Journal Article

New insights into the anatomo-functional connectivity of the semantic system: a study using cortico-subcortical electrostimulations

Hugues Duffau, Peggy Gatignol, Emmanuel Mandonnet, Philippe Peruzzi, Nathalie Tzourio-Mazoyer and Laurent Capelle

in Brain

Published on behalf of The Guarantors of Brain

Volume 128, issue 4, pages 797-810
Published in print April 2005 | ISSN: 0006-8950
Published online February 2005 | e-ISSN: 1460-2156 | DOI: http://dx.doi.org/10.1093/brain/awh423
New insights into the anatomo-functional connectivity of the semantic system: a study using cortico-subcortical electrostimulations

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Despite a better understanding of the organization of the cortical network underlying the semantic system, very few data are currently available regarding its anatomo-functional connectivity. Here, we report on a series of 17 patients operated on under local anaesthesia for a cerebral low-grade glioma located within the dominant hemisphere. Prior to and during resection, intraoperative electrical stimulation was used to map sensorimotor and language structures so that permanent neurological deficits could be avoided. In a number of cases, cortical and subcortical stimulation caused semantic paraphasias. Using postoperative MRI, we correlated these functional findings with the anatomical locations of the sites where semantic errors were elicited by stimulation, especially at the subcortical level, with the aim of studying the connectivity underlying the semantic system. In temporal gliomas, cortical sites involved in semantic processing were found around the posterior part of the superior temporal sulcus, with subcortical pathways reproducibly located under the depth of this sulcus. In insular gliomas, although stimulation elicited no semantic disturbances at the cortical level, such semantic paraphasias were generated at the level of the anterior floor of the external capsule. In frontal tumours, cortical regions implicated in semantics were detected in the lateral orbitofrontal region and dorsolateral prefrontal cortex, with subcortical fibres located under the inferior frontal sulcus. All these eloquent structures were systematically preserved, thereby avoiding permanent postoperative deficits. Our results provide arguments in favour of the existence of a main ventral subcortical pathway underlying the semantic system, within the dominant hemisphere, joining the two essential cortical epicentres of this network: the posterior and superior temporal areas, and the orbitofrontal and dorsolateral prefontal regions. Such a ventral stream might anatomically partly correspond to the inferior fronto-occipital fasciculus.

Keywords: semantic; connectivity; language; electrical stimulation; glioma surgery; BA = Brodmann area; BDAE = Boston Diagnostic Aphasia Examination; DTI = diffusion tensor imaging; DLPFC = dorsolateral prefrontal cortex; IFC = inferior frontal cortex

Journal Article.  10276 words.  Illustrated.

Subjects: Neurology ; Neuroscience

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