Nakamura Hisashi, Ohta Keisuke
Division of Microscopic and Developmental Anatomy, Department of Anatomy, Kurume University School of Medicine, Kurume, Japan.
Advanced Imaging Research Center, Kurume University School of Medicine, Kurume, Japan.
Front Neuroanat. 2024 Aug 7;18:1430636. doi: 10.3389/fnana.2024.1430636. eCollection 2024.
The rat lateral posterior thalamic nucleus (LP) is composed of the rostromedial (LPrm), lateral (LPl), and caudomedial parts, with LPrm and LPl being areas involved in information processing within the visual cortex. Nevertheless, the specific differences in the subcortical projections to the LPrm and LPl remain elusive. In this study, we aimed to reveal the subcortical regions that project axon fibers to the LPl and LPrm using a retrograde neural tracer, Fluorogold (FG). After FG injection into the LPrm or LPl, the area was visualized immunohistochemically. Retrogradely labeled neurons from the LPrm were distributed in the retina and the region from the diencephalon to the medulla oblongata. Diencephalic labeling was found in the reticular thalamic nucleus (Rt), zona incerta (ZI), ventral lateral geniculate nucleus (LGv), intergeniculate leaflet (IGL), and hypothalamus. In the midbrain, prominent labeling was found in the periaqueductal gray (PAG) and deep layers of the superior colliculus. Additionally, retrograde labeling was observed in the cerebellar and trigeminal nuclei. When injected into the LPl, several cell bodies were labeled in the visual-related regions, including the retina, LGv, IGL, and olivary pretectal nucleus (OPT), as well as in the Rt and anterior pretectal nucleus (APT). Less labeling was found in the cerebellum and medulla oblongata. When the number of retrogradely labeled neurons from the LPrm or LPl was compared as a percentage of total subcortical labeling, a larger percentage of subcortical inputs to the LPl included projections from the APT, OPT, and Rt, whereas a large proportion of subcortical inputs to the LPrm originated from the ZI, reticular formation, and PAG. These results suggest that LPrm not only has visual but also multiple sensory-and motor-related functions, whereas the LPl takes part in a more visual-specific role. This study enhances our understanding of subcortical neural circuits in the thalamus and may contribute to our exploration of the mechanisms and disorders related to sensory perception and sensory-motor integration.
大鼠丘脑外侧后核（LP）由吻内侧部（LPrm）、外侧部（LPl）和尾内侧部组成，其中LPrm和LPl是参与视觉皮层信息处理的区域。然而，向LPrm和LPl的皮质下投射的具体差异仍不清楚。在本研究中，我们旨在使用逆行神经示踪剂荧光金（FG）揭示向LPl和LPrm投射轴突纤维的皮质下区域。将FG注入LPrm或LPl后，通过免疫组织化学观察该区域。来自LPrm的逆行标记神经元分布在视网膜以及从间脑到延髓的区域。在丘脑网状核（Rt）、未定带（ZI）、腹外侧膝状核（LGv）、间膝小叶（IGL）和下丘脑发现了间脑标记。在中脑，导水管周围灰质（PAG）和上丘深层有明显标记。此外，在小脑核和三叉神经核中观察到逆行标记。当注入LPl时，在包括视网膜、LGv、IGL和橄榄前顶盖核（OPT）以及Rt和前顶盖前核（APT）在内的视觉相关区域标记了几个细胞体。在小脑和延髓中发现的标记较少。当将来自LPrm或LPl的逆行标记神经元数量作为皮质下总标记的百分比进行比较时，向LPl的皮质下输入中较大比例包括来自APT、OPT和Rt的投射，而向LPrm的皮质下输入很大一部分起源于ZI、网状结构和PAG。这些结果表明，LPrm不仅具有视觉功能，还具有多种与感觉和运动相关的功能，而LPl则发挥更具视觉特异性的作用。本研究增进了我们对丘脑皮质下神经回路的理解，并可能有助于我们探索与感觉知觉和感觉运动整合相关的机制和障碍。
