Since its first characterization in the 1920s, much attention has focused on the possibility of an underlying Grundstörung (common functional disturbance) in Gerstmann’s syndrome due to its diversity in symptomology amongst unique cognitive domains. This makes pure Gerstmann’s syndrome rare and very difficult to study. However, there is much debate regarding the exact location of a cortical lesion within the parietal lobe which can lead to such diverse clinical symptoms. 1, 2 It is generally agreed to occur with damage to the dominant parietal lobe, often following cerebral infarction. Gerstmann’s syndrome is a constellation of severe neurological deficits, namely agraphia, acalculia, finger agnosia, and left–right discrimination. These results provide clinically actionable and precise anatomic information which may help guide clinical translation in this region, such as during resective brain surgery in or near the intraparietal sulcus, and provides an empiric basis for future study. We identified a ‘Gerstmann Core’ of extensively connected functional regions where at least three of the four networks overlap. We present a tractographic model of the four neural networks involved in the functions which are impaired in Gerstmann syndrome. These regions were extensively connected in the intraparietal sulcus, as well as with a number of surrounding large-scale brain networks involved in higher-order functions. Area 7PC was found to be involved in all four domains. These parcels surround the anteromedial portion of the intraparietal sulcus. There were three parcels in the left hemisphere, where the ALE of at least three cognitive domains were found to be overlapping, specifically the anterior intraparietal area, area 7 postcentral (7PC) and the medial intraparietal sulcus. A frontoparietal network was found to be involved in the four cognitive domains: calculation, writing, finger gnosis, and left–right orientation. Ultimately 102 functional MRI studies met our inclusion criteria. Diffusion spectrum imaging-based tractography was performed to determine the structural connectivity between relevant parcels in each domain on 51 healthy subjects from the HCP database. Machine-learning was used to match activated regions of the ALE to the corresponding parcel from the cortical parcellation scheme previously published under the Human Connectome Project (HCP). Coordinate-based, meta-analytic software was utilized to gather relevant regions of interest from included studies to create an activation likelihood estimation (ALE) map for each cognitive domain. A literature search was conducted for healthy task-based functional MRI and PET studies for the four cognitive domains underlying Gerstmann’s tetrad using the electronic databases PubMed, Medline, and BrainMap Sleuth (2.4). Advancements in data-driven, computational modelling provides an opportunity to create a unified cortical model with greater anatomic precision based on underlying structural and functional connectivity across complex cognitive domains. Despite a growing interest in this clinical phenomenon, there remains controversy regarding the specific neuroanatomic substrates involved. The Gerstmann syndrome is a constellation of neurological deficits that include agraphia, acalculia, left–right discrimination and finger agnosia.
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