大脑听皮层外中枢在听觉注意状态调控中的作用机制

Auditory perception is obviously modulated by the attentional state of brain. Revealing the essence of this phenomenon is a critical step to fully understand the neural mechanism of brain sensory system. Previously, we have found that the neurons of the auditory cortex showed different electrical activities under different attentional states (actively discriminating sounds or passively listening to sounds). Also, the effects of attentional state differed among the different sub-regions of auditory cortex. The reason of such differences remains unclear. In this project, we will focus on the brain regions outside the auditory cortex, including prefrontal cortex, amygdala, basal ganglia and thalamus. We will systemically examine the relationship between the neural activities in these non-auditory regions and attentional state; and also testify how the neural activities of the auditory cortex are affected, as the neurons of non-auditory regions are artificially activated by electrical stimulation. We will attempt to reveal how the non-auditory regions and auditory cortex constitute a neural network involving in the modulation of attentional state.

听觉功能是受到大脑注意状态调控的，充分揭示这一现象的本质是全面了解大脑听觉神经机制的必要环节。我们的前期研究工作发现，大脑听皮层在不同的注意状态下（主动辨别声音和被动听声音）神经元电活动明显不同，并且听皮层内不同区域的反应也不尽相同。造成这种差异的原因目前尚不清楚。为此，本项目着眼于听皮层以外的大脑前额皮层、杏仁核、基底核及丘脑等中枢区域，系统地检测听皮层以外神经元活动与注意状态的相关性；力图详细阐明前额皮层等听皮层以外神经元活动对听皮层神经元活动的影响。

在本项目执行期间，我们成功建立了在体多通道单细胞细胞外电生理记录技术，实现了在动物自由运动条件下稳定记录动作电位(spike)和局部场电位（LFP）的设想。进而将这一技术与行为学实验方法相结合，系统研究了实验动物在主动辨别不同声音刺激时和被动接受声音刺激时，听皮层(AC)和前额皮层等听皮层外各脑区神经元电活动的变化特征，解析了不同脑区在听觉认知行为中所承担的功能，探讨了注意状态对各层级神经中枢活动的调控机制。我们的研究结果显示除大脑听皮层之外，大脑基底核中的壳核（PU），苍白球(GP)，杏仁核（AMY）和内侧前额皮层(mPFC)等脑区的神经元都与听觉识别行为有关，并且各自所担负的功能可能不同。听皮层神经元负责分析识别声音刺激的物理参数， PU，GP，AMY和mPFC等听皮层外脑区的神经元对物理参数的识别功能逐渐减退，而对声音刺激所代表的行为意义的认知功能逐渐增强。特别是mPFC区神经元基本上完全丧失了对声音物理参数的区分能力，只负责解读行为意义。这些听皮层外神经元的活动明显受到注意状态的影响，当实验动物不关注声音刺激时，其电活动水平显著降低。我们还证实了AC区和mPFC区之间存在着功能连接，并且受注意状态的调节。这些研究结果为全面了解从听觉产生到行为反应的神经网络的构成以及工作机制提供了重要依据，填补了听觉神经研究领域的空白。截止本报告撰写时为止，共发表了7篇SCI论文，另有2两篇已经投稿正处于修回阶段。