title: Abnormal resting-state cortical coupling in chronic tinnitus.
abstract: BACKGROUND
  Subjective tinnitus is characterized by an auditory phantom perception in the absence of any physical sound source. Consequently, in a quiet environment, tinnitus patients differ from control participants because they constantly perceive a sound whereas controls do not. We hypothesized that this difference is expressed by differential activation of distributed cortical networks.
  
  
  RESULTS
  The analysis was based on a sample of 41 participants: 21 patients with chronic tinnitus and 20 healthy control participants. To investigate the architecture of these networks, we used phase locking analysis in the 1-90 Hz frequency range of a minute of resting-state MEG recording. We found: 1) For tinnitus patients: A significant decrease of inter-areal coupling in the alpha (9-12 Hz) band and an increase of inter-areal coupling in the 48-54 Hz gamma frequency range relative to the control group. 2) For both groups: an inverse relationship (r = -.71) of the alpha and gamma network coupling. 3) A discrimination of 83% between the patient and the control group based on the alpha and gamma networks. 4) An effect of manifestation on the distribution of the gamma network: In patients with a tinnitus history of less than 4 years, the left temporal cortex was predominant in the gamma network whereas in patients with tinnitus duration of more than 4 years, the gamma network was more widely distributed including more frontal and parietal regions.
  
  
  CONCLUSIONS
  In the here presented data set we found strong support for an alteration of long-range coupling in tinnitus. Long-range coupling in the alpha frequency band was decreased for tinnitus patients while long-range gamma coupling was increased. These changes discriminate well between tinnitus and control participants. We propose a tinnitus model that integrates this finding in the current knowledge about tinnitus. Furthermore we discuss the impact of this finding to tinnitus therapies using Transcranial Magnetic Stimulation (TMS).
authors.affiliation: Department of Psychology, University of Konstanz, Konstanz, Germany. winfried.schlee@uni-konstanz.de
authors.forename: Winfried
authors.initials: W
authors.lastname: Schlee
authors.forename: Thomas
authors.initials: T
authors.lastname: Hartmann
authors.forename: Berthold
authors.initials: B
authors.lastname: Langguth
authors.forename: Nathan
authors.initials: N
authors.lastname: Weisz
mesh_terms: D000328:Adult; D000368:Aged; D000513:Alpha Rhythm; D002540:Cerebral Cortex / Q000503:physiopathology*; D002908:Chronic Disease; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009415:Nerve Net / Q000503:physiopathology; D013702:Temporal Lobe / Q000503:physiopathology; D014012:Tinnitus / Q000503:physiopathology* / Q000628:therapy; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult