IN THIS discussion I have chosen to sample the burgeoning field of neurobiology in an attempt to relate this field to clinical problems of the developing nervous system. Before doing that, I shall consider some of the present concepts about the nervous system, and question whether they will hold up over the coming years.
One of the questions concerns the concept that the development of the nervous system is a carefully programmed event, with little room for variation and little flexibility. I should like to question this concept in terms of the criteria listed below:
Stages of Neuronal Development
Neuronal formation First trimester
Neuronal migration Second trimester
Neuronal interconnection Third trimester and Postnatal
Myelin formation Postnatal
There is considerable evidence that the concept of a specific time for neuronal formation is too rigid. On the contrary, there are neurons which continue to form during fetal development, and, in