Levels of Plasticity

Plasticity is the ability of the brain to adapt to and change throughout its lifespan. It was previously believed that plasticity was only present in the young brain, but we now know that the adult and old brains are also plastic. This chapter explores the concept of plasticity in the brain and its implications for understanding the neuron and its role in neural and psychological functions. The concept of neural plasticity, as proposed by William James, is discussed in relation to other concepts of plasticity, including phenotypic plasticity, cognitive plasticity, and neural plasticity. The chapter also discusses how the concept of plasticity at the single-neuron level, originally understood as synaptic plasticity, has been broadened to include nonsynaptic forms of plasticity. In addition, findings on neuronal cell generation and the “self-renewing brain” are evaluated. Finally, the role of epigenetic mechanisms in neural plasticity is examined, and the question of how the epigenome in neuronal cells contributes to neuronal survival and adaptability in response to the ever-changing demands of the neuron’s functional context is raised.