Iwaniuk Andrew N, Gutierrez-Ibanez Cristian, Pakan Janelle M P, Wylie Douglas R
Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, Alta., Canada.
Brain Behav Evol. 2010;75(2):122-37. doi: 10.1159/000311729. Epub 2010 May 28.
Recent studies have shown that the relative sizes of visual regions in the avian brain are correlated with behavioral differences among species. Despite the fact that the tectofugal pathway is the primary source of visual input to the avian brain, detailed interspecific comparisons of the relative size of nuclei within the pathway, the optic tectum, nucleus rotundus and entopallium, are wanting. Here, we examine the allometric scaling relationships of each of these brain regions relative to the brain as a whole using conventional and phylogenetically based statistics across 113 species. Our results show that the relative size of tectofugal regions of the avian brain varies significantly among avian orders. More specifically, waterfowl (Anseriformes), parrots (Psittaciformes) and owls (Strigiformes) have significantly smaller tectofugal brain regions than other birds. At the opposite end of the spectrum, we found little evidence for the significant enlargement of any tectofugal region among the orders that we sampled. The lack of such hypertrophy likely reflects the heterogeneous organization of the optic tectum, nucleus rotundus and entopallium. We therefore speculate that if neural adaptations do exist in the avian tectofugal pathway that are correlated with behavior, they occur at a more refined level than simple volumetrics.
最近的研究表明，鸟类大脑中视觉区域的相对大小与物种间的行为差异相关。尽管离顶盖通路是鸟类大脑视觉输入的主要来源，但对于该通路内各核团（视顶盖、圆核和内嗅皮质）相对大小的详细种间比较仍很缺乏。在此，我们使用传统统计方法和基于系统发育的统计方法，对113个物种的这些脑区相对于整个大脑的异速生长缩放关系进行了研究。我们的结果表明，鸟类大脑离顶盖区域的相对大小在鸟类目之间存在显著差异。更具体地说，水禽（雁形目）、鹦鹉（鹦形目）和猫头鹰（鸮形目）的离顶盖脑区明显小于其他鸟类。在光谱的另一端，我们在所采样的目中几乎没有发现任何离顶盖区域显著增大的证据。这种肥大现象的缺乏可能反映了视顶盖、圆核和内嗅皮质的异质性组织。因此，我们推测，如果鸟类离顶盖通路中确实存在与行为相关的神经适应性变化，那么它们发生在比简单体积测量更精细的层面上。
