Chunk #26 — DIMENSIONS OF PSYCHOPATHOLOGY IN NEUROLEPTIC-NAÏVE PATIENTS WITH RECENT-ONSET SCHIZOPHRENIA — A proposal for MRI-based parcellation of the frontal pole
We proposed the coronal section containing the anterior termination of the olfactory sulcus (ATOS) as a cytoarchitectonically meaningful and a potentially functionally valid landmark for demarcating the posterior boundary of the FP on MR images [Figure 4]. Manual segmentation-based parcellation of the FP using the proposed landmark in 20 healthy volunteers yielded highly reliable (standardized item alpha = 0.92) volumetric estimates [right FP volume = 8.421 cm3 (S.E.=0.773; range: 3.107-15.741); left FP volume = 8.039 cm3 (S.E. = 0.708; range: 2.234-12.956)]. The volumetric measurements of right FP generated in the present study were comparable to those reported in a prior study of BA 10 using histological sections and stereological techniques.[81] This landmark corresponds to +49 to +50 in the coronal/verticofrontal axis in the standard Co- Planar Stereotaxic Atlas of the Human Brain by Talairach and Tournoux.[82] Independent functional validation of this structural MRI-based definition was provided by Smith et al.,[83] who, using a task to functionally localize the rostrolateral PFC, reported predominant activation foci with posterior limit overlapping with the above-mentioned Talairach y co-ordinate. Therefore, in the absence of a
