title: Subjective loudness and reality of auditory verbal hallucinations and activation of the inner speech processing network.
abstract: BACKGROUND
  One of the most influential cognitive models of auditory verbal hallucinations (AVH) suggests that a failure to adequately monitor the production of one's own inner speech leads to verbal thought being misidentified as an alien voice. However, it is unclear whether this theory can explain the phenomenological complexity of AVH. We aimed to assess whether subjective perceptual and experiential characteristics may be linked to neural activation in the inner speech processing network.
  
  
  METHODS
  Twenty-two patients with schizophrenia and AVH underwent a 3-T functional magnetic resonance imaging scan, while performing a metrical stress evaluation task, which has been shown to activate both inner speech production and perception regions. Regions of interest (ROIs) comprising the putative inner speech network were defined using the Anatomical Automatic Labeling system. Correlations were calculated between scores on the "loudness" and "reality" subscales of the Auditory Hallucination Rating Scale (AHRS) and activation in these ROIs. Second, the AHRS subscales, and general AVH severity, indexed by the Positive and Negative Syndrome Scale, were correlated with a language lateralization index.
  
  
  RESULTS
  Louder AVH were associated with reduced task-related activity in bilateral angular gyrus, anterior cingulate gyrus, left inferior frontal gyrus, left insula, and left temporal cortex. This could potentially be due to a competition for shared neural resources. Reality on the other hand was found to be associated with reduced language lateralization.
  
  
  CONCLUSIONS
  Strong activation of the inner speech processing network may contribute to the subjective loudness of AVH. However, a relatively increased contribution from right hemisphere language areas may be responsible for the more complex experiential characteristics, such as the nonself source or how real AVH are.
authors.affiliation: Department of Neuroscience, University Medical Center Groningen, Groningen, The Netherlands. a.vercammen@med.umcg.nl
authors.forename: Ans
authors.initials: A
authors.lastname: Vercammen
authors.forename: Henderikus
authors.initials: H
authors.lastname: Knegtering
authors.forename: Richard
authors.initials: R
authors.lastname: Bruggeman
authors.forename: André
authors.initials: A
authors.lastname: Aleman
mesh_terms: D000293:Adolescent; D000328:Adult; D002540:Cerebral Cortex / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006212:Hallucinations / Q000503:physiopathology* / Q000523:psychology; D006801:Humans; D007802:Language; D008144:Loudness Perception / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology*; D009483:Neuropsychological Tests; D013060:Speech / Q000502:physiology*; D055815:Young Adult