Hara Erina, Perez Jemima M, Whitney Osceola, Chen Qianqian, White Stephanie A, Wright Timothy F
Department of Biology, New Mexico State University, Las Cruces, NM 88003, United States.
Department of Biology, New Mexico State University, Las Cruces, NM 88003, United States.
Behav Brain Res. 2015 Apr 15;283:22-9. doi: 10.1016/j.bbr.2015.01.017. Epub 2015 Jan 16.
Vocal learning underlies acquisition of both language in humans and vocal signals in some avian taxa. These bird groups and humans exhibit convergent developmental phases and associated brain pathways for vocal communication. The transcription factor FoxP2 plays critical roles in vocal learning in humans and songbirds. Another member of the forkhead box gene family, FoxP1 also shows high expression in brain areas involved in vocal learning and production. Here, we investigate FoxP2 and FoxP1 mRNA and protein in adult male budgerigars (Melopsittacus undulatus), a parrot species that exhibits vocal learning as both juveniles and adults. To examine these molecules in adult vocal learners, we compared their expression patterns in the budgerigar striatal nucleus involved in vocal learning, magnocellular nucleus of the medial striatum (MMSt), across birds with different vocal states, such as vocalizing to a female (directed), vocalizing alone (undirected), and non-vocalizing. We found that both FoxP2 mRNA and protein expressions were consistently lower in MMSt than in the adjacent striatum regardless of the vocal states, whereas previous work has shown that songbirds exhibit down-regulation in the homologous region, Area X, only after singing alone. In contrast, FoxP1 levels were high in MMSt compared to the adjacent striatum in all groups. Taken together these results strengthen the general hypothesis that FoxP2 and FoxP1 have specialized expression in vocal nuclei across a range of taxa, and suggest that the adult vocal plasticity seen in budgerigars may be a product of persistent down-regulation of FoxP2 in MMSt.
发声学习是人类语言习得以及某些鸟类类群发声信号获取的基础。这些鸟类群体和人类在发声交流方面展现出趋同的发育阶段及相关的脑通路。转录因子FoxP2在人类和鸣禽的发声学习中发挥着关键作用。叉头框基因家族的另一个成员FoxP1在参与发声学习和发声产生的脑区也呈现高表达。在此，我们研究成年雄性虎皮鹦鹉（Melopsittacus undulatus）中的FoxP2和FoxP1 mRNA及蛋白质，虎皮鹦鹉是一种在幼年和成年时均表现出发声学习能力的鹦鹉物种。为了在成年发声学习者中检测这些分子，我们比较了它们在参与发声学习的虎皮鹦鹉纹状体核——内侧纹状体大细胞核（MMSt）中的表达模式，这些鸟处于不同的发声状态，如向雌性发声（定向发声）、独自发声（非定向发声）以及不发声。我们发现，无论发声状态如何，MMSt中FoxP2 mRNA和蛋白质的表达始终低于相邻的纹状体，而此前的研究表明，鸣禽仅在独自鸣叫后，其同源区域X区才会出现下调。相反，与相邻纹状体相比，所有组中MMSt的FoxP1水平都很高。综合这些结果强化了一个普遍的假设，即FoxP2和FoxP1在一系列类群的发声核中具有特殊表达，并表明虎皮鹦鹉中所见的成年发声可塑性可能是MMSt中FoxP2持续下调的产物。
