Plasticity in the Adult Brain

Although commonly associated with development, structural growth is a feature of the brain that endures well into adulthood. Numerous studies have shown that dendritic complexity and synapse number change as a result of experience in a number of brain regions to varying degrees, and some studies have causally linked these forms of structural plasticity to neuronal function and behavior. One brain region exhibiting widespread structural plasticity in adulthood is the hippocampus, which undergoes a number of dynamic alterations in response to stress, exercise, environmental enrichment and learning. The plastic nature of the adult hippocampus likely influences cognition and behavior, maximizing the ability of the organism to respond to complex environments. One of the most intriguing aspects of hippocampal plasticity is the ability to generate new neurons in the dentate gyrus throughout life. Adult-born granule cells possess unique function and connectivity, promoting experience-dependent plasticity in a highly dynamic manner. This chapter reviews what is known about this fundamental form of plasticity, while making connections with other types of structural plasticity within the hippocampus and throughout the brain.