title: Auditory M50 and M100 sensory gating deficits in bipolar disorder: a MEG study.
abstract: OBJECTIVE
  Auditory sensory gating deficits have been reported in subjects with bipolar disorder, but the hemispheric and neuronal origins of this deficit are not well understood. Moreover, gating of the auditory evoked components reflecting early attentive stage of information processing has not been investigated in bipolar disorder. The objectives of this study were to investigate the right and left hemispheric auditory sensory gating of the M50 (preattentive processing) and M100 (early attentive processing) in patients diagnosed with bipolar I disorder by utilizing magnetoencephalography (MEG).
  
  
  METHODS
  Whole-head MEG data were acquired during the standard paired-click paradigm in 20 bipolar I disorder patients and 20 healthy controls. The M50 and the M100 responses were investigated, and dipole source localizations were also investigated. Sensory gating were determined by measuring the strength of the M50 and the M100 response to the second click divided by that of the first click (S2/S1).
  
  
  RESULTS
  In every subject, M50 and M100 dipolar sources localized to the left and right posterior portion of superior temporal gyrus (STG). Bipolar I disorder patients showed bilateral gating deficits in M50 and M100. The bilateral M50 S2 source strengths were significantly higher in the bipolar I disorder group compared to the control group.
  
  
  CONCLUSIONS
  The sample size was relatively small. More studies with larger sample sizes are warranted. Bipolar subjects were taking a wide range of medications that could not be readily controlled for.
  
  
  CONCLUSIONS
  These findings suggest that bipolar I disorder patients have auditory gating deficits at both pre-attentive and early attentive levels, which might be related to STG structural abnormality.
authors.affiliation: Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China; Clinical Experimental Center, First Affiliated Hospital of Jinan University, Guangzhou 510630, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Yigang
authors.initials: Y
authors.lastname: Feng
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Jia
authors.forename: Wensheng
authors.initials: W
authors.lastname: Wang
authors.forename: Yanping
authors.initials: Y
authors.lastname: Xie
authors.forename: Yufang
authors.initials: Y
authors.lastname: Guan
authors.forename: Shuming
authors.initials: S
authors.lastname: Zhong
authors.forename: Dan
authors.initials: D
authors.lastname: Zhu
authors.forename: Li
authors.initials: L
authors.lastname: Huang
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology; D016022:Case-Control Studies; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging; D055139:Sensory Gating; D013702:Temporal Lobe / Q000503:physiopathology; D055815:Young Adult
keywords: Auditory sensory gating; Bipolar disorder; M100; M50; Magnetoencephalography; Superior temporal gyrus