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

H. Duffau
Brain. 2005-02-02; 128(4): 797-810
DOI: 10.1093/brain/awh423

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1. Brain. 2005 Apr;128(Pt 4):797-810. Epub 2005 Feb 10.

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

Duffau H(1), Gatignol P, Mandonnet E, Peruzzi P, Tzourio-Mazoyer N, Capelle L.

Author information:
(1)Department of Neurosurgery, U 678, Hôpital Salpêtrière, 47-83 Bd de l’Hôpital,
75651 Paris, Cedex 13, France.

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.

DOI: 10.1093/brain/awh423
PMID: 15705610 [Indexed for MEDLINE]

Auteurs Bordeaux Neurocampus