IDENTIFICATION OF SYNAPTIC TERMINALS OF THALAMIC OR CORTICAL ORIGIN IN CONTACT WITH DISTINCT MEDIUM-SIZE SPINY NEURONS IN THE RAT NEOSTRIATUM
IDENTIFICATION OF SYNAPTIC TERMINALS OF THALAMIC OR CORTICAL ORIGIN IN CONTACT WITH DISTINCT MEDIUM-SIZE SPINY NEURONS IN THE RAT NEOSTRIATUM
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DOI：
10.1002/cne.902670402
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发表时间：
1988-01-22
影响因子：
2.5
通讯作者：
BOLAM, JP
中科院分区：
文献类型：
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作者：
DUBE, L;SMITH, AD;BOLAM, JP
为了确定纹状体中哪些类型的神经元接受皮质纹状体和丘脑纹状体纤维的直接突触输入，以及这些传入是否汇聚到单个纹状体神经元上，我们在光镜和电子显微镜水平上结合了轴突终末的双顺行标记和高尔基体染色。用辣根过氧化物酶和小麦胚凝集素(HRP-WGA)的结合物逆行运输的方法，确定了接受丘脑束旁核和躯体感觉皮质输入的新纹状体中央区域。在接受了躯体感觉皮质多次电解损伤并在束旁核不同部位注射HRP-WGA的大鼠身上，研究了新斜角区的同一区域。在发现顺行运输的HRP-WGA后，对新纹状体的这一部分进行单切面高尔基手术。金染色后取材，光镜和电子显微镜下观察12个高尔基体神经元。这些神经元中有10个是典型的非常密集的刺状中等大小的神经元，它们都被发现从退化的皮质纹状体突起接受树突上的不对称突触输入。然而，尽管在接受皮质输入的神经元的树突野中没有发现许多由HRP-WGA顺行标记的来自束旁核的终末，但来自丘脑的终末都没有与这些神经元进行突触接触。相反，所有研究的96个丘脑纹状体突触都是在与其他神经元的树突不对称的突触接触中发现的。从束旁核接受输入的两个这样的神经元是高尔基体染色的，似乎是中等大小的带刺神经元，但它们的刺密度低于典型的非常密集的带刺神经元。通过研究电解损毁或向丘脑束旁核注射凝集素普通菜豆-亮氨酸凝集素(PHA-L)后标记的突起，独立地证实了发自束旁核的丘脑纹状体神经元的靶标是树突：这些突触也被发现与新纹状体内的树突形成不对称的突触联系。结果表明，尽管来自躯体感觉皮质和束旁核的传入纤维汇聚在新纹状体的同一部位，但它们可能并不汇聚在同一刺状神经元上。来自新皮质的传入在密集刺状中型神经元的脊椎上形成突触，而来自束旁核神经元的终末与形态上截然不同的中型棘神经元的树突接触。来自这两个区域的输入的整合可能涉及这两种类型的棘神经元的局部轴突侧支。
In order to determine what types of neurons in the striatum receive direct synaptic input from corticostriatal and thalamostriatal fibres and whether these afferents converge on individual striatal neurons, double anterograde labelling of axon terminals was combined with Golgi impregnation at both the light and electron microscopic levels. The area of the central neostriatum that receives input from both the parafascicular nucleus of the thalamus and the somatosensory cortex was identified by retrograde transport of a conjugate of horseradish peroxidase and wheat germ aglutinin (HRP-WGA). The same region of the neostraitum was studied in rats that had received multiple electrolytic lesions in the somatosensory cortex and also an injection of HRP-WGA in different parts of the parafascicular nucleus. Sections of this part of the neostriatum were impregnated by the single-section Golgi procedure after revealing anterogradely transported HRP-WGA. Twelve Golgi-impregnated spiny neurons were recovered and examined in the light and electron microscope after gold-toning. Ten of these neurons were typical very densely spiny medium-size neurons and they were all found to receive asymmetric synaptic input on dendritic spines from degenerating corticostriatal boutons. However, even though numerous boutons labelled anterogradely by HRP-WGA from the parafascicular nucleus not found within the dendritic fields of neurons that received cortical input, none of the terminals from the thalamus made synaptic contact with these neurons. Instead, all 96 thalamostriatal boutons studied were found in asymmetric synaptic contact with dendritic shafts of other neurons. Two such neurons that received input from the parafascicular nucleus were Golgi-impregnated and appeared to be medium-size spiny neurons, but they had a lower density of spines than the typical very densely spiny neurons. An independent confirmation that the targets of thalamostriatal neurons originating in the parafascicular nucleus are dendritic shafts was provided by studying the boutons labelled following electrolytic lesioning or injection of the lectin Phaseolus vulgaris-leucoagglutinin (PHA-L) into this nucleus: these boutons were also found to form asymmetric synaptic contacts with dendritic shafts within the neostriatum. It is concluded that although afferents from the somatosensory cortex and from the parafascicular nucleus converge upon the same part of the neostriatum, they probably do not converge upon the same spiny neurons. The afferents from the neocortex form synapses on the spines of densely spiny medium-size neurons, whereas terminals orginating from neurons in the parafascicular nucleus are in synaptic contact with the dendritic shafts of what appears to be a morphologically distinct type of medium-size spiny neuron. The integration of the inputs from these two areas probably involves the local axon collaterals of these two types of spiny neuron.