Variation in avian brain shape: relationship with size and orbital shape
Variation in avian brain shape: relationship with size and orbital shape
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DOI：
10.1111/joa.12109
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发表时间：
2013-11-01
影响因子：
2.4
通讯作者：
Endo, Hideki
中科院分区：
文献类型：
--
作者：
Kawabe, Soichiro;Shimokawa, Tetsuya;Endo, Hideki
鸟类的大脑形状有很大的差异。大脑尺寸的差异反映了物种特定的感觉能力和行为能力，这些能力和行为是在进化过程中由环境和生物因素塑造的。大多数先前的研究旨在确定影响大脑形状的因素，都使用了体积或线性测量。然而，很少有人探索对理解鸟类进化史绝对必要的三维(3D)脑几何的定量指标。本研究旨在：(I)探讨脑形状与整体脑大小的关系；及(Ii)评估脑形状与眼眶形状的关系。从计算机断层扫描图像重建禽脑内铸型，并使用三维几何形态计量学进行分析。主成分分析揭示了禽脑形态的显性区域差异及端脑与小脑、小脑与髓脑、间脑与视顶盖之间的形态相关性。通过多元回归分析确定脑形状相对于总脑大小的变化。较大的大脑与相对较细的端脑和大脑方向的差异有关。用两区块偏最小二乘法分析脑形态与眼眶形态的相关性。相对较圆的大脑，脑底弯曲的大脑与圆形的眼眶有关，而较窄的大脑，脑底平坦的大脑与更长的眼眶相关。功能相关的鸟类脑区的形状是相关的，眼眶大小和形状是影响鸟类大脑整体形状的主要因素。
There is wide variation in brain shape among birds. Differences in brain dimensions reflect species-specific sensory capacities and behavioral repertoires that are shaped by environmental and biological factors during evolution. Most previous studies aimed at defining factors impacting brain shape have used volumetric or linear measurements. However, few have explored the quantitative indices of three-dimensional (3D) brain geometry that are absolutely imperative to understanding avian evolutionary history. This study aimed: (i) to explore the relationship between brain shape and overall brain size; and (ii) to assess the relationship between brain shape and orbital shape. Avian brain endocasts were reconstructed from computed tomography images and analyzed using 3D geometric morphometrics. Principal component analysis revealed dominant regional variations in avian brain shape and shape correlations between the telencephalon and cerebellum, between the cerebellum and myelencephalon, and between the diencephalon and optic tectum. Brain shape changes relative to total brain size were determined by multivariate regression analysis. Larger brain size was associated with a relatively slender telencephalon and differences in brain orientation. The correlation between brain shape and orbital shape was assessed by two-block partial least-squares analysis. Relatively round brains with a ventrally flexed brain base were associated with rounder orbits, while narrower brains with a flat brain base were associated with more elongated orbits. The shapes of functionally associated avian brain regions are correlated, and orbital size and shape are dominant factors influencing the overall shape of the avian brain.