IN-VIVO MORPHOMETRY OF THE INTRASULCAL GRAY-MATTER IN THE HUMAN CINGULATE, PARACINGULATE, AND SUPERIOR-ROSTRAL SULCI - HEMISPHERIC ASYMMETRIES, GENDER DIFFERENCES AND PROBABILITY MAPS

Volumes of the intrasulcal gray matter were measured in three cerebral sulci located on the medial wall of the human frontal lobe: cingulate sulcus (CS), paracingulate sulcus (PCS), and superior-rostral sulcus (SRS). The measurements were carried out on T-1-weighted 3-D high-reso lution magnetic-resonance (MR) images acquired in 105 young right-hand ed volunteers (42 female and 63 male). Before the measurement, the ima ges were transformed into a standardized stereotaxic space (Talairach and Tournoux [1988] Human Brain: 3-Dimensional Proportional System. An Approach to Cerebral Imaging. Stuttgart, New York: Georg Thieme Verla g), thus removing inter-individual differences in brain size. The intr asulcal gray matter was segmented in a semi-automatic manner. Signific ant gender differences were found in the volume of the CS (female > ma le) and the PCS (male > female). Hemispheric asymmetries were observed between the left and right volumes of the intrasulcal gray matter in the anterior (right > left) and posterior (left > right) segments of t he CS, as well as between the left and right volumes of the PCS (left > right). There was no interaction between the asymmetries and gender. In addition, significant positive correlations were found between the left and right gray-matter volumes in the anterior (r = 0.43) and pos terior (r = 0.66) segments of the CS, whereas significant negative cor relations were observed between the gray-matter volumes of the anterio r segment of the CS and those of the PCS (left hemisphere: r = -0.48; right hemisphere: r = -0.42). The observed hemispheric asymmetries in the CS and PCS gray-matter volumes are consistent with the proposed ro le of these structures in the integration of emotions with cognition ( CS) and in the control of speech/vocalization (PCS). The pattern of in ter-hemispheric correlations in the sulcal gray-matter points to an in creasing asynchrony in the foetal development of primary (CS), seconda ry (SRS), and tertiary (PCS) sulci, respectively. The presence of nega tive correlations between the two neighbouring sulci (CS and PCS) sugg ests that a process of compensation could underlie interactions betwee n adjacent primary and tertiary sulci. Besides the above volumetric an alysis, we also provide average (probability) maps of the three sulci; the use of such maps for the parcellation of the medial frontal lobe and localization of ''peaks'' obtained in blood-flow activation studie s is discussed. (C) 1996 Wiley-Liss, Inc.