title: The neural correlates of subjectively perceived and passively matched loudness perception in auditory phantom perception.
abstract: BACKGROUND
  A fundamental question in phantom perception is determining whether the brain creates a network that represents the sound intensity of the auditory phantom as measured by tinnitus matching (in dB), or whether the phantom perception is actually only a representation of the subjectively perceived loudness.
  
  
  METHODS
  In tinnitus patients, tinnitus loudness was tested in two ways, by a numeric rating scale for subjectively perceived loudness and a more objective tinnitus-matching test, albeit it is still a subjective measure.
  
  
  RESULTS
  Passively matched tinnitus does not correlate with subjective numeric rating scale, and has no electrophysiological correlates. Subjective loudness, in a whole-brain analysis, is correlated with activity in the left anterior insula (alpha), the rostral/dorsal anterior cingulate cortex (beta), and the left parahippocampus (gamma). A ROI analysis finds correlations with the auditory cortex (high beta and gamma) as well. The theta band links gamma band activity in the auditory cortex and parahippocampus via theta-gamma nesting.
  
  
  CONCLUSIONS
  Apparently the brain generates a network that represents subjectively perceived tinnitus loudness only, which is context dependent. The subjective loudness network consists of the anterior cingulate/insula, the parahippocampus, and the auditory cortex. The gamma band activity in the parahippocampus and the auditory cortex is functionally linked via theta-gamma nested lagged phase synchronization.
authors: Department of Surgical Sciences, Section of Neurosurgery, Dunedin School of Medicine, University of Otago Dunedin, New Zealand ; BRAI²N, Sint Augustinus Hospital Antwerp, Belgium.
authors: Dirk
authors: D
authors: De Ridder
authors: Vision and Brain Signal processing (ViBS) Research Group, GIPSA-Lab, CNRS, Grenoble University Grenoble, France.
authors: Marco
authors: M
authors: Congedo
authors: School of Behavioral and Brain Sciences, The University of Texas at Dallas Dallas, Texas.
authors: Sven
authors: S
authors: Vanneste
mesh_terms: D000328:Adult; D001307:Auditory Perception / Q000502:physiology; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008144:Loudness Perception / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D014012:Tinnitus / Q000503:physiopathology*
keywords: Context; gamma; intensity; loudness; nesting; parahippocampus; theta; tinnitus