title: Semantic attributes are encoded in human electrocorticographic signals during visual object recognition.
abstract: Non-invasive neuroimaging studies have shown that semantic category and attribute information are encoded in neural population activity. Electrocorticography (ECoG) offers several advantages over non-invasive approaches, but the degree to which semantic attribute information is encoded in ECoG responses is not known. We recorded ECoG while patients named objects from 12 semantic categories and then trained high-dimensional encoding models to map semantic attributes to spectral-temporal features of the task-related neural responses. Using these semantic attribute encoding models, untrained objects were decoded with accuracies comparable to whole-brain functional Magnetic Resonance Imaging (fMRI), and we observed that high-gamma activity (70-110Hz) at basal occipitotemporal electrodes was associated with specific semantic dimensions (manmade-animate, canonically large-small, and places-tools). Individual patient results were in close agreement with reports from other imaging modalities on the time course and functional organization of semantic processing along the ventral visual pathway during object recognition. The semantic attribute encoding model approach is critical for decoding objects absent from a training set, as well as for studying complex semantic encodings without artificially restricting stimuli to a small number of semantic categories.
authors.affiliation: Department of Biomedical Engineering, Johns Hopkins University, 720 Rutland Ave., Baltimore, MD 21205, USA.
authors.forename: Kyle
authors.initials: K
authors.lastname: Rupp
authors.affiliation: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Roos
authors.affiliation: Department of Biomedical Engineering, Johns Hopkins University, 720 Rutland Ave., Baltimore, MD 21205, USA.
authors.forename: Griffin
authors.initials: G
authors.lastname: Milsap
authors.affiliation: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723, USA.
authors.forename: Carlos
authors.initials: C
authors.lastname: Caceres
authors.affiliation: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Ratto
authors.affiliation: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Chevillet
authors.affiliation: Department of Neurology, Johns Hopkins University, 600 N. Wolfe St., Meyer 2-161, Baltimore, MD 21287, USA.
authors.forename: Nathan E
authors.initials: NE
authors.lastname: Crone
authors.affiliation: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723, USA. Electronic address: mikew@jhu.edu.
authors.forename: Michael
authors.initials: M
authors.lastname: Wolmetz
mesh_terms: D000328:Adult; D000465:Algorithms; D001931:Brain Mapping; D000069279:Drug Resistant Epilepsy / Q000503:physiopathology / Q000601:surgery; D000069280:Electrocorticography; D004566:Electrodes; D005260:Female; D065818:Gamma Rhythm / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008959:Models, Neurological; D009778:Occipital Lobe / Q000502:physiology; D021641:Recognition, Psychology / Q000502:physiology*; D012660:Semantics; D013702:Temporal Lobe / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*
keywords: Electrocorticography; Encoding models; High-gamma activity; Object recognition; Semantics