Neurosciences Graduate Program, University of California, San Diego, La Jolla, CA, USA.
J Neurophysiol. 2013 Feb;109(3):721-33. doi: 10.1152/jn.00262.2012. Epub 2012 Nov 14.
Changes in inhibition during development are well documented, but the role of inhibition in adult learning-related plasticity is not understood. In songbirds, vocal recognition learning alters the neural representation of songs across the auditory forebrain, including the caudomedial nidopallium (NCM), a region analogous to mammalian secondary auditory cortices. Here, we block local inhibition with the iontophoretic application of gabazine, while simultaneously measuring song-evoked spiking activity in NCM of European starlings trained to recognize sets of conspecific songs. We find that local inhibition differentially suppresses the responses to learned and unfamiliar songs and enhances spike-rate differences between learned categories of songs. These learning-dependent response patterns emerge, in part, through inhibitory modulation of selectivity for song components and the masking of responses to specific acoustic features without altering spectrotemporal tuning. The results describe a novel form of inhibitory modulation of the encoding of learned categories and demonstrate that inhibition plays a central role in shaping the responses of neurons to learned, natural signals.
发育过程中抑制作用的变化已有相关记载，但抑制作用在成年学习相关可塑性中的作用尚不清楚。在鸣禽中，声音识别学习会改变听觉前脑（包括尾侧中脑隔核（NCM）在内）中歌曲的神经表现，该区域类似于哺乳动物的次级听觉皮层。在这里，我们通过局部给予荷包牡丹碱来阻断局部抑制，同时测量经过训练以识别同种鸟鸣集合的欧洲椋鸟 NCM 中的鸟鸣诱发的尖峰活动。我们发现，局部抑制会有差异地抑制对已学习歌曲和不熟悉歌曲的反应，并增强学习歌曲类之间的尖峰率差异。这些依赖于学习的反应模式的出现，部分是通过对歌曲成分的选择性进行抑制性调节，以及对特定声音特征的反应进行掩蔽，而不会改变频谱时间调谐。研究结果描述了一种新的抑制性调节形式，用于对已学习类别的编码，并证明抑制作用在塑造神经元对学习、自然信号的反应方面起着核心作用。
