J Comp Neurol. 2014 Apr 15;522(6):1373-89. doi: 10.1002/cne.23491.
Here we studied the auditory thalamic input to the insular cortex using mice as a model system. An insular auditory field (IAF) has recently been identified in mice. By using retrograde neuronal tracing, we identified auditory thalamic neurons projecting to the IAF, primary auditory cortex (AI), and anterior auditory field (AAF). After mapping the IAF, AAF, and AI by using optical imaging, we injected a distinct fluorescent tracer into each of the three fields at frequency-matched locations. Tracer injection into the IAF resulted in retrogradely labeled cells localized ventromedially in the lemniscal division, i.e., the ventral subdivision of the medial geniculate body (MGv). Cells retrogradely labeled by injections into the AAF were primarily found in the medial half of the MGv, whereas those from AI injections were located in the lateral half, although some of these two subsets were intermingled within the MGv. Interestingly, retrogradely labeled cells projecting to the IAF showed virtually no overlap with those projecting to the AAF or the AI. Dual tracer injections into two sites responding to low- and high-frequency tones within each of the three auditory fields demonstrated topographic organizations in all three thalamocortical projections. These results indicate that the IAF receives thalamic input from the MGv in a topographic manner, and that the MGv–IAF projection is parallel to the MGv–AAF and MGv–AI projections.
在这里，我们使用小鼠作为模型系统研究了丘脑对脑岛皮质的听觉传入。最近在小鼠中发现了脑岛听觉区（IAF）。通过逆行神经元追踪，我们确定了投射到 IAF、初级听觉皮层（AI）和前听觉区（AAF）的听觉丘脑神经元。在通过光学成像映射 IAF、AAF 和 AI 后，我们将一个独特的荧光示踪剂注射到三个区域的每个频率匹配位置。将示踪剂注射到 IAF 中，导致标记细胞位于内侧核团腹侧亚区（MGv 的腹侧细分）中，即内侧膝状体核（MGv）的腹侧部分。注射到 AAF 中的细胞主要位于 MGv 的内侧半部分，而注射到 AI 中的细胞位于外侧半部分，尽管这两个亚群中的一些细胞在 MGv 内混合。有趣的是，投射到 IAF 的逆行标记细胞与投射到 AAF 或 AI 的细胞几乎没有重叠。在三个听觉场中的两个对低频和高频音有反应的部位进行双示踪剂注射，显示了所有三个丘脑皮质投射中的拓扑组织。这些结果表明 IAF 以拓扑方式接收来自 MGv 的丘脑输入，并且 MGv-IAF 投射与 MGv-AAF 和 MGv-AI 投射平行。
