The developing nervous system was the subject of this week’s reading. The structure of the neurons begins with a collection of stem cells which go through 3 stages to form the basis of the nervous system. These are:
The cortex is said to develop “inside out” because the first cortical plate cells become the last layer of of neurons (in this case, layer VI followed by V, IV etc.). As a side note, I wonder why both neuroscience and music theory insist on using Roman numerals for some things? I understand it has to do with history, but it’s a pretty confusing written number system.
One of the more on-topic things this chapter made me wonder about was the hippocampus. Neuroscientists have been able to timestamp the cells of people who lived through nuclear weapons testing during the cold war based on the radiation present. When examining the postmortem brains of these subjects, it was determined that people do not develop new neurons throughout life except in the hippocampus. Further testing showed that hippocampal cells renew continuously, and we essentially end up with a new one every year.
This made me think about the famous case of HM, who had severe anterogade amnesia after his hippocampus was cut in an effort to stave off seizures. HM’s hippocampus was clearly not able to re-wire itself to full function, so I am wondering how his hippocampal cell regeneration might have affected his brain function.
Thinking about this cellular regeneration also made me wonder about possible blips in the process. For instance, are there theories of de ja vous that involve hippocampal function, since it is so integral to memory?