ScienceDaily (here) has an item on an interesting paper: Loretxu Bergouignan, Lars Nyberg, and H. Henrik Ehrsson. Out-of-body–induced hippocampal amnesia. Proceedings of the National Academy of Sciences, March 10, 2014.
Our feeling of our bodies is important to storing/retrieving episodic memories. The experimenters had subjects using virtual reality googles which either left them with their own bodies or forced an ‘out-of-body’ illusion. The subjects could remember the events that happened when their body image was not disturbed. When they tried to remember events that happened when they felt out of their bodies – they had difficulty. Henrik Ehrsson is quoted as saying,“The fMRI scans further revealed a crucial difference in activity in the portion of the temporal lobe — the hippocampus — that is known to be central for episodic memories. When they tried to remember what happened during the interrogations experienced out-of-body, activity in the hippocampus was eliminated, unlike when they remembered the other situations. However, we could see activity in the frontal lobe cortex, so they were really making an effort to remember.”
I am inclined to think that memory is a question of saving experiences that may be useful. We know that the hippocampus associates our location with events in memory and that it tracks the timing or ordering of events. There is also often a mood and emotional colouring to remembered events. And extremely important is the sense of how much is invested and how much ownership is taken in events. We remember effort. We remember errors. We remember hard decisions. We remember good places and people and we remember bad ones too. To put it simply, we remember what may be useful. What happened when our bodies were not involved is not very useful – it might as well be someone else’s event.
I remember things that happened to other people and I can picture them happening to me. But I know that it did not happen to me. My body was not there. Those memories started as words in a story being told to me and they carry that lack of first-hand involvement. What happens with an experience that has neither our own body’s involvement nor someone else’s body? Perhaps it is – no identifiable agent – no memory.