Department of Systems Neuroscience, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany.
Front Neural Circuits. 2019 Nov 1;13:67. doi: 10.3389/fncir.2019.00067. eCollection 2019.
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.
在老鼠胡须系统中，研究了 L6 皮层丘脑细胞（L6 CT）对胡须偏转方向的皮层和丘脑处理的贡献。L6 CT 细胞的一个遗传定义群体投射到 GABA 能中间神经元，这些中间神经元使体感皮层（BC）的神经元超极化。这些神经元的光遗传学激活将 BC 切换到适应模式，其中兴奋性细胞失去了角度调谐。然而，通过光遗传学激活 Gad2 表达细胞来普遍激活抑制性中间神经元，情况并非如此。当 L6 CT 细胞被激活时，角度调谐的降低是由于皮层抑制的变化，而不是来自丘脑输出的变化。此外，L6 CT 驱动的皮层抑制，而不是 GABA 能中间神经元的普遍激活，消除了对胡须反应的适应。在本研究中，提出了证据表明，L6 CT 的一个亚群激活了特定的 GABA 能中间神经元回路，这将使新皮层倾向于处理需要多次胡须触摸的触觉信息，例如在纹理辨别任务中。
