experience-induced changes in dendritic spine stability also point to spine turnover as a mechanism involved in the maintenance of long-term memories, though it is unclear how sensory experience affects neural circuitry. two general models might describe the impact of experience on structural plasticity. on the one hand, experience and activity may drive the discrete formation of relevant synaptic connections that store meaningful information in order to allow for learning. on the other hand, synaptic connections may be formed in excess, and experience and activity may lead to the pruning of extraneous synaptic connections.