Shimano Satomi, Onitsuka Toshiaki, Oribe Naoya, Maekawa Toshihiko, Tsuchimoto Rikako, Hirano Shogo, Ueno Takefumi, Hirano Yoji, Miura Tomofumi, Kanba Shigenobu
Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Bipolar Disord. 2014 Sep;16(6):592-9. doi: 10.1111/bdi.12208. Epub 2014 May 8.
Mismatch negativity (MMN) and its magnetic counterpart (MMNm) are thought to reflect an automatic process that detects a difference between an incoming stimulus and the sensory memory trace of preceding stimuli. In patients with schizophrenia, an attenuation of the MMN/MMNm amplitude has been repeatedly reported. Heschl's gyrus (HG) is one of the major generators of MMN and the functional alteration of HG has been reported in patients with bipolar disorder. The present study investigated the pitch-MMNm in patients with bipolar disorder using whole-head 306-ch magnetoencephalography (MEG).
Twenty-two patients and 22 healthy controls participated in this study. Subjects were presented with two types of auditory stimulus sequences. One consisted of 1,000 Hz standards (probability = 90%) and 1,200 Hz deviants (probability = 10%), and the other consisted of 1,000 Hz standards (90%) and 1,200 Hz deviants (10%). These two tasks were each performed twice. Event-related brain responses to standard tones were subtracted from responses to deviant tones.
Patients with bipolar disorder showed a significant bilateral reduction in magnetic global field power (mGFP) amplitudes (p = 0.02) and dipole moments of the MMNm (p = 0.04) compared with healthy controls. Patients with admission experience showed significantly reduced mGFP amplitudes of MMNm compared with patients without admission experience (p = 0.004). Additionally, patients with more severe manic symptoms had smaller mGFP amplitudes of MMNm (ρ = -0.50, p = 0.05).
The results of this study suggest that patients with bipolar disorder may exhibit preattentive auditory dysfunction indexed by reduced pitch-MMNm responses. Pitch-MMNm could be a potential trait marker reflecting the global severity of bipolar disorder.
失匹配负波（MMN）及其磁对应成分（MMNm）被认为反映了一种自动过程，该过程可检测传入刺激与先前刺激的感觉记忆痕迹之间的差异。在精神分裂症患者中，MMN/MMNm波幅衰减已被多次报道。颞横回（HG）是MMN的主要产生源之一，且双相情感障碍患者中已报道HG存在功能改变。本研究使用全头306通道脑磁图（MEG）对双相情感障碍患者的音调MMNm进行了研究。
22例患者和22名健康对照参与了本研究。向受试者呈现两种类型的听觉刺激序列。一种由1000Hz的标准音（概率=90%）和1200Hz的偏差音（概率=10%）组成，另一种由1000Hz的标准音（90%）和1200Hz的偏差音（10%）组成。这两项任务各进行两次。将对偏差音的反应减去对标准音的事件相关脑反应。
与健康对照相比，双相情感障碍患者的磁全域场功率（mGFP）波幅（p=0.02）和MMNm的偶极矩（p=0.04）出现显著双侧降低。有入院经历的患者与无入院经历的患者相比，MMNm的mGFP波幅显著降低（p=0.004）。此外，躁狂症状更严重的患者MMNm的mGFP波幅更小（ρ=-0.50，p=0.05）。
本研究结果表明，双相情感障碍患者可能表现出以音调MMNm反应降低为指标的前注意听觉功能障碍。音调MMNm可能是反映双相情感障碍整体严重程度的潜在特质标志物。
