title: Auditory verbal hallucinations in schizophrenia correlate with P50 gating.
abstract: OBJECTIVE
  While auditory verbal hallucinations (AVHs) are a common symptom of schizophrenia, the underlying mechanisms behind these perceptual anomalies and their effects on auditory processing are not fully understood. Patients suffering from schizophrenia have been shown to exhibit impaired sensory gating of acoustic stimuli, evidenced by a failure to inhibit the auditory P50 scalp recorded middle latency evoked potential response to the second of two paired auditory "clicks" (S1-S2).
  
  
  METHODS
  Because abnormal activation of auditory pathways is associated with a general AVH trait of schizophrenia patients, this study correlated the hallucinatory trait subscale of the Psychotic Symptoms Ratings Scale (PSYRATS) scores of 16 actively hallucinating patients with their P50 responses to S1 and S2 as well as sensory gating indices. P50 gating in patients was also compared to twenty one healthy controls.
  
  
  RESULTS
  Control S1 amplitudes were significantly greater than those of patients. There was a negative correlation between PSYRATS scores and gating difference score as well as with S1 amplitude, and a positive correlation with gating ratio, indicating the global trait of hallucinating schizophrenia patients may be associated with deficiencies in the processing of auditory stimuli. No significant correlation was found when the same analysis was applied to a state-dependent hallucination ratings scale.
  
  
  CONCLUSIONS
  Results suggest the relationship between auditory hallucinations and auditory processing dysfunction measured by P50 response is more trait than state dependent in schizophrenia.
authors.affiliation: Department of Cellular and Molecular Medicine/Neuroscience, University of Ottawa, Canada. Dylan.m.smith@gmail.com
authors.forename: Dylan M
authors.initials: DM
authors.lastname: Smith
authors.forename: Bryan
authors.initials: B
authors.lastname: Grant
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Fisher
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Borracci
authors.forename: Alain
authors.initials: A
authors.lastname: Labelle
authors.forename: Verner J
authors.initials: VJ
authors.lastname: Knott
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000704:Analysis of Variance; D001306:Auditory Pathways / Q000503:physiopathology; D001931:Brain Mapping; D016022:Case-Control Studies; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006212:Hallucinations / Q000209:etiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D011930:Reaction Time; D012559:Schizophrenia / Q000150:complications*; D055139:Sensory Gating / Q000502:physiology*; D011795:Surveys and Questionnaires