Poster E45, Monday, March 26, 2:30-4:30 pm, Exhibit Hall C
Spatio-temporal granularity of dorsal stream processing during word production
F.-Xavier Alario1, Catherine Liégeois-Chauvel2,3, Anne-Sophie Dubarry4, Irene Wang3, S Alomar3, Imad M. Najm3, Patrick Chauvel2,3, Jorge Gonzalez-Martinez3; 1Aix Marseille Univ, CNRS, LPC, Marseille, France, 2Aix Marseille Univ, INSERM, INS, Inst Neurosci Syst, Marseille, France, 3Cleveland Clinic Foundation, Cleveland (OH), USA, 4Aix Marseille Univ, CNRS, LPL, Aix-en-Provence, France
A left lateralized dorsal pathway is thought to map auditory-phonological information with articulatory motor programs during word production. The dorsal stream interfaces temporo-parietal areas with frontal areas, particularly supra-marginal gyrus, angular gyrus, etc. with inferior frontal gyrus. To quantify dorsal stream activity at a finer spatial and temporal granularity than is currently available, we used functional data recorded from intra-cerebral electrodes (implanted for pre-surgical diagnosis purposes) in epileptic patients performing picture naming task. For each electrode contact, we computed intra-cerebral event related potentials (iERP) and high gamma activity (HGA) as indexes of focal processing within the area. Significant activity was detected per contact, then combined across patients using a consistency criterion. The results revealed the involvement/activation of widespread network. Significant iERPs were detected in Supramarginal Gyrus and Angular Gyrus, peaking on average 320 ms after stimulus. Responses in Angular Gyrus were much more consistent across patients than in Supramarginal Gyrus. Significant iERPs and HGA were also detected in left IFG, peaking around 350 ms. They were most clear and consistent in Pars opercularis, compared to Triangularis and Orbitalis. In conclusion, dorsal stream activity during word production simultaneously involves specific sub-regions within temporo-parietal and inferior frontal areas.
Topic Area: LANGUAGE: Lexicon