and underscores the important independent contributions of variations in rACC gray matter volume and mOFC-rACC white matter connectivity to individual differences in general intelligence.
authors.affiliation: Psychiatry Neuroimaging Laboratory, Department of Psychiatry and Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States of America; Clinical Neuroscience Division, Laboratory of Neuroscience, Department of Psychiatry, Veterans Affairs (VA) Boston Healthcare System, Harvard Medical School Brockton, MA, United States of America.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ohtani
authors.affiliation: Clinical Neuroscience Division, Laboratory of Neuroscience, Department of Psychiatry, Veterans Affairs (VA) Boston Healthcare System, Harvard Medical School Brockton, MA, United States of America; Department of Psychology, University of Massachusetts, Boston, MA, United States of America.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Nestor
authors.affiliation: Psychiatry Neuroimaging Laboratory, Department of Psychiatry and Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States of America.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bouix
authors.affiliation: Psychiatry Neuroimaging Laboratory, Department of Psychiatry and Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States of America.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Saito
authors.affiliation: Psychiatry Neuroimaging Laboratory, Department of Psychiatry and Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States of America; Clinical Neuroscience Division, Laboratory of Neuroscience, Department of Psychiatry, Veterans Affairs (VA) Boston Healthcare System, Harvard Medical School Brockton, MA, United States of America.
authors.forename: Taiga
authors.initials: T
authors.lastname: Hosokawa
authors.affiliation: Psychiatry Neuroimaging Laboratory, Department of Psychiatry and Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States of America.
authors.forename: Marek
authors.initials: M
authors.lastname: Kubicki
mesh_terms: D000328:Adult; D016880:Anisotropy; D003071:Cognition; D056324:Diffusion Tensor Imaging; D066128:Gray Matter / Q000033:anatomy & histology / Q000502:physiology*; D006179:Gyrus Cinguli / Q000033:anatomy & histology*; D006801:Humans; D007360:Intelligence; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D009483:Neuropsychological Tests; D009929:Organ Size; D017397:Prefrontal Cortex / Q000033:anatomy & histology*; D066127:White Matter / Q000033:anatomy & histology / Q000502:physiology*