The New York Times reports on a journal article in Nature on how memory works in a neurobiological sense – the brain suppresses or forgets memories in order to enable a person to remember more interesting or important things. So as the article says:
Blocking out a distracting memory is something like ignoring an old (and perhaps distracting) acquaintance, experts say: it makes it that much harder to reconnect the next time around. But recent studies suggest that the brain plays favourites with memories in exactly this way, snubbing some to better capture others. A lightning memory, in short, is not so much a matter of capacity as it is of ruthless pruning — and the new study catches the trace of this process at it happens.
So once again it seems all my problems stem from my inability to make fast decisions. I’m forgetting inappropriate things not because I’m going senile but rather because my poor overloaded brain can’t decide which memories to suppress.  I just think everything is equally important, so I forget to feed the pets but remember that Peter Murphy’s album “Dust” was presaged by the song Huuvola on his album “Cascade”.
That brain thing sure is tricky