Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America.
PLoS Biol. 2011 Jan 4;9(1):e1000572. doi: 10.1371/journal.pbio.1000572.
Rodents move their whiskers to locate and identify objects. Cortical areas involved in vibrissal somatosensation and sensorimotor integration include the vibrissal area of the primary motor cortex (vM1), primary somatosensory cortex (vS1; barrel cortex), and secondary somatosensory cortex (S2). We mapped local excitatory pathways in each area across all cortical layers using glutamate uncaging and laser scanning photostimulation. We analyzed these maps to derive laminar connectivity matrices describing the average strengths of pathways between individual neurons in different layers and between entire cortical layers. In vM1, the strongest projection was L2/3→L5. In vS1, strong projections were L2/3→L5 and L4→L3. L6 input and output were weak in both areas. In S2, L2/3→L5 exceeded the strength of the ascending L4→L3 projection, and local input to L6 was prominent. The most conserved pathways were L2/3→L5, and the most variable were L4→L2/3 and pathways involving L6. Local excitatory circuits in different cortical areas are organized around a prominent descending pathway from L2/3→L5, suggesting that sensory cortices are elaborations on a basic motor cortex-like plan.
啮齿动物通过移动胡须来定位和识别物体。涉及触须体感和感觉运动整合的皮层区域包括初级运动皮层（vM1）、初级体感皮层（vS1；桶状皮层）和次级体感皮层（S2）的触须区域。我们使用谷氨酸离笼和激光扫描光刺激，在所有皮层层中绘制了每个区域的局部兴奋性通路。我们分析了这些图谱，得出了描述不同层之间和整个皮层层之间个体神经元之间平均路径强度的分层连接矩阵。在 vM1 中，最强的投射是 L2/3→L5。在 vS1 中，强烈的投射是 L2/3→L5 和 L4→L3。在两个区域中，L6 的输入和输出都很弱。在 S2 中，L2/3→L5 的强度超过了上行 L4→L3 投射的强度，并且 L6 的局部输入很明显。最保守的通路是 L2/3→L5，最可变的是 L4→L2/3 和涉及 L6 的通路。不同皮层区域的局部兴奋性回路围绕着从 L2/3→L5 的突出下行通路进行组织，这表明感觉皮层是对基本运动皮层样计划的精细扩展。
