Neural specialization for hovering in hummingbirds: Hypertrophy of the pretectal nucleus lentiformis mesencephali
Neural specialization for hovering in hummingbirds: Hypertrophy of the pretectal nucleus lentiformis mesencephali
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DOI：
10.1002/cne.21098
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发表时间：
2007-01-10
影响因子：
2.5
通讯作者：
Wylie, Douglas R. W.
中科院分区：
文献类型：
--
作者：
Iwaniuk, Andrew N.;Wylie, Douglas R. W.
蜂鸟拥有一系列的形态和生理特化，使它们能够在空中盘旋，从而在较长时间内保持稳定的位置。在鸟类中，这种持续的盘旋是蜂鸟独有的，但这种行为背后可能的神经专门化还没有被研究过。视动反应(OKR)是促进稳定的几种行为之一。在鸟类中，OKR是由基础视根核(NBOR)和顶盖前豆状中脑核(LM)产生的。由于在悬停过程中的稳定依赖于OKR，我们预测蜂鸟的nBOR和Lm将显著增大。我们研究了13目37种鸟类的nBOR、Lm和其他视觉核团的相对大小，其中包括9种蜂鸟。还包括三种短时间盘旋的物种(短暂的悬停鸟；翠鸟、红隼和食蜜鸣鸟)。我们的结果表明，与其他鸟类相比，蜂鸟的LM显著肥大。在短暂的悬浮者中，有一个适度的放大，但没有达到蜂鸟的程度。然而，在nBOR或所测量的其他视觉核团：膝状体外侧核、腹侧部和视顶盖，则不存在相同程度的肥大。这种Lm而不是其他视觉核团的选择性肥大表明，Lm内的方向选择性视动神经元对持续悬停飞行至关重要，因为它们在OKR和凝视稳定中起着重要作用。
Hummingbirds possess an array of morphological and physiological specializations that allow them hover such that they maintain a stable position in space for extended periods. Among birds, this sustained hovering is unique to hummingbirds, but possible neural specializations underlying this behavior have not been investigated. The optokinetic response (OKR) is one of several behaviors that facilitates stabilization. In birds, the OKR is generated by the nucleus of the basal optic root (nBOR) and pretectal nucleus lentiformis mesencephali (LM). Because stabilization during hovering is dependent on the OKR, we predicted that nBOR and LM would be significantly enlarged in hummingbirds. We examined the relative size of nBOR, LM, and other visual nuclei of 37 species of birds from 13 orders, including nine hummingbird species. Also included were three species that hover for short periods of time (transient hoverers; a kingfisher, a kestrel, and a nectarivorous songbird). Our results demonstrate that, relative to brain volume, LM is significantly hypertrophied in hummingbirds compared with other birds. In the transient hoverers, there is a moderate enlargement of the LM, but not to the extent found in the hummingbirds. The same degree of hypertrophy is not, however, present in nBOR or the other visual nuclei measured: nucleus geniculatus lateralis, pars ventralis, and optic tectum. This selective hypertrophy of LM and not other visual nuclei suggests that the direction-selective optokinetic neurons in LM are critical for sustained hovering flight because of their prominent role in the OKR and gaze stabilization.