Posted 8:53 PM
You can skip most of the bad philosophy espoused in Scientific American's "the hidden mind", a special issue dedicated to attempting to locate our soul using an electron microscope. Ambitious? Yes. Silly. Yes. There is one good article on adult neurogenesis in the issue. Yes, we can make new neurons - but sadly we're not very good at it. Nice newer articles here
and at nature.com
(sciam.com has good "see also" links).
Neurogenesis happens when memories have become integrated, or understood. New neuron's don't "clear out" old memories, but they are simply needed for new ones, after the old memories have been integrated.
When old memories are recalled - it's not a "movie playing back". Our mind "rediscovers" what happened to us based on who we are. Recalling memories is a search algorithm, sort of rapidly "guessing what happened", and then checking if that would have created our current psyche, and then "guessing again". Which is why we often can clearly "remember" wholly false information.