The sudden loss of many brain cells as a result of strokes or injuries must have serious effects on an animal’s survival. It seems likely that the replacement of neurons in the adult brain did not evolve to make up losses due to illness or lesion, but as a process of constant renewal, a few cells being replaced every day.
这里并没有什么医院存在。因为中风或受伤而突然损失许多脑细胞会严重影响动物的生存。看起来似乎成年大脑内神经细胞的替代并不会弥补因为疾病或损伤而产生的损失，而只是一个持续的更新过程——每天都有一些细胞被替代。