In the mouse whisker system, the contribution of L6 corticothalamic cells (L6 CT) to cortical and thalamic processing of the whisker deflection direction was investigated. A genetically defined population of L6 CT cells project to infragranular GABAergic interneurons that hyperpolarize neurons in somatosensory barrel cortex (BC). Optogenetic activation of these neurons switched BC to an adapted mode in which excitatory cells lost their angular tuning. In contrast, however, this was not the case with a general activation of inhibitory interneurons via optogenetic activation of Gad2-expressing cells. The decrease in angular tuning, when L6 CT cells were activated, was due to changes in cortical inhibition, and not inherited from changes in the thalamic output. Furthermore, L6 CT driven cortical inhibition, but not the general activation of GABAergic interneurons, abolished adaptation to whisker responses. In the present study, evidence is presented that a subpopulation of L6 CT activates a specific circuit of GABAergic interneurons that will predispose neocortex toward processing of tactile information requiring multiple whisker touches, such as in a texture discrimination task.

中文翻译：

---

皮质丘脑第6层细胞的激活减少了小鼠桶状皮层的角度调整。

在小鼠晶须系统中，研究了L6皮质丘脑细胞（L6 CT）对晶须偏转方向的皮质和丘脑加工的贡献。遗传定义的L6 CT细胞群体投射到体下感官桶皮质（BC）中的神经元超极化的籽粒下GABA能中间神经元。这些神经元的光遗传激活将BC转换为一种适应性模式，其中兴奋性细胞失去了其角度调节。但是，相比之下，通过表达Gad2的细胞的光遗传激活来抑制中间神经元的一般激活却不是这种情况。当激活L6 CT细胞时，角度调谐的减少是由于皮质抑制作用的改变所致，而不是源自丘脑输出的改变。此外，L6 CT驱动皮质抑制，但不能完全激活GABA能中间神经元，从而消除了对晶须响应的适应性。在本研究中，有证据表明，L6 CT的一个亚群激活了GABA能性中间神经的特定电路，该电路将使新皮层倾向于处理需要多次须接触的触觉信息，例如在纹理识别任务中。