The mismatch negativity is a cortical response to auditory changes and its reduction is a consistent finding in schizophrenia. Recent evidence revealed that the human brain detects auditory changes already at subcortical stages of the auditory pathway. This finding, however, raises the question where in the auditory hierarchy the schizophrenic deficit first evolves and whether the well-known cortical deficit may be a consequence of dysfunction at lower hierarchical levels. Finally, it should be resolved whether mismatch profiles differ between schizophrenia and affective disorders which exhibit auditory processing deficits as well. We used functional magnetic resonance imaging to assess auditory mismatch processing in 29 patients with schizophrenia, 27 patients with major depression, and 31 healthy control subjects. Analysis included whole-brain activation, region of interest, path and connectivity analysis. In schizophrenia, mismatch deficits emerged at all stages of the auditory pathway including the inferior colliculus, thalamus, auditory, and prefrontal cortex. In depression, deficits were observed in the prefrontal cortex only. Path analysis revealed that activation deficits propagated from subcortical to cortical nodes in a feed-forward mechanism. Finally, both patient groups exhibited reduced connectivity along this processing stream. Auditory mismatch impairments in schizophrenia already manifest at the subcortical level. Moreover, subcortical deficits contribute to the well-known cortical deficits and show specificity for schizophrenia. In contrast, depression is associated with cortical dysfunction only. Hence, schizophrenia and major depression exhibit different neural profiles of sensory processing deficits. Our findings add to a converging body of evidence for brainstem and thalamic dysfunction as a hallmark of schizophrenia.

中文翻译：

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精神分裂症的听觉变化皮层下检出受损但不是严重抑郁症

失配阴性是皮质对听觉变化的反应，其减少是精神分裂症的一致发现。最近的证据表明，人脑已经在听觉通路的皮层下阶段检测到听觉变化。然而，这一发现提出了一个问题，即在听觉层次中精神分裂症缺陷首先发生在哪里，以及众所周知的皮质缺陷是否可能是较低层次的功能障碍的结果。最后，应该解决精神分裂症和情感障碍之间的失配情况是否不同，精神障碍也表现出听觉处理缺陷。我们使用功能磁共振成像来评估29例精神分裂症，27例重度抑郁症患者和31例健康对照者的听觉失配过程。分析包括全脑激活，关注区域，路径和连接性分析。在精神分裂症中，在听觉途径的所有阶段都出现失配缺陷，包括下丘，丘脑，听觉和前额叶皮层。在抑郁症中，仅在前额叶皮层中观察到缺陷。路径分析表明，激活缺陷在前馈机制中从皮层下扩散到皮层。最后，两个患者组在该处理流中均显示出降低的连通性。精神分裂症的听觉失配障碍已经在皮层下水平表现出来。此外，皮层下缺损导致众所周知的皮层缺损，并显示出对精神分裂症的特异性。相反，抑郁仅与皮质功能障碍有关。因此，精神分裂症和重度抑郁症表现出不同的神经系统感觉处理缺陷。我们的发现为脑干和丘脑功能障碍提供了越来越多的证据，这是精神分裂症的标志。