Human frontal cortex: An MRI-based parcellation method

The frontal lobe is not a single anatomical and functional brain region. Se veral lines of research have demonstrated that particular subregions within the frontal lobe are associated with specific motor and cognitive function s in the human being. Our main purpose is to develop a magnetic resonance i mage (MRI)-based parcellation method of the frontal lobe that permits us to explore plausible abnormalities in functionally relevant frontal subregion s in brain illnesses. We describe a procedure using MRI for subdividing the entire frontal cortex into 11 subregions: supplementary motor area (SMA), rostral anterior cingulate gyrus (r-ACiG), caudal anterior cingulate gyrus (c-ACiG), superior cingulate gyrus (SCiG), medial frontal cortex (MFC), str aight gyrus (SG;), orbitofrontal cortex (OFC), precentral gyrus (PCG), supe rior frontal gyrus (SFG), inferior frontal gyrus (IFG), and middle frontal gyrus (MFG;). Our method posits to conserve the topographic uniqueness of i ndividual brains and is based on our ability to visualize both the three-di mensional (3D) rendered brain and the three orthogonal planes simultaneousl y. The reliability study for gray matter volume and surface area of each su bregion was performed on a set of 10 MR scans by two raters. The intraclass R coefficients for gray matter volume of each subregion ranged between 0.8 6 and 0.99. We describe here a reproducible and reliable topography-based p arcellation method of the frontal lobe that will allow us to use new approa ches to understand the role of particular frontal cortical subregions in sc hizophrenia and other brain illnesses. (C) 1999 Academic Press.