Shiramatsu Tomoyo Isoguchi, Takahashi Kazusa, Noda Takahiro, Kanzaki Ryohei, Nakahara Haruka, Takahashi Hirokazu
Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan; Graduate School of Information Science and Technology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Neuroscience. 2016 Sep 22;332:38-52. doi: 10.1016/j.neuroscience.2016.06.024. Epub 2016 Jun 18.
The rat has long been considered an important model system for studying neural mechanisms of auditory perception and learning, and particularly mechanisms involving auditory thalamo-cortical processing. However, the functional topography of the auditory thalamus, or medial geniculate body (MGB) has not yet been fully characterized in the rat, and the anatomically-defined features of field-specific, layer-specific and tonotopic thalamo-cortical projections have never been confirmed electrophysiologically. In the present study, we have established a novel technique for recording simultaneously from a surface microelectrode array on the auditory cortex, and a depth electrode array across auditory cortical layers and within the MGB, and characterized the rat MGB and thalamo-cortical projections under isoflurane anesthesia. We revealed that the ventral division of the MGB (MGv) exhibited a low-high-low CF gradient and long-short-long latency gradient along the dorsolateral-to-ventromedial axis, suggesting that the rat MGv is divided into two subdivisions. We also demonstrated that microstimulation in the MGv elicited cortical activation in layer-specific, region-specific and tonotopically organized manners. To our knowledge, the present study has provided the first and most compelling electrophysiological confirmation of the anatomical organization of the primary thalamo-cortical pathway in the rat, setting the groundwork for further investigation.
长期以来，大鼠一直被视为研究听觉感知和学习神经机制的重要模型系统，尤其是涉及听觉丘脑 - 皮质处理的机制。然而，大鼠听觉丘脑或内侧膝状体（MGB）的功能地形图尚未完全明确，并且场特异性、层特异性和音调拓扑丘脑 - 皮质投射的解剖学定义特征从未通过电生理学得到证实。在本研究中，我们建立了一种新技术，可同时从听觉皮层的表面微电极阵列以及跨越听觉皮层各层和MGB内部的深度电极阵列进行记录，并在异氟烷麻醉下对大鼠MGB和丘脑 - 皮质投射进行了表征。我们发现，MGB的腹侧部分（MGv）沿背外侧到腹内侧轴呈现出低 - 高 - 低的CF梯度和长 - 短 - 长的潜伏期梯度，这表明大鼠MGv可分为两个亚区。我们还证明，在MGv中进行微刺激会以层特异性、区域特异性和音调拓扑组织的方式引起皮层激活。据我们所知，本研究首次提供了最令人信服的大鼠初级丘脑 - 皮质通路解剖组织的电生理学证实，为进一步研究奠定了基础。
