Representations of Invariant Musical Categories Are Decodable by Pattern Analysis of Locally Distributed BOLD Responses in Superior Temporal and Intraparietal Sulci.
In categorical perception (CP), continuous physical signals are mapped to discrete perceptual bins: mental categories not found in the physical world. CP has been demonstrated across multiple sensory modalities and, in audition, for certain over-learned speech and musical sounds. The neural basis of auditory CP, however, remains ambiguous, including its robustness in nonspeech processes and the relative roles of left/right hemispheres; primary/nonprimary cortices; and ventral/dorsal perceptual processing streams. Here, highly trained musicians listened to 2-tone musical intervals, which they perceive categorically while undergoing functional magnetic resonance imaging. Multivariate pattern analyses were performed after grouping sounds by interval quality (determined by frequency ratio between tones) or pitch height (perceived noncategorically, frequency ratios remain constant). Distributed activity patterns in spheres of voxels were used to determine sound sample identities. For intervals, significant decoding accuracy was observed in the right superior temporal and left intraparietal sulci, with smaller peaks observed homologously in contralateral hemispheres. For pitch height, no significant decoding accuracy was observed, consistent with the non-CP of this dimension. These results suggest that similar mechanisms are operative for nonspeech categories as for speech; espouse roles for 2 segregated processing streams; and support hierarchical processing models for CP.
Cognitive Neuroscience Unit, Montréal Neurological Institute, McGill University, Montréal, Québec, Canada H3A 2B4 International Laboratory for Brain, Music and Sound Research, Montréal, Québec, Canada H3C 3J7.
Mike E
ME
Klein
Cognitive Neuroscience Unit, Montréal Neurological Institute, McGill University, Montréal, Québec, Canada H3A 2B4 International Laboratory for Brain, Music and Sound Research, Montréal, Québec, Canada H3C 3J7.
Robert J
RJ
Zatorre
D000161:Acoustic Stimulation / Q000379:methods; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D015331:Cohort Studies; D004192:Discrimination, Psychological / Q000502:physiology; D005260:Female; D006801:Humans; D007600:Judgment / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015999:Multivariate Analysis; D009146:Music; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D010296:Parietal Lobe / Q000502:physiology*; D011361:Professional Competence; D012815:Signal Processing, Computer-Assisted; D013702:Temporal Lobe / Q000502:physiology*
D010100:Oxygen
MVPA; auditory categories; categorical perception; intraparietal sulcus; superior temporal sulcus