title: Contributions of spectral frequency analyses to the study of P50 ERP amplitude and suppression in bipolar disorder with or without a history of psychosis.
abstract: OBJECTIVE
  The present study investigated event-related brain potential (ERP) indices of auditory processing and sensory gating in bipolar disorder and subgroups of bipolar patients with or without a history of psychosis using the P50 dual-click procedure. Auditory-evoked activity in two discrete frequency bands also was explored to distinguish between sensory registration and selective attention deficits.
  
  
  METHODS
  Thirty-one individuals with bipolar disorder and 28 non-psychiatric controls were compared on ERP indices of auditory processing using a dual-click procedure. In addition to conventional P50 ERP peak-picking techniques, quantitative frequency analyses were applied to the ERP data to isolate stages of information processing associated with sensory registration (20-50 Hz; gamma band) and selective attention (0-20 Hz; low-frequency band).
  
  
  RESULTS
  Compared to the non-psychiatric control group, patients with bipolar disorder exhibited reduced S1 response magnitudes for the conventional P50 peak-picking and low-frequency response analyses. A bipolar subgroup effect suggested that the attenuated S1 magnitudes from the P50 peak-picking and low-frequency analyses were largely attributable to patients without a history of psychosis.
  
  
  CONCLUSIONS
  The analysis of distinct frequency bands of the auditory-evoked response elicited during the dual-click procedure allowed further specification of the nature of auditory sensory processing and gating deficits in bipolar disorder with or without a history of psychosis. The observed S1 effects in the low-frequency band suggest selective attention deficits in bipolar patients, especially those patients without a history of psychosis, which may reflect a diminished capacity to selectively attend to salient stimuli as opposed to impairments of inhibitory sensory processes.
authors.affiliation: Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Carroll
authors.forename: Paul D
authors.initials: PD
authors.lastname: Kieffaber
authors.forename: Jenifer L
authors.initials: JL
authors.lastname: Vohs
authors.forename: Brian F
authors.initials: BF
authors.lastname: O'Donnell
authors.forename: Anantha
authors.initials: A
authors.lastname: Shekhar
authors.forename: William P
authors.initials: WP
authors.lastname: Hetrick
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001714:Bipolar Disorder / Q000150:complications*; D001921:Brain / Q000503:physiopathology*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009433:Neural Inhibition / Q000502:physiology*; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000150:complications*; D011930:Reaction Time / Q000502:physiology; D055139:Sensory Gating / Q000502:physiology*; D055815:Young Adult