Institute for Biomagnetism and Biosignalanalysis, University of Münster, Malmedyweg 15, D-48149, Münster, Germany; Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, D-48149, Münster, Germany.
Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Münster, D-48149, Münster, Germany; Institute of Medical Psychology and Systems Neuroscience, University of Münster, Von-Esmarch-Str. 52, D-48149, Münster, Germany.
Neuroimage. 2019 May 1;191:367-379. doi: 10.1016/j.neuroimage.2019.01.057. Epub 2019 Feb 1.
Hemispheric asymmetries play an important role in multiple cerebral functions. Asymmetries in prefrontal cortex (PFC) function have been suggested to regulate emotional processing in that right-hemispheric dominance biases towards negative affect, whereas left PFC dominance favors positive affect. This study used transcranial magnetic stimulation to test the causal role of prefrontal asymmetries in the processing of emotional stimuli. To experimentally induce hemispheric asymmetries, 21 healthy volunteers underwent two separate sessions of inhibitory continuous theta burst stimulation (cTBS) to the left versus right dorsolateral prefrontal cortex. Each stimulation was followed by magnetoencephalographic (MEG) recordings of event-related fields elicited by visually presented emotional words in a silent reading task and a subsequent behavioral emotion categorization task. The asymmetry manipulation influenced valence processing of words in early, mid-latency and late time intervals in right occipitotemporal and parietal brain regions. Left-sided cTBS (inducing right-hemispheric dominance) consistently resulted in enhanced brain responses to negative words, while right-sided cTBS (inducing left-hemispheric dominance) enhanced responses to positive words. On a behavioral level, right-hemispheric dominance resulted in more categorization matches of negative compared to positive words, while left-hemispheric dominance resulted in reverse effects. These results provide direct evidence that bottom-up valence processing is influenced by prefrontal hemispheric asymmetry.
大脑半球的不对称性在多种大脑功能中起着重要作用。前额叶皮层（PFC）功能的不对称性被认为可以调节情绪处理，即右半球优势偏向负性情绪，而左 PFC 优势偏向正性情绪。本研究使用经颅磁刺激来测试前额叶不对称性在情绪刺激处理中的因果作用。为了实验诱导半球不对称性，21 名健康志愿者接受了左、右背外侧前额叶皮层的两种不同的抑制性连续 theta 爆发刺激（cTBS）。每次刺激后，通过静息阅读任务中视觉呈现的情绪词诱发的事件相关磁场（MEG）记录和随后的行为情绪分类任务，记录了磁场记录。不对称性操作影响了右枕颞和顶叶脑区中单词的早期、中期和晚期潜伏期的效价处理。左侧 cTBS（诱导右半球优势）一致导致对负性单词的大脑反应增强，而右侧 cTBS（诱导左半球优势）增强了对正性单词的反应。在行为层面上，右半球优势导致对负性单词的分类匹配多于正性单词，而左半球优势则产生相反的效果。这些结果提供了直接证据，表明自下而上的效价处理受到前额叶半球不对称性的影响。
