Making room for new memories

Joe Tsien (Princeton University, Princeton, NJ) and colleagues have suggested that the creation of new neurons in the hippocampus may allow old memories to be wiped clean, thus making way for the new.

New neurons were thought to form new memories, because widespread adult neurogenesis correlates with song learning in songbirds. But adult primate neurogenesis involves far fewer cells. The new neurons last only a few weeks, during which a memory is transferred from short-term storage in the hippocampus to long-term storage in the cortex.

Tsien found he had a tool for testing the possible link between memory and neurogenesis when he made mice that lacked Presenilin-1 (PS1) in their forebrains. PS1 helps cleave amyloid precursor protein (APP) and Notch, and alterations in PS1 activity are associated with Alzheimer's disease (AD). Mutant...