Gale Samuel D, Perkel David J
Graduate Program in Neurobiology and Behavior, University of Washington, Seattle, WA 98195, USA.
J Neurophysiol. 2005 Apr;93(4):1871-9. doi: 10.1152/jn.01053.2004. Epub 2004 Nov 17.
Vocal learning in songbirds requires a basal ganglia circuit termed the anterior forebrain pathway (AFP). The AFP is not required for song production, and its role in song learning is not well understood. Like the mammalian striatum, the striatal component of the AFP, Area X, receives dense dopaminergic innervation from the midbrain. Since dopamine (DA) clearly plays a crucial role in basal ganglia-mediated motor control and learning in mammals, it seems likely that DA signaling contributes importantly to the functions of Area X as well. In this study, we used voltammetric methods to detect subsecond changes in extracellular DA concentration to gain better understanding of the properties and regulation of DA release and uptake in Area X. We electrically stimulated Ca(2+)- and action potential-dependent release of an electroactive substance in Area X brain slices and identified the substance as DA by the voltammetric waveform, electrode selectivity, and neurochemical and pharmacological evidence. As in the mammalian striatum, DA release in Area X is depressed by autoinhibition, and the lifetime of extracellular DA is strongly constrained by monoamine transporters. These results add to the known physiological similarities of the mammalian and songbird striatum and support further use of voltammetry in songbirds to investigate the role of basal ganglia DA in motor learning.
鸣禽的发声学习需要一个称为前脑通路（AFP）的基底神经节回路。歌曲产生并不需要AFP，其在歌曲学习中的作用尚不清楚。与哺乳动物的纹状体一样，AFP的纹状体部分X区从中脑接受密集的多巴胺能神经支配。由于多巴胺（DA）在哺乳动物基底神经节介导的运动控制和学习中显然起着关键作用，因此DA信号传导似乎也对X区的功能起着重要作用。在本研究中，我们使用伏安法检测细胞外DA浓度的亚秒级变化，以更好地了解X区DA释放和摄取的特性及调节。我们在X区脑片中电刺激了一种电活性物质的Ca(2+)和动作电位依赖性释放，并通过伏安波形、电极选择性以及神经化学和药理学证据确定该物质为DA。与哺乳动物纹状体一样，X区的DA释放受自身抑制作用抑制，细胞外DA的寿命受到单胺转运体的强烈限制。这些结果增加了已知的哺乳动物和鸣禽纹状体的生理相似性，并支持在鸣禽中进一步使用伏安法来研究基底神经节DA在运动学习中的作用。
