Department of Integrative Biology, University of Wisconsin - Madison, Madison, Wisconsin, USA.
Department of Biology, University of St. Thomas, Saint Paul, Minnesota, USA.
Brain Behav Evol. 2021;96(3):147-162. doi: 10.1159/000521310. Epub 2021 Dec 8.
Birdsong is well known for its role in mate attraction during the breeding season. However, many birds, including European starlings (Sturnus vulgaris), also sing outside the breeding season as part of large flocks. Song in a breeding context can be extrinsically rewarded by mate attraction; however, song in nonbreeding flocks, referred to here as gregarious song, results in no obvious extrinsic reward and is proposed to be intrinsically rewarded. The nucleus accumbens (NAC) is a brain region well known to mediate reward and motivation, which suggests it is an ideal candidate to regulate reward associated with gregarious song. The goal of this study was to provide new histochemical information on the songbird NAC and its subregions (rostral pole, core, and shell) and to begin to determine subregion-specific contributions to gregarious song in male starlings. We examined immunolabeling for tyrosine hydroxylase (TH), neurotensin, and enkephalin (ENK) in the NAC. We then examined the extent to which gregarious and sexually motivated song differentially correlated with immunolabeling for the immediate early genes FOS and ZENK in each subdivision of the NAC. We found that TH and ENK labeling within subregions of the starling NAC was generally similar to patterns seen in the core and shell of NACs in mammals and birds. Additionally, we found that gregarious song, but not sexually motivated song, positively correlated with FOS in all NAC subregions. Our observations provide further evidence for distinct subregions within the songbird NAC and suggest the NAC may play an important role in regulating gregarious song in songbirds.
鸟鸣以其在繁殖季节中吸引配偶的作用而闻名。然而，许多鸟类，包括欧洲椋鸟（Sturnus vulgaris），也会在繁殖季节之外作为大群的一部分歌唱。在繁殖背景下的歌曲可以通过吸引配偶而获得外在奖励；然而，在非繁殖的鸟群中，这里称为群居歌曲，没有明显的外在奖励，并且被认为是内在奖励的。伏隔核（NAC）是一个众所周知的调节奖励和动机的大脑区域，这表明它是调节与群居歌曲相关的奖励的理想候选区域。本研究的目的是提供有关鸣禽 NAC 及其亚区（额极、核心和壳）的新组织化学信息，并开始确定雄性椋鸟中群居歌曲的亚区特异性贡献。我们检查了 NAC 中酪氨酸羟化酶（TH）、神经降压素和脑啡肽（ENK）的免疫标记。然后，我们检查了群居和性动机歌曲与 NAC 各亚区中即时早期基因 FOS 和 ZENK 的免疫标记之间的相关性程度。我们发现，在星椋鸟 NAC 的亚区中，TH 和 ENK 的标记通常与哺乳动物和鸟类的 NAC 核心和壳中看到的模式相似。此外，我们发现群居歌曲，而不是性动机歌曲，与所有 NAC 亚区中的 FOS 呈正相关。我们的观察结果进一步证明了鸣禽 NAC 中的不同亚区，并表明 NAC 可能在调节鸣禽的群居歌曲中发挥重要作用。
