Department of Neurobiology, University of Chicago, Chicago, IL 60637.
Department of Neurobiology, University of Chicago, Chicago, IL 60637
Proc Natl Acad Sci U S A. 2017 Jul 25;114(30):E6212-E6221. doi: 10.1073/pnas.1703222114. Epub 2017 Jul 10.
Somatosensory information is thought to arrive in thalamus through two glutamatergic routes called the lemniscal and paralemniscal pathways via the ventral posterior medial (VPm) and posterior medial (POm) nuclei. Here we challenge the view that these pathways functionally represent parallel information routes. Using electrical stimulation and an optogenetic approach in brain slices from the mouse, we investigated the synaptic properties of the lemniscal and paralemniscal input to VPm and POm. Stimulation of the lemniscal pathway produced class 1, or "driver," responses in VPm relay cells, which is consistent with this being an information-bearing channel. However, stimulation of the paralemniscal pathway produced two distinct types of responses in POm relay cells: class 1 (driver) responses in 29% of the cells, and class 2, or "modulator," responses in the rest. Our data suggest that, unlike the lemniscal pathway, the paralemniscal one is not homogenous and that it is primarily modulatory. This finding requires major rethinking regarding the routes of somatosensory information to cortex and suggests that the paralemniscal route is chiefly involved in modulatory functions rather than simply being an information route parallel to the lemniscal channel.
躯体感觉信息被认为通过两条谷氨酸能途径到达丘脑，这两条途径分别称为索状和副索状通路，通过腹后内侧核（VPm）和后内侧核（POm）。在这里，我们质疑这些途径在功能上代表平行信息途径的观点。使用电刺激和在来自小鼠的脑切片中的光遗传学方法，我们研究了 VPm 和 POm 中索状和副索状输入的突触特性。索状通路的刺激在 VPm 中继细胞中产生了 1 类或“驱动”反应，这与该通路是信息承载通道一致。然而，副索状通路的刺激在 POm 中继细胞中产生了两种不同类型的反应：29%的细胞中产生了 1 类（驱动）反应，其余细胞中产生了 2 类或“调制”反应。我们的数据表明，与索状通路不同，副索状通路不是同质的，它主要是调制性的。这一发现需要对躯体感觉信息到皮层的途径进行重大重新思考，并表明副索状途径主要涉及调制功能，而不仅仅是作为与索状通道平行的信息途径。
