Bernardo K L, McCasland J S, Woolsey T A, Strominger R N
Department of Neurology and Neurological Surgery, Washington University School of Medicine, St. Louis, Missouri 63110.
J Comp Neurol. 1990 Jan 8;291(2):231-55. doi: 10.1002/cne.902910207.
Focal injections of horseradish peroxidase (HRP) in dimethylsulfoxide (DMSO) were targeted into mouse somatosensory cortex, in vitro, with a template. Injections were made at different depths and in different locations in the whisker-barrel-defined somatosensory map in order to determine quantitative connectivity patterns within and between barrel-defined cortical columns. Cortices were sectioned in a plane parallel to the pia at 75 microns. Data were collected directly from microscope slides by computer. Data are presented as: 1) Plots of computer-mapped HRP reaction product density in neurons and cell locations for each section in relation to barrel boundaries; 2) histograms of label in cortical layers related to individual barrel-defined columns; 3) polar plots of relative amounts of label within individual barrel columns in sections through each barrel column; 4) vectors which represent HRP reaction product density as a function of direction and distance from the injection site; 5) statistical analysis of the shape of the label distribution pattern in the plane of the cortex as a function of injection site depth; and 6) probability of labeling of any other barrel column given a labeled barrel column. The principal findings are: 1) The pattern of label distribution, after an injection directly above or directly below an individual barrel, is hour-glass shaped with the waist of the hour-glass in layer IV. 2) Connections within barrel cortex are asymmetrical. Barrel-related columns within a row are more strongly interconnected than those in different rows. 3) Connections of the small barrels associated with whiskers on the upper lip are strongest with other small barrels, but strong connections also exist between these small barrels and the larger barrels. 4) The pattern of intracortical connections in SII is not asymmetrical; interlaminar connections in SII are fundamentally different from those in barrel cortex. 5) Quantitative intracortical projection patterns are highly consistent with functional data on intracortical processing of whisker information. As such, the quantitative data clearly indicate the spatial extent and relative magnitude of populations of neurons involved in intracortical processing of sensory information. The spatial arrangements of these intracortical connections, in conjunction with known developmental events, make it highly likely that the distribution of intracortical axons in mouse barrel cortex is sculpted in part by experience.
在体外，利用模板将溶于二甲基亚砜（DMSO）的辣根过氧化物酶（HRP）局灶性注射到小鼠体感皮层。在晶须桶状体感图谱的不同深度和不同位置进行注射，以确定桶状皮层柱内和柱间的定量连接模式。将皮层在平行于软脑膜的平面上切成75微米厚的切片。数据通过计算机直接从显微镜载玻片上收集。数据呈现为：1）每个切片中计算机映射的HRP反应产物密度在神经元和细胞位置相对于桶状边界的图；2）与各个桶状定义柱相关的皮层各层中标记的直方图；3）通过每个桶状柱的切片中各个桶状柱内标记相对量的极坐标图；4）表示HRP反应产物密度作为距注射部位方向和距离函数的向量；5）作为注射部位深度函数的皮层平面中标记分布模式形状的统计分析；6）给定一个标记的桶状柱时任何其他桶状柱被标记的概率。主要发现如下：1）在单个桶状结构正上方或正下方注射后，标记分布模式呈沙漏形，沙漏的腰部位于IV层。2）桶状皮层内的连接是不对称的。同一排内与桶状相关的柱之间的相互连接比不同排之间的更强。3）与上唇晶须相关的小桶状结构与其他小桶状结构的连接最强，但这些小桶状结构与较大桶状结构之间也存在强连接。4）第二体感区（SII）内的皮层内连接模式不是不对称的；SII内的层间连接与桶状皮层的层间连接根本不同。5）皮层内定量投射模式与晶须信息皮层内处理的功能数据高度一致。因此，定量数据清楚地表明了参与感觉信息皮层内处理神经元群体的空间范围和相对大小。这些皮层内连接的空间排列，结合已知的发育事件，使得小鼠桶状皮层内皮层轴突的分布很可能部分是由经验塑造的。
