It's scientifically observed that the brain still has electrical activity minutes following death and inactivity of other organs. It's the same kinda activity found during dreaming, memory recall/flashbacks and meditation. Your final waves of consciousness could be taking you anywhere. It's assumed your life flashes in replays before your eyes.
From the accounts I've heard of people who have experienced near death experiences, there's always description of there being a bright light, I fully believe that. I think anything else is a personal manifestation based on your life.
They found this when using an EEG to detect the seizures in an epilepsy patient who happened to have a heart attack and pass.
