Roth Timothy C, Gallagher Caitlin M, LaDage Lara D, Pravosudov Vladimir V
Department of Biology, University of Nevada, Reno, Nev., USA.
Brain Behav Evol. 2012;79(3):181-90. doi: 10.1159/000335421. Epub 2012 Jan 26.
In environments where resources are difficult to obtain and enhanced cognitive capabilities might be adaptive, brain structures associated with cognitive traits may also be enhanced. In our previous studies, we documented a clear and significant relationship among environmental conditions, memory and hippocampal structure using ten populations of black-capped chickadees (Poecile atricapillus) over a large geographic range. In addition, focusing on just the two populations from the geographical extremes of our large-scale comparison, Alaska and Kansas, we found enhanced problem-solving capabilities and reduced neophobia in a captive-raised population of black-capped chickadees originating from the energetically demanding environment (Alaska) relative to conspecifics from the milder environment (Kansas). Here, we focused on three brain regions, the arcopallium (AP), the nucleus taeniae of the amygdala and the lateral striatum (LSt), that have been implicated to some extent in aspects of these behaviors in order to investigate whether potential differences in these brain areas may be associated with our previously detected differences in cognition. We compared the variation in neuron number and volumes of these regions between these populations, in both wild-caught birds and captive-raised individuals. Consistent with our behavioral observations, wild-caught birds from Kansas had a larger AP volume than their wild-caught conspecifics from Alaska, which possessed a higher density of neurons in the LSt. However, there were no other significant differences between populations in the wild-caught and captive-raised groups. Interestingly, individuals from the wild had larger LSt and AP volumes with more neurons than those raised in captivity. Overall, we provide some evidence that population-related differences in problem solving and neophobia may be associated with differences in volume and neuron numbers of our target brain regions. However, the relationship is not completely clear, and our study raises numerous questions about the relationship between the brain and behavior, especially in captive animals.
在资源难以获取且增强的认知能力可能具有适应性的环境中，与认知特征相关的脑结构也可能得到增强。在我们之前的研究中，我们利用分布在大范围地理区域的十个黑顶山雀（Poecile atricapillus）种群，记录了环境条件、记忆和海马体结构之间清晰且显著的关系。此外，仅关注我们大规模比较中地理极端位置的两个种群，即阿拉斯加和堪萨斯，我们发现，相对于来自较温和环境（堪萨斯）的同物种个体，源自能量需求较高环境（阿拉斯加）的圈养黑顶山雀种群具有更强的解决问题能力和更低的新事物恐惧。在这里，我们聚焦于三个脑区，即弓状皮质（AP）、杏仁核的带状核和外侧纹状体（LSt），这些脑区在一定程度上与这些行为的某些方面有关联，以便研究这些脑区的潜在差异是否可能与我们之前检测到的认知差异相关。我们比较了这些种群在野生捕获鸟类和圈养个体中这些区域的神经元数量和体积变化。与我们的行为观察结果一致，来自堪萨斯的野生捕获鸟类的AP体积比来自阿拉斯加的野生捕获同物种个体更大，而阿拉斯加的野生捕获个体在LSt中具有更高的神经元密度。然而，在野生捕获和圈养组的种群之间没有其他显著差异。有趣的是，野生个体的LSt和AP体积更大，神经元数量也比圈养个体更多。总体而言，我们提供了一些证据表明，与种群相关的解决问题能力和新事物恐惧差异可能与我们目标脑区的体积和神经元数量差异有关。然而，这种关系并不完全清晰，我们的研究提出了许多关于大脑与行为之间关系的问题，尤其是在圈养动物中。
