title: Parcellation of Human and Monkey Core Auditory Cortex with fMRI Pattern Classification and Objective Detection of Tonotopic Gradient Reversals.
abstract: Auditory cortex (AC) contains several primary-like, or "core," fields, which receive thalamic input and project to non-primary "belt" fields. In humans, the organization and layout of core and belt auditory fields are still poorly understood, and most auditory neuroimaging studies rely on macroanatomical criteria, rather than functional localization of distinct fields. A myeloarchitectonic method has been suggested recently for distinguishing between core and belt fields in humans (Dick F, Tierney AT, Lutti A, Josephs O, Sereno MI, Weiskopf N. 2012. In vivo functional and myeloarchitectonic mapping of human primary auditory areas. J Neurosci. 32:16095-16105). We propose a marker for core AC based directly on functional magnetic resonance imaging (fMRI) data and pattern classification. We show that a portion of AC in Heschl's gyrus classifies sound frequency more accurately than other regions in AC. Using fMRI data from macaques, we validate that the region where frequency classification performance is significantly above chance overlaps core auditory fields, predominantly A1. Within this region, we measure tonotopic gradients and estimate the locations of the human homologues of the core auditory subfields A1 and R. Our results provide a functional rather than anatomical localizer for core AC. We posit that inter-individual variability in the layout of core AC might explain disagreements between results from previous neuroimaging and cytological studies.
authors.affiliation: Laboratory for Brain, Music and Sound Research (BRAMS), Montreal, Canada Department of Psychology, University of Montreal, Montreal, Canada Montreal Neurological Institute, McGill University, Montreal, Canada.
authors.forename: Marc
authors.initials: M
authors.lastname: Schönwiesner
authors.affiliation: Department of Cognitive Neurology, MR-Research in Neurology and Psychiatry, University Medicine Göttingen, Göttingen, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Dechent
authors.affiliation: Biomedical NMR Research GmbH, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Voit
authors.affiliation: Institute of Neuroscience, Newcastle University Medical School, Newcastle upon Tyne, UK.
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Petkov
authors.affiliation: MRC Institute of Hearing Research, Nottingham, UK.
authors.forename: Katrin
authors.initials: K
authors.lastname: Krumbholz
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008251:Macaca; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D012815:Signal Processing, Computer-Assisted; D013045:Species Specificity
keywords: hearing; tonotopy