title: The difference between uni- and bilateral auditory phantom percept.
abstract: OBJECTIVE
  Tinnitus can be considered an auditory phantom percept, in which patients hear an internal sound in the absence of any external sound source, mimicking tonal memory. Tinnitus however can be perceived exclusively uni- or bilaterally.
  
  
  METHODS
  The neurophysiological differences were investigated between unilateral and bilateral tinnitus using LORETA source localized resting state EEG recordings.
  
  
  RESULTS
  The difference between unilateral and bilateral tinnitus is reflected by high frequency activity (beta and gamma) in the superior prefrontal gurus, right parahippocampus, right angular gyrus and right auditory cortex. Unilateral tinnitus is characterized by contralateral beta2 in the superior prefrontal gyrus in comparison to bilateral tinnitus, but gamma in comparison to non-tinnitus subjects. Bilateral tinnitus has delta activity in the ventrolateral prefrontal cortex in comparison to unilateral tinnitus, and bilateral beta1 in comparison to non-tinnitus subjects. Bilateral tinnitus is also characterized by bilateral frontopolar beta1 activity.
  
  
  CONCLUSIONS
  Unilateral and bilateral tinnitus can be differentiated based on their resting state oscillation patterns: beta3 and gamma-band activity in the superior premotor cortex, parahippocampal area and angular gyrus seem to form the core of a spatial localization network involved in tinnitus.
  
  
  CONCLUSIONS
  These differences should be taken into account when evaluating functional neuroimaging data relating to tinnitus.
authors.affiliation: Brai(2)n, TRI & Department of Neurosurgery, University Hospital Antwerp, Belgium. Electronic address: sven.vanneste@ua.ac.be.
authors.forename: Sven
authors.initials: S
authors.lastname: Vanneste
authors.affiliation: Brai(2)n, TRI & Department of Neurosurgery, University Hospital Antwerp, Belgium.
authors.forename: Mark
authors.initials: M
authors.lastname: Plazier
authors.affiliation: Brai(2)n, TRI & Department of Neurosurgery, University Hospital Antwerp, Belgium.
authors.forename: Elsa
authors.initials: E
authors.lastname: van der Loo
authors.affiliation: Brai(2)n, TRI & ENT, University Hospital Antwerp, Belgium.
authors.forename: Paul
authors.initials: P
authors.lastname: Van de Heyning
authors.affiliation: Brai(2)n, TRI & Department of Neurosurgery, University Hospital Antwerp, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: De Ridder
mesh_terms: D000368:Aged; D000513:Alpha Rhythm; D001303:Auditory Cortex / Q000503:physiopathology; D001307:Auditory Perception / Q000502:physiology*; D001611:Beta Rhythm; D016208:Databases, Factual; D003700:Delta Rhythm; D004569:Electroencephalography; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D020534:Parahippocampal Gyrus / Q000503:physiopathology; D014012:Tinnitus / Q000503:physiopathology*