Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore 20 Penn St, HSF-2, 21201 MD, Baltimore, United States.
Department of Neuroscience, John Hopkins School of Medicine, 855 N. Wolfe Street, Rangos 295, Baltimore, MD 21205, United States.
Neuroscience. 2022 Jul 1;494:140-151. doi: 10.1016/j.neuroscience.2022.05.018. Epub 2022 May 20.
In Robo3cKO mouse brain, rhombomere 3-derived trigeminal principal nucleus (PrV) neurons project bilaterally to the somatosensory thalamus. As a consequence, whisker-specific neural modules (barreloids and barrels) representing whiskers on both sides of the face develop in the sensory thalamus and the primary somatosensory cortex. We examined the morphological complexity of layer 4 barrel cells, their postsynaptic partners in layer 3, and functional specificity of layer 3 pyramidal cells. Layer 4 spiny stellate cells form much smaller barrels and their dendritic fields are more focalized and less complex compared to controls, while layer 3 pyramidal cells did not show notable differences. Using in vivo 2-photon imaging of a genetically encoded fluorescent [Ca] sensor, we visualized neural activity in the normal and Robo3cKO barrel cortex in response to ipsi- and contralateral single whisker stimulation. Layer 3 neurons in control animals responded only to their contralateral whiskers, while in the mutant cortex layer 3 pyramidal neurons showed both ipsi- and contralateral whisker responses. These results indicate that bilateral whisker map inputs stimulate different but neighboring groups of layer 3 neurons which normally relay contralateral whisker-specific information to other cortical areas.
在 Robo3cKO 小鼠大脑中，菱脑 3 区衍生的三叉神经主核（PrV）神经元向双侧投射到躯体感觉丘脑。结果，代表面部两侧胡须的特定胡须神经模块（barreloids 和 barrels）在感觉丘脑和初级躯体感觉皮层中发育。我们检查了第 4 层棘状星形细胞的形态复杂性、它们在第 3 层中的突触后伙伴以及第 3 层金字塔形细胞的功能特异性。与对照组相比，第 4 层多刺星状细胞形成的桶更小，其树突场更集中且不那么复杂，而第 3 层金字塔形细胞没有显示出明显的差异。使用体内遗传编码荧光[Ca]传感器的 2 光子成像，我们可视化了正常和 Robo3cKO 桶状皮层对同侧和对侧单个胡须刺激的神经活动。在对照动物中，第 3 层神经元仅对其对侧胡须有反应，而在突变皮层中，第 3 层金字塔形神经元显示同侧和对侧胡须反应。这些结果表明，双侧胡须图输入刺激不同但相邻的第 3 层神经元群，这些神经元通常将对侧胡须特异性信息传递到其他皮质区域。
