Cragg B G
Brain. 1975 Mar;98(1):81-90. doi: 10.1093/brain/98.1.81.
The densities of synapses and neurons were measured in 7 neurosurgical specimens of cerebral cortex, regarded as normal controls. The average result was 6 times 10-11 synapses/cm3, 15-6 times 10-6 neurons/cm3, and 38,000 synapses per neuron. Specimens of frontal and temporal cortex from 7 ageing brains (68 to 89 years) gave closely similar counts of neurons and synapses. Seven specimens from 3 severely retarded brains gave similar counts of neurons and slightly higher counts of synapses. A deficit of synaptic development is thus not a necessarre discussed.
在7个被视为正常对照的大脑皮质神经外科标本中测量了突触和神经元的密度。平均结果为6×10⁻¹¹个突触/立方厘米、15 - 6×10⁻⁶个神经元/立方厘米以及每个神经元有38000个突触。来自7个老年大脑（68至89岁）的额叶和颞叶皮质标本给出了与之非常相似的神经元和突触计数。来自3个严重智力迟钝大脑的7个标本给出了相似的神经元计数以及稍高的突触计数。因此，突触发育不足并非必然。 （注：原文中necessarre拼写错误，可能是necessary，这里按正确理解翻译）
