As many people know, I died on one occassion. When I died, I found myself in a place filled with many clouds, but I myself upon a long stone road that weaved through them.
The road was indeed very long, and full of perils, but eventually I made it to the end and trained with a martial arts master on his secret planet until I was strong enough to return and save my friends from some dangerous aliens.
Later, they would wish me back to life using a magic dragon.
This is fantastic. Thank you, Captain.
As for the planaria study MSH, there's a lot more at work than just the possibility of memories being physically transferable. I find this a more likely explaination:
The worms had not been trained at all, simply their level of sensitivity to all stimuli had been increased. If anything was transferred it was a sensitising substance.
They picked up sensitizing hormones from the dead worms, who had built them up in response to experiencing the shock experiment. Planarians are much, much simpler organisms, to the point that they barely have specialized tissues. Their bodies are generic enough that they could be affected similarly by hormones from other Planeria, picked up from their diet or environment.
On topic: if death is anything like losing consciousness due to hypoxia, I can tell you that it feels deeply wrong and distressing, and despite the pain and distress it may cause, and all your fighting to stay conscious, you still just slip out of awareness in time. From there on out it's nothingness, unless you manage to regain awareness and consciousness later on... and then you just have a gap... knowledge that you were gone, but no awareness of time passed, or what happened.