title: High frequency gamma activity in the left hippocampus predicts visual object naming performance.
abstract: Access to an object's name requires the retrieval of an arbitrary association between it's identity and a word-label. The hippocampus is essential in retrieving arbitrary associations, and thus could be involved in retrieving the link between an object and its name. To test this hypothesis we recorded the iEEG signal from epileptic patients, directly implanted in the hippocampus, while they performed a picture naming task. High-frequency broadband gamma (50-150 Hz) responses were computed as an index of population-level spiking activity. Our results show, for the first time, single-trial hippocampal dynamics between visual confrontation and naming. Remarkably, the latency of the hippocampal response predicts naming latency, while inefficient hippocampal activation is associated with "tip-of-the-tongue" states (a failure to retrieve the name of a recognized object) suggesting that the hippocampus is an active component of the naming network and that its dynamics are closely related to efficient word production.
authors.affiliation: Aix-Marseille Université, CNRS, LPC UMR 7290, Marseille 13001, France. Electronic address: carlos-miguel.hamame@univ-amu.fr.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Hamamé
authors.affiliation: Aix-Marseille Université, CNRS, LPC UMR 7290, Marseille 13001, France.
authors.forename: F-Xavier
authors.initials: FX
authors.lastname: Alario
authors.affiliation: Aix-Marseille Université, CNRS, LPC UMR 7290, Marseille 13001, France; Aix-Marseille Université, Inserm, INS UMR_S 1106, Marseille 13005, France.
authors.forename: Anais
authors.initials: A
authors.lastname: Llorens
authors.affiliation: Aix-Marseille Université, Inserm, INS UMR_S 1106, Marseille 13005, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Liégeois-Chauvel
authors.affiliation: Aix-Marseille Université, Inserm, INS UMR_S 1106, Marseille 13005, France; APHM, Centre Hospitalier de la Timone, Marseille 13005, France.
authors.forename: Agnés
authors.initials: A
authors.lastname: Trébuchon-Da Fonseca
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D032882:Comprehension / Q000502:physiology*; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology / Q000523:psychology; D005260:Female; D065818:Gamma Rhythm / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D007802:Language; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D055815:Young Adult
keywords: Electrocorticogram (EcoG); High-frequency gamma activity; Hippocampus; Intracranial EEG (iEEG); Language production; Lexicon; Medial temporal lobe (MTL); Picture naming; Tip-of-the-tongue state; Ventral stream