Cusick C G, Steindler D A, Kaas J H
Somatosens Res. 1985;3(1):1-31. doi: 10.3109/07367228509144574.
Experiments were performed to determine whether thalamic neurons send collaterals to more than one subdivision of postcentral somatosensory cortex, and to evaluate the fidelity of somatotopic connections between cortical representations of the body surface. After microelectrode recordings identified the locations of the representations of the fingertips along the border of area 3b with area 3a and along the border of area 1 with area 2, one tracer, tritiated N-acetyl wheatgerm agglutinin ([3H]WGA), was injected into the rostral representation at the 3a-3b border, and another, wheatgerm agglutinin conjugated to horseradish peroxidase (WGA:HRP), was injected into the caudal representation at the 1-2 border. The results indicate that three thalamic regions are interconnected with both border zones. Regions of overlapping retrograde and anterograde label included the ventromedial portion of the lateral division of the ventroposterior nucleus (VPL), which is known to represent the digits; the medial extent of a dorsal capping zone of VPL that we term the ventroposterior superior nucleus (VPS); and the anterior pulvinar (Pa). Cells labeled with one or the other tracer, as well as cells labeled with both tracers, were found in VPL, VPS, and Pa. Our procedures necessarily underestimated the numbers of cells projecting to both rostral and caudal injection zones, but at least 15-20% of VPL and 20-40% of VPS neurons that were autoradiographically labeled appeared to have such collaterals. While only a few cells in Pa were autoradiographically labeled from injections at the 3a-3b border, the presence of several double-labeled cells suggests that at least some Pa neurons project to both injected zones. By relating the present results to those from studies where connections were determined for single architectonic fields, we conclude that many neurons in VP project to both areas 3b and 1, and that many neurons in VPS project to both areas 3a and 2. In addition, both areas 3a and 2 appear to have interconnections with Pa. Connections of Pa with area 2 have only recently been reported (Pons and Kaas, in press), and connections of Pa with area 3a have not been described. The results imply that, in part, the same information from cutaneous receptors is relayed to areas 3b and 1, and the same information from deep receptors is relayed to areas 3a and 2.(ABSTRACT TRUNCATED AT 400 WORDS)
进行了实验以确定丘脑神经元是否向中央后体感皮层的多个亚区发送侧支，并评估体表皮层表征之间躯体定位连接的保真度。在通过微电极记录确定了沿着3b区与3a区边界以及1区与2区边界的指尖表征位置后，将一种示踪剂，即氚标记的N-乙酰小麦胚芽凝集素（[3H]WGA），注入3a - 3b边界处的嘴侧表征区，另一种示踪剂，即与辣根过氧化物酶结合的小麦胚芽凝集素（WGA:HRP），注入1 - 2边界处的尾侧表征区。结果表明，三个丘脑区域与两个边界区相互连接。逆行和顺行标记重叠的区域包括腹后外侧核（VPL）外侧部的腹内侧部分，已知该部分代表手指；我们将VPL背侧覆盖区的内侧范围称为腹后上核（VPS）；以及前丘脑枕（Pa）。在VPL、VPS和Pa中发现了用一种或另一种示踪剂标记的细胞，以及用两种示踪剂都标记的细胞。我们的操作必然低估了投射到嘴侧和尾侧注射区的细胞数量，但通过放射自显影标记的VPL神经元中至少15 - 20%以及VPS神经元中20 - 40%似乎有这样的侧支。虽然从3a - 3b边界处注射后，Pa中只有少数细胞通过放射自显影被标记，但几个双标记细胞的存在表明至少一些Pa神经元投射到两个注射区。通过将当前结果与那些确定单个结构域连接的研究结果相关联，我们得出结论，VP中的许多神经元投射到3b区和1区，VPS中的许多神经元投射到3a区和2区。此外，3a区和2区似乎都与Pa有相互连接。Pa与2区的连接最近才被报道（庞斯和卡斯，即将发表），而Pa与3a区的连接尚未被描述。结果表明，部分来自皮肤感受器的相同信息被传递到3b区和1区，来自深部感受器的相同信息被传递到3a区和2区。（摘要截断于400字）
