Van Ruijssevelt Lisbeth, De Groof Geert, Van der Kant Anne, Poirier Colline, Van Audekerke Johan, Verhoye Marleen, Van der Linden Annemie
Bio-Imaging Lab, University of Antwerp, Wilrijk, Belgium.
J Vis Exp. 2013 Jun 3(76):4369. doi: 10.3791/4369.
The neurobiology of birdsong, as a model for human speech, is a pronounced area of research in behavioral neuroscience. Whereas electrophysiology and molecular approaches allow the investigation of either different stimuli on few neurons, or one stimulus in large parts of the brain, blood oxygenation level dependent (BOLD) functional Magnetic Resonance Imaging (fMRI) allows combining both advantages, i.e. compare the neural activation induced by different stimuli in the entire brain at once. fMRI in songbirds is challenging because of the small size of their brains and because their bones and especially their skull comprise numerous air cavities, inducing important susceptibility artifacts. Gradient-echo (GE) BOLD fMRI has been successfully applied to songbirds (1-5) (for a review, see (6)). These studies focused on the primary and secondary auditory brain areas, which are regions free of susceptibility artifacts. However, because processes of interest may occur beyond these regions, whole brain BOLD fMRI is required using an MRI sequence less susceptible to these artifacts. This can be achieved by using spin-echo (SE) BOLD fMRI (7,8) . In this article, we describe how to use this technique in zebra finches (Taeniopygia guttata), which are small songbirds with a bodyweight of 15-25 g extensively studied in behavioral neurosciences of birdsong. The main topic of fMRI studies on songbirds is song perception and song learning. The auditory nature of the stimuli combined with the weak BOLD sensitivity of SE (compared to GE) based fMRI sequences makes the implementation of this technique very challenging.
鸟类鸣叫的神经生物学作为人类语言的模型，是行为神经科学中一个显著的研究领域。电生理学和分子方法能够研究少数神经元对不同刺激的反应，或者大脑大部分区域对一种刺激的反应，而基于血氧水平依赖（BOLD）的功能磁共振成像（fMRI）则兼具这两种优势，即可以同时比较整个大脑中不同刺激所诱发的神经激活情况。对鸣禽进行fMRI研究具有挑战性，因为它们的大脑体积小，而且其骨骼尤其是头骨包含许多气腔，会产生严重的磁化率伪影。梯度回波（GE）BOLD fMRI已成功应用于鸣禽（参考文献1 - 5）（综述见参考文献6）。这些研究聚焦于初级和次级听觉脑区，这些区域不存在磁化率伪影。然而，由于感兴趣的过程可能发生在这些区域之外，所以需要使用对这些伪影不太敏感的MRI序列来进行全脑BOLD fMRI研究。这可以通过使用自旋回波（SE）BOLD fMRI来实现（参考文献7, 8）。在本文中，我们描述了如何在斑胸草雀（Taeniopygia guttata）中使用这种技术，斑胸草雀是一种体重为15 - 25克的小型鸣禽，在鸟类鸣叫行为神经科学领域得到了广泛研究。对鸣禽进行fMRI研究的主要主题是鸣叫感知和鸣叫学习。刺激的听觉性质，再加上基于SE（与GE相比）的fMRI序列的BOLD敏感性较弱，使得这项技术的实施极具挑战性。
