title: Mapping the connectivity underlying multimodal (verbal and non-verbal) semantic processing: a brain electrostimulation study.
abstract: Accessing the meaning of words, objects, people and facts is a human ability, made possible thanks to semantic processing. Although studies concerning its cortical organization are proficient, the subcortical connectivity underlying this semantic network received less attention. We used intraoperative direct electrostimulation, which mimics a transient virtual lesion during brain surgery for glioma in eight awaken patients, to map the anatomical white matter substrate subserving the semantic system. Patients performed a picture naming task and a non-verbal semantic association test during the electrical mapping. Direct electrostimulation of the inferior fronto-occipital fascicle, a poorly known ventral association pathway which runs throughout the brain, induced in all cases semantic disturbances. These transient disorders were highly reproducible, and concerned verbal as well as non-verbal output. Our results highlight for the first time the essential role of the left inferior fronto-occipital fascicle in multimodal (and not only in verbal) semantic processing. On the basis of these original findings, and in the lights of phylogenetic considerations regarding this fascicle, we suggest its possible implication in the monitoring of the human level of consciousness related to semantic memory, namely noetic consciousness.
authors.affiliation: National Institute for Health and Medical Research (INSERM), U1051, Plasticity of the Central Nervous System, Human Stem Cells and Glial Tumors, Institute for Neurosciences of Montpellier, Montpellier University Medical Center, 80 Av Augustin Fliche, 34091 Montpellier, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Moritz-Gasser
authors.forename: Guillaume
authors.initials: G
authors.lastname: Herbet
authors.forename: Hugues
authors.initials: H
authors.lastname: Duffau
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology / Q000502:physiology*; D001931:Brain Mapping; D001932:Brain Neoplasms / Q000473:pathology / Q000601:surgery; D004558:Electric Stimulation; D005260:Female; D005910:Glioma / Q000473:pathology / Q000601:surgery; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000473:pathology / Q000502:physiology*; D012660:Semantics; D013997:Time Factors; D055815:Young Adult
keywords: Awake surgery; Connectivity; Direct electrical stimulation; Inferior fronto-occipital fascicle; Multimodality; Semantic processing