Barkan Shay, Yom-Tov Yoram, Barnea Anat
Department of Zoology, Tel-Aviv University, Tel-Aviv, 61391, Israel.
Dev Neurobiol. 2014 Dec;74(12):1194-209. doi: 10.1002/dneu.22198. Epub 2014 Jun 17.
Evidence suggests a possible correlation between learning abilities of adults and new neuronal recruitment into their brains. The hypothesis is that this brain plasticity enables animals to adapt to environmental changes. We examined whether there are differences in neuronal recruitment between resident and migrant birds. We predicted that migrants, which are more exposed to spatial changes than residents, will recruit more new neurons. To test this, we compared neuronal recruitment in two closely related bird species - the migrant reed warbler (Acrocephalus scirpaceus), and the resident Clamorous warbler (A. Stentoreus) - during spring, summer, and autumn. Wild birds were caught, treated with BrdU and sacrificed five weeks later. New neurons were recorded in the Hippocampus and Nidopallium caudolateral. The results support our hypothesis, as more new neurons were found in the migrant species, in both brain regions and all seasons. We suggest that this phenomenon enables enhanced navigational abilities, which are required for the migratory lifestyle. However, in contrast to our hypothesis, in spring we found less new neurons in adults of both species, as compared to other seasons. We suggest that in spring, when birds settle in breeding territories, they require less spatial skills, and this might enable to reduce the cost of neuronal recruitment, as reflected by less new neurons in their brains. We also found age differences, with overall higher neuronal recruitment in juveniles. Finally, we advocate the importance of studying wild populations, for a better understanding of the adaptive significance of neuronal replacement in the vertebrate brain.
有证据表明，成年动物的学习能力与大脑中新生神经元的招募之间可能存在关联。假说认为，这种大脑可塑性使动物能够适应环境变化。我们研究了留鸟和候鸟在神经元招募方面是否存在差异。我们预测，相较于留鸟，更多暴露于空间变化的候鸟会招募更多新神经元。为了验证这一点，我们比较了两种亲缘关系相近的鸟类——迁徙的芦苇莺（Acrocephalus scirpaceus）和留居的噪大苇莺（A. Stentoreus）——在春季、夏季和秋季的神经元招募情况。捕获野生鸟类，用溴脱氧尿苷（BrdU）处理，五周后处死。在海马体和尾外侧皮质记录新生神经元。结果支持了我们的假说，因为在两个脑区以及所有季节中，迁徙物种中发现了更多的新生神经元。我们认为，这种现象能够增强导航能力，这是迁徙生活方式所必需的。然而，与我们的假说相反，在春季我们发现，与其他季节相比，两种鸟类的成年个体中新生神经元较少。我们认为，在春季，当鸟类在繁殖领地定居时，它们对空间技能的需求较低，这可能使得神经元招募成本降低，其大脑中新生神经元较少就反映了这一点。我们还发现了年龄差异，总体而言幼鸟的神经元招募更多。最后，我们主张研究野生种群对于更好地理解脊椎动物大脑中神经元替代的适应性意义具有重要性。
