Doeller Christian F, Opitz Bertram, Mecklinger Axel, Krick Christoph, Reith Wolfgang, Schröger Erich
Experimental Neuropsychology Unit, Department of Psychology, Saarland University, Saarbrücken, Germany.
Neuroimage. 2003 Oct;20(2):1270-82. doi: 10.1016/S1053-8119(03)00389-6.
Previous electrophysiological and neuroimaging studies suggest that the mismatch negativity (MMN) is generated by a temporofrontal network subserving preattentive auditory change detection. In two experiments we employed event-related brain potentials (ERP) and event-related functional magnetic resonance imaging (fMRI) to examine neural and hemodynamic activity related to deviance processing, using three types of deviant tones (small, medium, and large) in both a pitch and a space condition. In the pitch condition, hemodynamic activity in the right superior temporal gyrus (STG) increased as a function of deviance. Comparisons between small and medium and between small and large deviants revealed right prefrontal activation in the inferior frontal gyrus (IFG; BA 44/45) and middle frontal gyrus (MFG; BA 46), whereas large relative to medium deviants led to left and right IFG (BA 44/45) activation. In the ERP experiment the amplitude of the early MMN (90-120 ms) increased as a function of deviance, by this paralleling the right STG activation in the fMRI experiment. A U-shaped relationship between MMN amplitude and the degree of deviance was observed in a late time window (140-170 ms) resembling the right IFG activation pattern. In a subsequent source analysis constrained by fMRI activation foci, early and late MMN activity could be modeled by dipoles placed in the STG and IFG, respectively. In the spatial condition no reliable hemodynamic activation could be observed. The MMN amplitude was substantially smaller than in the pitch condition for all three spatial deviants in the ERP experiment. In contrast to the pitch condition it increased as a function of deviance in the early and in the late time window. We argue that the right IFG mediates auditory deviance detection in case of low discriminability between a sensory memory trace and auditory input. This prefrontal mechanism might be part of top-down modulation of the deviance detection system in the STG.
以往的电生理和神经影像学研究表明，失匹配负波（MMN）由一个颞额网络产生，该网络负责前注意听觉变化检测。在两个实验中，我们采用事件相关脑电位（ERP）和事件相关功能磁共振成像（fMRI）来检查与偏差处理相关的神经和血液动力学活动，在音高和空间条件下使用三种类型的偏差音调（小、中、大）。在音高条件下，右侧颞上回（STG）的血液动力学活动随偏差程度增加。小偏差与中偏差以及小偏差与大偏差之间的比较显示，额下回（IFG；BA 44/45）和额中回（MFG；BA 46）出现右侧前额叶激活，而大偏差相对于中偏差导致双侧IFG（BA 44/45）激活。在ERP实验中，早期MMN（90 - 120毫秒）的波幅随偏差程度增加，这与fMRI实验中右侧STG的激活情况相似。在一个较晚的时间窗口（140 - 170毫秒）观察到MMN波幅与偏差程度之间呈U形关系，类似于右侧IFG的激活模式。在随后受fMRI激活焦点约束的源分析中，早期和晚期MMN活动可分别由置于STG和IFG的偶极子建模。在空间条件下，未观察到可靠的血液动力学激活。在ERP实验中，所有三种空间偏差的MMN波幅均显著小于音高条件下的。与音高条件相反，在早期和晚期时间窗口中，它随偏差程度增加。我们认为，在感觉记忆痕迹与听觉输入之间辨别力较低的情况下，右侧IFG介导听觉偏差检测。这种前额叶机制可能是STG中偏差检测系统自上而下调制的一部分。
