From Nature:
Old age does more than stealthily steal away our most cherished memories: it also seems to diminish our ability to imagine things. This finding, detailed in the January issue of the journal Psychological Science, supports the ‘prospective brain’ hypothesis, the idea that imagining the future and remembering the past rely on the same neural machinery. “One implication of this study is that imagining is quite closely related to, and dependent on, remembering, perhaps more so than we previously realized,” says Dan Schacter of Harvard University.
Over the past year, the prospective brain hypothesis has gained steady support among neuroscientists. An intriguing possibility raised by the hypothesis is that the primary role of human memory may not be to remember the past, but to imagine and prepare for the future.
More here.