Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal.
Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal.
Neuroimage. 2018 Jan 15;165:265-277. doi: 10.1016/j.neuroimage.2017.10.027. Epub 2017 Oct 16.
The auditory pathway is widely distributed throughout the brain, and is perhaps one of the most interesting networks in the context of neuroplasticity. Accurate mapping of neural activity in the entire pathway, preferably noninvasively, and with high resolution, could be instrumental for understanding such longitudinal processes. Functional magnetic resonance imaging (fMRI) has clear advantages for such characterizations, as it is noninvasive, provides relatively high spatial resolution and lends itself for repetitive studies, albeit relying on an indirect neurovascular coupling to deliver its information. Indeed, fMRI has been previously used to characterize the auditory pathway in humans and in rats. In the mouse, however, the auditory pathway has insofar only been mapped using manganese-enhanced MRI. Here, we describe a novel setup specifically designed for high-resolution mapping of the mouse auditory pathway using high-field fMRI. Robust and consistent Blood-Oxygenation-Level-Dependent (BOLD) responses were documented along nearly the entire auditory pathway, from the cochlear nucleus (CN), through the superior olivary complex (SOC), nuclei of the lateral lemniscus (LL), inferior colliculus (IC) and the medial geniculate body (MGB). By contrast, clear BOLD responses were not observed in auditory cortex (AC) in this study. Diverse BOLD latencies were mapped ROI- and pixel-wise using coherence analysis, evidencing different averaged BOLD time courses in different auditory centers. Some degree of tonotopy was identified in the IC, SOC, and MGB in the pooled dataset though it could not be assessed per subject due to a lack of statistical power. Given the importance of the mouse model in plasticity studies, animal models, and optogenetics, and fMRI's potential to map dynamic responses to specific cues, this first fMRI study of the mouse auditory pathway paves the way for future longitudinal studies studying brain-wide auditory-related activity in vivo.
听觉通路广泛分布于大脑中，在神经可塑性方面，它可能是最有趣的网络之一。准确地绘制整个通路的神经活动图谱，最好是非侵入性的，具有高分辨率，可以帮助我们理解这些纵向过程。功能磁共振成像（fMRI）在这些特性的描述方面具有明显的优势，因为它是非侵入性的，提供相对较高的空间分辨率，并且适合重复研究，尽管它依赖于间接的神经血管耦合来提供信息。事实上，fMRI 以前曾被用于在人类和大鼠中描述听觉通路。然而，在老鼠中，听觉通路迄今为止仅使用锰增强 MRI 进行了映射。在这里，我们描述了一种专门设计的新设置，用于使用高场 fMRI 对小鼠听觉通路进行高分辨率映射。记录到了几乎整个听觉通路上的稳健且一致的血氧水平依赖（BOLD）反应，从耳蜗核（CN）到上橄榄复合体（SOC）、外侧丘系核（LL）、下丘（IC）和内侧膝状体（MGB）。相比之下，在这项研究中，在听觉皮层（AC）中没有观察到明显的 BOLD 反应。使用相干分析逐区域和逐像素绘制了不同的 BOLD 潜伏期，证明了不同听觉中心的平均 BOLD 时程不同。尽管由于统计功效不足，无法针对每个个体进行评估，但在汇总数据集中，在 IC、SOC 和 MGB 中确定了一定程度的音调拓扑。鉴于在可塑性研究、动物模型和光遗传学中老鼠模型的重要性，以及 fMRI 对特定线索的动态反应进行映射的潜力，这项对老鼠听觉通路的首次 fMRI 研究为未来研究体内广泛的听觉相关活动的纵向研究铺平了道路。
