This told us that the new neurons were not born by division of existing neurons, but were born elsewhere in the brain and went through a migratory stage during which they were not recognized as neurons. It took at least a week for the first new neurons to reach their destination and acquire the looks of an adult neuron.
当我们给成年金丝雀加入带有标签的DNA积木，并且寻找本该早一两天产生的带标签的细胞时，我们没有发现这样的细胞。但是如果我们再等一段时间，比如说，一到三个星期（这根据具体是大脑的哪一部分来定），我们就能许多带有标签的细胞。这表明新的神经细胞不是通过已有的细胞的分裂产生的，而是在大脑的其他地方产生，然后迁徙过来的，而在迁徙过程中，它们并没有表现出是神经细胞。最初的新神经细胞至少需要一周时间才会到达其目的地，并表现出是成年的神经细胞。