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|Title:||ANTERIOR PARIETAL LOBE: GROSS MORPHOLOGY AND SULCAL PATTERNS|
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|Authors/Affiliations:||1 Veronika Zlatkina*; 1 Michael Petrides; |
1 Montreal Neurological Institute, McGill University, QC, Canada
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|Content:||Objectives: It is well-established that the post-central gyrus (PoCG), which lies between the central (CS) and the post-central (PoCS) sulci, is involved in somatosensory processing. As illustrated by the well-known homunculus based on the work of Penfield and colleagues, different body parts have different proportional representations on the PoCG. Although the PoCG can be reliably identified in the majority of brains, there has been little attempt to study the details of its gross morphology. The purpose of this study is to describe several important morphological features of the PoCG and the PoCS that defines its caudal border which are often observed on the human brain. The purpose of this study is to provide reliable morphological information so that the various features of the PoCG and PoCS can be related to the somatosensory representation in the human brain. |
Materials and Methods: We examined twenty-five high-resolution T1-weighted magnetic resonance imaging (MRI) brain scans of healthy right-handed volunteers from the International Consortium for Brain Mapping database. All MRI brain volumes were transformed into the MNI standard proportional stereotaxic space. An interactive 3D imaging software was used to view the scans simultaneously in the coronal, horizontal and sagittal planes of section. Morphological features of interest, such as the sulci, were marked in all planes using a brush tool, which allowed us to determine their patterns and continuity.
Results: In the majority of brains studied, superficial folds were observed in comparable locations along the dorso-ventral extent of the PoCG. Sulci in the ventral part of the PoCG either remained separate or merged with the Sylvian fissure. Frequently, the PoCS was continuous (uninterrupted), but in a number of cases it consisted of two clearly separate superior and inferior segments. These were separated by a narrow gyrus that was either submerged or could be seen on the surface of the brain. The dorsal end of the PoCS often had a V-shape. In some brains, the PoCS merged with the Sylvian fissure, while in others it was disconnected from it by a gyrus. In a number of brains small sulci were seen ventral to the PoCS, and they either remained independent or merged with the Sylvian fissure.
Conclusions: The results of the present examination of the morphological features of the PoCG and PoCS show that, despite significant morphological variability in the anterior parietal lobe, there are distinct and reliable patterns formed by the PoCS and small sulci within the PoCG. The location of these structures in standard proportional stereotaxic space will be described so that these patterns can be used to relate activation foci from functional neuroimaging of the primary somatosensory cortex to the gross morphology of the rostral parietal lobe.
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