Eliades Steven J, Wang Xiaoqin
Laboratory of Auditory Neurophysiology, Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Cereb Cortex. 2005 Oct;15(10):1510-23. doi: 10.1093/cercor/bhi030. Epub 2005 Feb 2.
Single neurons in the primate auditory cortex exhibit vocalization-related modulations (excitatory or inhibitory) during self-initiated vocal production. Previous studies have shown that these modulations of cortical activity are variable in individual neurons' responses to multiple instances of vocalization and diverse between different cortical neurons. The present study investigated dynamic patterns of vocalization-related modulations and demonstrated that much of the variability in cortical modulations was related to the acoustic structures of self-produced vocalization. We found that suppression of single unit activity during multi-phrased vocalizations was temporally specific in that it was maintained during each phrase, but was released between phrases. Furthermore, the degree of suppression or excitation was correlated to the mean energy and frequency of the produced vocalizations, accounting for much of the response variability between multiple instances of vocalization. Simultaneous recordings of pairs of neurons from a single electrode revealed that the modulations by self-produced vocalizations in nearby neurons were largely uncorrelated. Additionally, vocalization-induced suppression was found to be preferentially distributed to upper cortical layers. Finally, we showed that the summation of all auditory cortical activity during vocalization, including both single and multi-unit responses, was weakly excitatory, consistent with observations from studies of the human brain during speech.
在灵长类动物听觉皮层中，单个神经元在自发发声过程中表现出与发声相关的调制（兴奋性或抑制性）。先前的研究表明，这些皮层活动的调制在单个神经元对多次发声实例的反应中是可变的，并且在不同的皮层神经元之间存在差异。本研究调查了与发声相关的调制的动态模式，并证明皮层调制中的许多变异性与自我产生的发声的声学结构有关。我们发现，在多短语发声过程中单个单元活动的抑制在时间上具有特异性，即它在每个短语期间保持，但在短语之间释放。此外，抑制或兴奋的程度与所产生发声的平均能量和频率相关，这解释了多次发声实例之间反应变异性的大部分原因。从单个电极对成对神经元的同步记录显示，附近神经元中自我产生的发声引起的调制在很大程度上是不相关的。此外，发现发声诱导的抑制优先分布在上皮层。最后，我们表明，发声期间所有听觉皮层活动的总和，包括单个和多单元反应，是弱兴奋性的，这与对人类大脑在言语过程中的研究观察结果一致。
