Shaevitz Sarita S, Theunissen Frédéric E
University of California, Psychology Department, Berkeley, CA 94720-1650, USA.
J Neurophysiol. 2007 Nov;98(5):2747-64. doi: 10.1152/jn.00294.2007. Epub 2007 Sep 26.
A key discovery that has emerged from studies of the vocal system in songbirds is that neurons in these regions respond preferentially to playback of the bird's own song (BOS). This BOS selectivity is not a general property of neurons in primary and secondary auditory forebrain regions, field L and caudolateral mesopallium (CLM). Moreover, anatomical studies have been unable to conclusively define a direct projection from field L and/or CLM to HVC, a central structure for integrating sensory and motor information in the vocal system. To examine the communication between these regions, we used simultaneous dual-electrode recording in anesthetized male zebra finches and cross-correlation analysis to estimate the functional connectivity between auditory areas, field L and CLM, and HVC. We found that >or=18% of neurons in field L and 33% of neurons in CLM are functionally connected to HVC, most with auditory forebrain leading-HVC latencies ranging from 0.5 to 15 ms. These results indicate that field L and CLM communicate extensively with HVC through both direct and indirect anatomical connections. To further explore the role of the auditory forebrain cells that are functionally connected with HVC, we assessed their responsiveness and selectivity for a variety of natural and synthetic auditory stimuli. We found that field L and CLM neurons that are functionally connected to HVC exhibit generic auditory forebrain properties including the lack of BOS selectivity. This finding puts further constraints on the neural architecture and the nature of the nonlinearity that leads to BOS-selective auditory responses in the vocal control nuclei.
对鸣禽发声系统研究中出现的一个关键发现是，这些区域的神经元对播放该鸟类自己的歌声（BOS）有优先反应。这种BOS选择性并非初级和次级听觉前脑区域、L区和尾外侧中脑皮质（CLM）中神经元的普遍特性。此外，解剖学研究未能最终确定从L区和/或CLM到HVC的直接投射，HVC是发声系统中整合感觉和运动信息的核心结构。为了研究这些区域之间的通信，我们在麻醉的雄性斑胸草雀中使用同步双电极记录和互相关分析来估计听觉区域L区、CLM和HVC之间的功能连接性。我们发现，L区中≥18%的神经元和CLM中33%的神经元与HVC存在功能连接，大多数听觉前脑领先于HVC的潜伏期为0.5至15毫秒。这些结果表明，L区和CLM通过直接和间接的解剖连接与HVC广泛通信。为了进一步探索与HVC存在功能连接的听觉前脑细胞的作用，我们评估了它们对各种自然和合成听觉刺激的反应性和选择性。我们发现，与HVC存在功能连接的L区和CLM神经元表现出一般的听觉前脑特性，包括缺乏BOS选择性。这一发现对导致发声控制核中BOS选择性听觉反应的神经结构和非线性性质施加了进一步的限制。
