title: Speech-specific tuning of neurons in human superior temporal gyrus.
abstract: How the brain extracts words from auditory signals is an unanswered question. We recorded approximately 150 single and multi-units from the left anterior superior temporal gyrus of a patient during multiple auditory experiments. Against low background activity, 45% of units robustly fired to particular spoken words with little or no response to pure tones, noise-vocoded speech, or environmental sounds. Many units were tuned to complex but specific sets of phonemes, which were influenced by local context but invariant to speaker, and suppressed during self-produced speech. The firing of several units to specific visual letters was correlated with their response to the corresponding auditory phonemes, providing the first direct neural evidence for phonological recoding during reading. Maximal decoding of individual phonemes and words identities was attained using firing rates from approximately 5 neurons within 200 ms after word onset. Thus, neurons in human superior temporal gyrus use sparse spatially organized population encoding of complex acoustic-phonetic features to help recognize auditory and visual words.
authors.affiliation: Medical Engineering and Medical Physics, Department of Neurology.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Chan
authors.affiliation: Program in Speech and Hearing Bioscience and Technology, Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA, Department of Neurology.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Dykstra
authors.affiliation: Department of Neuroscience, Harvard University, Cambridge, MA, USA.
authors.forename: Vinay
authors.initials: V
authors.lastname: Jayaram
authors.affiliation: Multimodal Imaging Laboratory.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Leonard
authors.affiliation: Multimodal Imaging Laboratory.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Travis
authors.affiliation: National Institute for Health Research, Nottingham Hearing Biomedical Research Unit, Nottingham, UK and.
authors.forename: Brian
authors.initials: B
authors.lastname: Gygi
authors.affiliation: Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA.
authors.forename: Janet M
authors.initials: JM
authors.lastname: Baker
authors.affiliation: Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Emad
authors.initials: E
authors.lastname: Eskandar
authors.affiliation: Department of Neurology.
authors.forename: Leigh R
authors.initials: LR
authors.lastname: Hochberg
authors.affiliation: Multimodal Imaging Laboratory, Department of Radiology and Neurosciences, University of California, San Diego, La Jolla, CA, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Halgren
authors.affiliation: Department of Neurology.
authors.forename: Sydney S
authors.initials: SS
authors.lastname: Cash
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D006801:Humans; D008297:Male; D009474:Neurons / Q000502:physiology*; D010700:Phonetics; D013067:Speech Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology*
keywords: audition; human single units; microelectrodes; speech perception; superior temporal gyrus