SPINOTHALAMIC AND SPINOHYPOTHALAMIC TRACT NEURONS IN THE CERVICAL ENLARGEMENT OF RATS .1. LOCATIONS OF ANTIDROMICALLY IDENTIFIED AXONS IN THE THALAMUS AND HYPOTHALAMUS
SPINOTHALAMIC AND SPINOHYPOTHALAMIC TRACT NEURONS IN THE CERVICAL ENLARGEMENT OF RATS .1. LOCATIONS OF ANTIDROMICALLY IDENTIFIED AXONS IN THE THALAMUS AND HYPOTHALAMUS
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DOI：
10.1152/jn.1994.71.3.959
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发表时间：
1994-03-01
影响因子：
2.5
通讯作者：
GIESLER, GJ
中科院分区：
文献类型：
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作者：
DADO, RJ;KATTER, JT;GIESLER, GJ
1. 尿素脲麻醉后，77个大鼠颈部增大神经元在对侧后丘脑小于或等于30 μ A的电流下被初始反行激活。这些实验的目的之一是确定间脑内脊髓轴突的生理特征的过程。因此，在38例病例中，在多个前后平面上对间脑的中外侧范围进行了额外的反角定位。71个神经元恢复了记录位点的电解损伤。31个位于浅背角（SDH）；39例位于固有核或深背角外侧网状区，1例位于腹角。38个神经元中有8个（21%）被测试为更多的前投射，只有当来自对侧后丘脑的电流小于或等于30 μ A时，才能被反向激活。这样的神经元被称为脊髓丘脑束（STT）神经元。标志着最低反侧激活阈值点的病变位于后丘脑组（Po）或附近。在更前的水平上，反向激活需要相当高的电流，否则不可能以高达500 μ a的电流激活神经元。其中四个神经元具有生理特征，每个神经元都优先响应有害的机械刺激（宽动态范围，WDR）。被测试的三个神经元中的每一个都对有害的热刺激有反应。这些发现证实了解剖研究表明，许多STT轴突终止于Po，并表明这些起源于颈部扩大的轴突携带来自上肢的伤害性输入。在15例中，电极渗透系统地遍及对侧腹底复合体（VbC）的大部分。在17例中，穿透整个对侧板内核，包括中央外侧核（CL）。令人惊讶的是，只有一个被检查的轴突被来自CL的低电流和一个来自VbC的低电流反向激活，尽管已知这两个核都接受来自STT.5的大量输入。许多轴突（38个测试中的27个，占71%）最初从对侧后丘脑被反向激活，也可以在低电流（小于或等于30 μ A）下被反向激活，并且在位于对侧下丘脑前部的位置以增加的潜伏期被反向激活。这种神经元被称为脊髓丘脑束/脊髓下丘脑束（STT/SHT）神经元。下丘脑反视激活最低阈值的病变集中在视上节、视束和视交叉尾侧或其附近。测定了其中20个神经元对无害和有害机械刺激的反应。其中11个为WDR神经元。其余9个被归类为高阈值（HT）神经元。17例中有14例（82%）对毒辣有反应。这些结果证实了我们早期的研究，并表明颈部扩大中的许多伤害性神经元同时投射到丘脑和下丘脑。产生与最低阈值点之间的距离，以确定电流在下丘脑内的有效传播。30亩A的最大有效传播电流与400亩A相似（13亩/亩A）。最低阈值处的反激激活的平均阈值与15 μ A相似，因此从最低阈值处扩散的有效电流可能为
1. Seventy-seven neurons in the cervical enlargement of rats anesthetized with urethan were initially antidromically activated using currents less than or equal to 30 mu A from the contralateral posterior thalamus. A goal of these experiments was to determine the course of physiologically characterized spinal axons within the diencephalon. Therefore, in 38 cases, additional antidromic mapping was done throughout the mediolateral extent of the diencephalon at multiple anterior-posterior planes.2. Electrolytic lesions marking the recording sites were recovered for 71 neurons. Thirty-one were located in the superficial dorsal horn (SDH); 39 were in nucleus proprius or the lateral reticulated area of the deep dorsal horn (DDH), and one was in the ventral horn.3. Eight of 38 (21%) neurons that were tested for more anterior projections could only be antidromically activated with currents less than or equal to 30 mu A from sites in the contralateral posterior thalamus. Such neurons are referred to as spinothalamic tract (STT) neurons. Lesions marking the lowest threshold points for antidromic activation were located in or near the posterior thalamic group (Po). At more anterior levels, considerably higher currents were required for antidromic activation or it was not possible to activate the neurons with currents up to 500 mu A. Four of these neurons were physiologically characterized and each responded preferentially to noxious mechanical stimuli (wide dynamic range, WDR). Each of the three neurons that were tested responded to noxious heat stimuli. These findings confirm anatomic studies that have shown that a number of STT axons terminate in Po and suggest that such axons that originate in the cervical enlargement carry nociceptive input from the upper extremity.4. In 15 cases, electrode penetrations were made systematically throughout much of the contralateral ventrobasal complex (VbC). In 17 cases, penetrations were made throughout the intralaminar nuclei contralaterally, including the central lateral nucleus (CL). Surprisingly, only one of the examined axons was antidromically activated with low currents from CL and one from VbC, although both of these nuclei are known to receive sizeable inputs from the STT.5. Many of the axons (27 of the 38 tested, 71%) that were initially antidromically activated from the contralateral posterior thalamus could also be antidromically activated with low currents (less than or equal to 30 mu A) and at increased latencies from sites located anteriorly in the contralateral hypothalamus. Such neurons are referred to as spinothalamic tract/spinohypothalamic tract (STT/SHT) neurons. Lesions marking the lowest threshold points for antidromic activation in the hypothalamus were concentrated in or near the supraoptic decussation, optic tract, and caudal part of the optic chiasm. Responses of 20 of these neurons to innocuous and noxious mechanical stimuli were determined. Eleven were classified as WDR neurons. The other nine were classified as high threshold (HT) neurons. Fourteen of 17 (82%) responded to noxious heat. These results confirm our earlier studies and demonstrate that many nociceptive neurons in the cervical enlargement project to both the thalamus and hypothalamus. distances from the lowest threshold points were generated to determine the effective spread of current within the hypothalamus. The maximum effective spread of currents of 30 mu A was similar to 400 mu m (13 mu m/mu A). The mean threshold for antidromic activation at the lowest threshold points was similar to 15 mu A, and thus it appears that the effective current spread away from the lowest threshold points was probably