Correlations between differences in animal behavior and brain structures have been used to infer function of those structures. Brain region size has especially been suggested to be important for an animal’s behavioral capability, controlled by specific brain regions. The oval nucleus of the mesopallium (MO) is part of the anterior forebrain vocal learning pathway in the parrot brain. Here, we compare brain volume and total number of neurons in MO of three parrot species (the peach-fronted conure, Eupsittula aurea, the peach-faced lovebird, Agapornis roseicollis, and the budgerigar, Melopsittacus undulatus), relating the total neuron numbers with the vocal response to playbacks of each species. We find that individuals with the highest number of neurons in MO had the shortest vocal latency. The peach-fronted conures showed the shortest vocal latency and largest number of MO neurons, the peach-faced lovebird had intermediary levels of both, and the budgerigar had the longest latency and least number of neurons. These findings indicate the MO nucleus as one candidate region that may be part of what controls the vocal capacity of parrots.
Brain Behav Evol

中文翻译：

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中皮卵圆核的特征与鹦鹉对回放的声音反应之间的关系

动物行为差异与大脑结构之间的相关性已被用于推断这些结构的功能。大脑区域的大小特别被认为对动物的行为能力很重要，由特定的大脑区域控制。mesopallium (MO) 的椭圆形核是鹦鹉大脑中前脑发声学习通路的一部分。在这里，我们比较了三种鹦鹉物种（桃额锥鹦鹉，Eupsittula aurea，桃脸爱情鸟，Agapornis roseicollis和虎皮鹦鹉，Melopsittacus undulatus）的脑容量和神经元总数)，将总神经元数与对每个物种回放的声音反应相关联。我们发现 MO 中神经元数量最多的个体的发声潜伏期最短。桃脸锥鸟的发声潜伏期最短，MO 神经元数量最多，桃脸爱情鸟两者均处于中间水平，虎皮鹦鹉的潜伏期最长，神经元数量最少。这些发现表明 MO 核是一个候选区域，可能是控制鹦鹉发声能力的一部分。
大脑行为进化