Wow! What an interesting read @abigail-dantes. I really liked how you discussed such controversial topic, kept the mystery alive and never actually came to a conclusion on what we don't know. I was really intrigued by the memory formation due to low oxygen conditions point. I don't see why this could not happen. Majority of memory loss is because of cells dying - the ischemic death. However, not all neurons may die at once. At least in transient anoxic conditions, there are some neurons in hippocampus which may stay alive. And, they even show some LTP (a process also involved in memory formation) under such conditions (Hsu and Huamg, 1997). Moreover, we see brain waves decay a few seconds to minutes after cardiac death. However, these are mass recordings of many neurons. It's likely that there some below sensitivity activity might persist in isolated clusters. I don't know, but it would be interesting to look at studies using an invasive array of electrodes to record time after death (at least in animals). I don't know if such studies exist it would be cool if they did. But I think this is the line of inquiry that should follow.

However, there was this interesting study published this year. In this study, the researcher tried to restore the brain of slaughtered animals hours after their death. And they seem to get a good amount of it back online. I think there is more going on in the brain after death than we know as of now. What we are witnessing in NDE might be arising from that underappreciated brain activity post-death. (Or I don't know should we be really calling it death)