Difference of relay modes in synaptic organization of the somatic and visceral thalamic nuclei.

通过光镜和电子显微镜对丘脑躯体核和内脏核进行观察，了解其突触组织的特点。我们选择腹侧外侧核（VL）和腹前核（VA）作为运动核，内侧膝状核（MGN）作为感觉核，室旁丘脑核（PVT）作为内脏核。在VL中，连续超薄切片的三维重建显示，小脑末梢（clr）主要在丘脑皮质投射神经元（TCNs）的初级和次级树突上建立突触接触，而皮质末梢在远端树突上建立突触。固有神经元的突触前树突（psd）和来源不明的轴突末端（Ps）在树突和神经元体的各个阶上形成突触。我们还分析了由CLR、TCN和PSD的树突形成的突触复合体（突触三联体）。丘脑网状核（TRN）的末端属于P，独立于突触三联体。在VA中，髓核内终末（ELPs）主要与中脑神经网络的躯体和初级树突进行突触接触。ELP、TCN树突和PSD之间存在突触三联性。由于ELP在本质上具有抑制作用，PSD可能对TCN起去抑制作用。VA的TRN末端经常显示序列突触，它们与elp或具有圆形囊泡的末端突触相连。我们通过研究皮质-皮质连接来了解听觉信息加工的形态学基础。在这项研究中，我们精确地检查了听觉相关皮层区域和中脑核亚核之间的关系。关于PVT，我们证明了作为排尿中枢的巴林顿核中的神经元通过轴突侧枝向脊髓和PVT发送轴突。我们还观察到许多PVT神经元通过侧枝向边缘皮层和伏隔核发出轴突。

We observed light and electron microscopically somatic and visceral thalamic nuclei to know their characteristics of the synaptic organization. Wechose the ventral lateral (VL) and ventral anterior (VA) nuclei as the motor, the medial geniculate nucleus (MGN) as the sensory and the paraventricular thalamic nucleus (PVT) as the visceral nuclei.In the VL,three-dimensional reconstruction from serial ultrathin sections revealed that cerebellar terminals (CLRs) predominantly made synaptic contacts on primary and secondary dendrites of thalamocortical projection neurons (TCNs), whereas, cortical terminals made synapses on distal dendrites. Presynaptic dendrites (PSDs) of intrinsic neurons and axon terminals of unidentified origins (Ps) made synapses on every order of dendrites and neuronal somata. The synaptic complex (synaptic triad), formed by the CLR,dendrites of the TCN and the PSD was also analyzed. Terminals from the thalamic reticular nucleus (TRN), which belong to P were located independently from the synaptic triad. In the VA,entopeduncular terminals (ELPs) mainly made synaptic contacts with somata and primary dendrites of TCNs. The synaptic triad among the ELP,TCN dendrites and PSD was also observed. Because the ELP is inhibitory in nature, the PSD may play a role of disinhibition against the TCN.TRN terminals in the VA often showed serial synapses in which they were posynaptic to ELPs or terminals with round vesicles.We studied the corticocortical connections to know the morphological bases of auditory information processing. During this study we examined the relationship between auditory related cortical areas and the subnuclei of the MGN precisely.About the PVT,we proved that neurons in the Barrington's nucleus which is known as the micturition center sent axons to both the spinal cord and the PVT by axon collaterals. We also observed that many PVT neurons gave off axons to both the limbic cortex and nucleus accumbens by collaterals.