Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200031 Shanghai, China.
State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 100101 Beijing, China.
Proc Natl Acad Sci U S A. 2018 May 29;115(22):E5174-E5182. doi: 10.1073/pnas.1719711115. Epub 2018 May 14.
In the primary visual cortex (V1) of many mammalian species, neurons are spatially organized according to their preferred orientation into a highly ordered map. However, whether and how the various presynaptic inputs to V1 neurons are organized relative to the neuronal orientation map remain unclear. To address this issue, we constructed genetically encoded calcium indicators targeting axon boutons in two colors and used them to map the organization of axon boutons of V1 intrinsic and V2-V1 feedback projections in tree shrews. Both connections are spatially organized into maps according to the preferred orientations of axon boutons. Dual-color calcium imaging showed that V1 intrinsic inputs are precisely aligned to the orientation map of V1 cell bodies, while the V2-V1 feedback projections are aligned to the V1 map with less accuracy. Nonselective integration of intrinsic presynaptic inputs around the dendritic tree is sufficient to reproduce cell body orientation preference. These results indicate that a precisely aligned map of intrinsic inputs could reinforce the neuronal map in V1, a principle that may be prevalent for brain areas with function maps.
在许多哺乳动物的初级视觉皮层（V1）中，神经元根据其最佳方向在高度有序的图谱中进行空间组织。然而，V1 神经元的各种前突触输入相对于神经元方向图是否以及如何组织尚不清楚。为了解决这个问题，我们构建了两种颜色的靶向轴突末梢的基因编码钙指示剂，并使用它们来绘制树鼩 V1 内在和 V2-V1 反馈投射的轴突末梢的组织图。这两种连接都根据轴突末梢的最佳方向进行空间组织成图谱。双色钙成像显示，V1 内在输入与 V1 细胞体的方向图谱精确对齐，而 V2-V1 反馈投射与 V1 图谱的对齐精度较低。树突上内在突触输入的非选择性整合足以再现细胞体方向偏好。这些结果表明，内在输入的精确对齐图谱可以增强 V1 中的神经元图谱，这一原则可能在具有功能图谱的大脑区域中普遍存在。
