Department of Neurobiology, Hebrew University, Jerusalem, Israel.
Adv Exp Med Biol. 2013;787:411-8. doi: 10.1007/978-1-4614-1590-9_45.
Detecting rare and surprising events is a useful strategy for sensory -systems. In the human auditory system, deviance detection is indexed by an important component of the auditory event-related potentials, the mismatch negativity (MMN). Responses of single neurons in the inferior colliculus, medial geniculate body, and auditory cortex of mammals (cats, rats, and mice) show responses that share some properties with MMN: they are evoked by rare events, are preattentive (in as much as they occur in anesthetized animals), and, at least at the level of primary auditory cortex, cannot be accounted for by simple fatigue of the incoming sensory information. Here we extend these results to deviations beyond tone frequency. Recording in rat primary auditory cortex and using oddball sequences consisting of two frozen tokens of broadband noise samples, we found differences between the responses to the same token when used as the common and when used as the deviant, showing an exquisite sensitivity to the small differences between two spectro-temporally similar sounds. Similarly, differential adaptation can be demonstrated when using two word-like stimuli that have been derived from human speech but adapted to the rat auditory system. Thus, differential adaptation to common and rare sounds is present also with sounds whose complexity mirrors that of natural environments.
检测罕见和意外事件是感觉系统的一种有用策略。在人类听觉系统中，偏差检测由听觉事件相关电位的一个重要组成部分——失匹配负波（MMN）来标记。哺乳动物（猫、鼠）下丘、内侧膝状体和听觉皮层的单个神经元的反应表现出与 MMN 具有一些共同特征的反应：它们由罕见事件引发，是前注意的（只要它们发生在麻醉动物中），并且，至少在初级听觉皮层的水平上，不能用传入感觉信息的简单疲劳来解释。在这里，我们将这些结果扩展到超出音调频率的偏差。在大鼠初级听觉皮层中进行记录，并使用由两个冻结的宽带噪声样本组成的异类序列，我们发现当同一令牌用作共同令牌和用作偏差令牌时，对其的反应存在差异，这表明对两个频谱和时间相似的声音之间的微小差异具有极高的敏感性。同样，当使用源自人类语音但适应大鼠听觉系统的两个类词刺激时，可以证明差异适应。因此，对常见和罕见声音的差异适应也存在于其复杂性与自然环境相似的声音中。
