title: Discrimination of timbre in early auditory responses of the human brain.
abstract: BACKGROUND
  The issue of how differences in timbre are represented in the neural response still has not been well addressed, particularly with regard to the relevant brain mechanisms. Here we employ phasing and clipping of tones to produce auditory stimuli differing to describe the multidimensional nature of timbre. We investigated the auditory response and sensory gating as well, using by magnetoencephalography (MEG).
  
  
  RESULTS
  Thirty-five healthy subjects without hearing deficit participated in the experiments. Two different or same tones in timbre were presented through conditioning (S1)-testing (S2) paradigm as a pair with an interval of 500 ms. As a result, the magnitudes of auditory M50 and M100 responses were different with timbre in both hemispheres. This result might support that timbre, at least by phasing and clipping, is discriminated in the auditory early processing. The second response in a pair affected by S1 in the consecutive stimuli occurred in M100 of the left hemisphere, whereas both M50 and M100 responses to S2 only in the right hemisphere reflected whether two stimuli in a pair were the same or not. Both M50 and M100 magnitudes were different with the presenting order (S1 vs. S2) for both same and different conditions in the both hemispheres.
  
  
  CONCLUSIONS
  Our results demonstrate that the auditory response depends on timbre characteristics. Moreover, it was revealed that the auditory sensory gating is determined not by the stimulus that directly evokes the response, but rather by whether or not the two stimuli are identical in timbre.
authors.affiliation: Interdisciplinary Program in Cognitive Science, Seoul National University College of Humanities, Seoul, Korea.
authors.forename: Jaeho
authors.initials: J
authors.lastname: Seol
authors.forename: MiAe
authors.initials: M
authors.lastname: Oh
authors.forename: June Sic
authors.initials: JS
authors.lastname: Kim
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Jin
authors.forename: Sun Il
authors.initials: SI
authors.lastname: Kim
authors.forename: Chun Kee
authors.initials: CK
authors.lastname: Chung
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001921:Brain / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D010897:Pitch Discrimination; D055139:Sensory Gating / Q000502:physiology*