title: Processing of natural sounds: characterization of multipeak spectral tuning in human auditory cortex.
abstract: We examine the mechanisms by which the human auditory cortex processes the frequency content of natural sounds. Through mathematical modeling of ultra-high field (7 T) functional magnetic resonance imaging responses to natural sounds, we derive frequency-tuning curves of cortical neuronal populations. With a data-driven analysis, we divide the auditory cortex into five spatially distributed clusters, each characterized by a spectral tuning profile. Beyond neuronal populations with simple single-peaked spectral tuning (grouped into two clusters), we observe that ∼60% of auditory populations are sensitive to multiple frequency bands. Specifically, we observe sensitivity to multiple frequency bands (1) at exactly one octave distance from each other, (2) at multiple harmonically related frequency intervals, and (3) with no apparent relationship to each other. We propose that beyond the well known cortical tonotopic organization, multipeaked spectral tuning amplifies selected combinations of frequency bands. Such selective amplification might serve to detect behaviorally relevant and complex sound features, aid in segregating auditory scenes, and explain prominent perceptual phenomena such as octave invariance.
authors.affiliation: Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, 6200 MD Maastricht, The Netherlands. michelle.moerel@maastrichtuniversity.nl
authors.forename: Michelle
authors.initials: M
authors.lastname: Moerel
authors.forename: Federico
authors.initials: F
authors.lastname: De Martino
authors.forename: Roberta
authors.initials: R
authors.lastname: Santoro
authors.forename: Kamil
authors.initials: K
authors.lastname: Ugurbil
authors.forename: Rainer
authors.initials: R
authors.lastname: Goebel
authors.forename: Essa
authors.initials: E
authors.lastname: Yacoub
authors.forename: Elia
authors.initials: E
authors.lastname: Formisano
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009474:Neurons / Q000502:physiology; D013016:Sound; D013017:Sound Localization / Q000502:physiology