Answer: Hippocampus
Explanation:
Hippocampus is the part of brain section that is situated in temporal lobe .It functions of memorizing , motivation and learning process through brain in limbic system.
If hippocampus faces any damage then there are chances of memory loss or inability to generate long term memories etc in the person who experienced accident .
According to the question,Christopher might have damaged hippocampus as he is not able to produce new memories due to the accident that resulted in damaging brain section.
