title: Evidence for excessive frontal evoked gamma oscillatory activity in schizophrenia during working memory.
abstract: Gamma (gamma) oscillations (30-50 Hz) elicited during working memory (WM) are altered in schizophrenia (SCZ). However, the nature of the relationship between evoked frontal oscillatory activity, WM performance and symptom severity has yet to be ascertained. This study had two objectives. First, to extend previous studies by examining delta, theta, alpha, beta, and gamma (delta, theta, alpha, beta, and gamma) oscillatory activities during the N-back task in SCZ patients compared to healthy subjects; second, to evaluate the relationship between oscillatory activities elicited during the N-back, performance, and clinical symptoms in SCZ patients. Patients with SCZ elicited excessive frontal gamma oscillatory activity that was most pronounced in the 3-back condition compared to healthy subjects. Reduced frontal beta activity at all WM loads was also observed in patients with SCZ compared to healthy subjects. Task performance was inversely correlated with negative symptoms but not with positive symptoms. Our findings suggest that evoked frontal oscillatory activities during WM are selectively altered in the gamma and beta frequency bands that may contribute to WM impairment in SCZ patients. These findings may provide important insights into the pathophysiology underlying WM deficits, its relationship to negative symptoms and may represent a potential neurobiological marker for cognitive enhancing strategies in SCZ.
authors.affiliation: Schizophrenia Program, Centre for Addiction and Mental Health, Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: M S
authors.initials: MS
authors.lastname: Barr
authors.forename: F
authors.initials: F
authors.lastname: Farzan
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Tran
authors.forename: R
authors.initials: R
authors.lastname: Chen
authors.forename: P B
authors.initials: PB
authors.lastname: Fitzgerald
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Daskalakis
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D001931:Brain Mapping; D004569:Electroencephalography / Q000379:methods; D005260:Female; D005625:Frontal Lobe / Q000187:drug effects / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000209:etiology* / Q000473:pathology*; D008570:Memory, Short-Term / Q000187:drug effects / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012559:Schizophrenia / Q000150:complications* / Q000188:drug therapy; D012565:Schizophrenic Psychology; D013057:Spectrum Analysis; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents