Adult Neurogenesis Reconciles Flexibility and Stability of Olfactory Perceptual Memory

Abstract

The abilities to learn and store memories are inherently at odds with each other: the brain must be flexible enough to quickly store new information, but stable enough to avoid overwriting old memories. We show that adult neurogenesis can overcome this flexibility-stability dilemma. We develop a computational model for adult neurogenesis and structural spine dynamics in the olfactory bulb that captures many experimental observations and show that the transient properties of adult-born neurons confer multiple contributions to addressing this problem. First, the enhanced plasticity of young neurons allows them to flexibly encode new memories; as the neurons age, these memories stabilize, while remaining in the same neural ensemble. Second, the young new neurons' enhanced excitability and susceptibility to apoptosis maintain the flexibility of the memory. Finally, the period of sensory-dependent dendritic elaboration establishes an additional substrate of memory that facilitates rapid relearning. The model makes experimentally testable predictions and identifies a new functional role of adult neurogenesis in olfaction: memory consolidation.