Landing B H, Shankle W R, Hara J
Department of Pathology and of Pediatrics, University of Southern California School of Medicine, USA.
Acta Paediatr Jpn. 1998 Dec;40(6):530-43. doi: 10.1111/j.1442-200x.1998.tb01986.x.
This study examines JL Conel's data on neuron numbers in 35 human cortical areas for eight age points from 0 (birth) to 72 months, to analyze cortical columns, the presumed functional units of the cortex. For each cortical area at each age point, cortical surface divided by the square root of the area's neuron number gives cross-sectional areas with radii ranging from 180 microns at birth to 250 microns at 72 months. For the prefrontal cortex at birth and 48 months, these radii are approximately 2.10 and 1.19 times the longest radial basal dendrites, suggesting similar dimensions between these two measures of column radius. The logarithm of neuron number per cortical area and age point was examined in relation to the Weber-Fechner law governing the relationship between stimulus intensity and perception. A mechanism for this law consistent with the cortical model of Douglas et al. illustrates the importance of local circuit neurons. The cross-sectional areas of hexagonal columns for prefrontal cortex, using as radius, the longest radial extent of layer 5 pyramidal neuron basal dendrites, ranging from 0.013 mm2 at birth to 0.064 mm2 at 48 months, suggests that functional cortical columns increase cross-sectional area during development. These cross-sectional areas are 55-100-fold larger at birth, and 229-277-fold larger at 48 months, than those computed from somal width in prefrontal, layer 5 pyramidal neurons. Comparison of radial extent of pyramidal basal dendrites to their soma-to-soma distances shows that layer 3 pyramidal basal dendrites reach 1.5 and 4.0 other pyramidal neurons at 15 and 60 months, respectively, while layer 5, extra-large pyramidal basal dendrites reach 1.14 and 1.72 other such neurons at birth and 48 months, respectively. If such a relationship holds for other cortical areas, then the Conel data can be used to estimate basal dendrite extent, for which there currently is a paucity of data.
本研究考察了JL·科内尔关于35个人类皮质区域在从0（出生）到72个月的8个年龄点的神经元数量的数据，以分析皮质柱，即假定的皮质功能单位。对于每个年龄点的每个皮质区域，皮质表面积除以该区域神经元数量的平方根，得到的横截面积半径范围从出生时的180微米到72个月时的250微米。对于出生时和48个月时的前额叶皮质，这些半径分别约为最长径向基底树突的2.10倍和1.19倍，这表明这两种皮质柱半径测量方法之间的尺寸相似。研究了每个皮质区域和年龄点的神经元数量对数与支配刺激强度和感知之间关系的韦伯 - 费希纳定律的相关性。与道格拉斯等人的皮质模型一致的该定律机制说明了局部回路神经元的重要性。以前额叶皮质第5层锥体神经元基底树突的最长径向范围作为半径计算的六边形柱的横截面积，从出生时的0.013平方毫米到48个月时的0.064平方毫米，这表明功能性皮质柱在发育过程中横截面积增加。这些横截面积在出生时比根据前额叶第5层锥体神经元的胞体宽度计算出的面积大55 - 100倍，在48个月时大229 - 277倍。对锥体基底树突的径向范围与其胞体间距离进行比较发现，第3层锥体基底树突在15个月和60个月时分别与1.5个和4.0个其他锥体神经元接触，而第5层超大锥体基底树突在出生时和48个月时分别与1.14个和1.72个其他此类神经元接触。如果这种关系适用于其他皮质区域，那么科内尔的数据可用于估计基底树突范围，目前关于这方面的数据很少。
