Abnormal neural oscillation to speech sounds in bipolar disorder

  • MD Naoya Oribe, Kyushu University, Japan
  • PhD Toshiaki Onitsuka, Kyushu University, Japan
  • PhD Shogo Hirano, Kyushu University, Japan
  • PhD Yoji Hirano, Kyushu University, Japan
  • PhD Takefumi Ueno, Kyushu University, Japan
  • PhD Choji Obayashi, Kyushu University, Japan
  • PhD Hiroaki Kawasaki, Kyushu University, Japan
  • PhD Shigenobu Kanba, Kyushu University, Japan

Objectives :
The synchronous activity of neurons mediated by oscillations in the Gamma band has been hypothesized to play an important role in the integration of perceptual features. Disruption of this neural oscillation could lead to abnormalities in feature binding and associative learning. These abnormalities may underlie the symptoms of psychiatric disorders. Several studies reported abnormal neural oscillation measured by electroencephalography and magnetoencephalography (MEG) in schizophrenia. Bipolar disorder is a severe mental illness characterized with alternation in mood and associated with cognitive deficits and thought disorder. Abnormal neural oscillation may contribute to these disturbances of cognitive and affective integration. In this study, we investigated the evoked neural oscillation (eNO) to speech and non-speech sound in left hemisphere in patients with bipolar disorder and compared them with those of patients with schizophrenia and normal controls using MEG.
Method :
11 Patients with bipolar disorder (BP), 12 patients with Schizophrenia (SZ) and 15 normal control subjects (NC) participated in this study. MEG responses to speech and non-speech sounds were recorded, and the power and phase –locking of the eNO in 20-45Hz were analyzed.
Result:
BP had a significantly larger mean eNO power than SZ in 0-50ms and BP had a significantly larger mean eNO power than NC in 50-100ms(p=0.05).
Conclusion:
In this study, we showed different eNO to speech sounds in left hemisphere between schizophrenia, bipolar disorder, and normal controls. Consequently, eNO to speech sounds in left hemisphere could be an index to distinguish schizophrenia and bipolar disorder.