Monica Rocha

The emergence of functional maturity in the brain relies upon the interplay between form and function during its developmental history. This interaction continues throughout life and changes in neuronal function lead to changes in diverse structural scales in the brain. Both regulatory genes, which define compartments in the nervous system, and activity-dependent processes cooperate to determine neuronal phenotype and tissue structure. The influence of electrical activity as a regulator of early developmental events such as proliferation and migration is being considered. Spontaneous neuronal activity may influence early axonal and dendritic arbor formation and activity blockade alters branch density both for axon arbors and dendrites. Although large-scale changes in axon morphology may occur until late stages of development, the remodeling of axon and dendrite morphology in terms of their terminal arborization area is less pronounced than initially thought. Electrical (or ‘neural’) activity is important for synapse stabilization and circuit formation and sensory experience performs a refinement of neuronal shape. This fine-tuning appears to be a dynamical process sustained into adulthood, with smaller scale changes occurring mainly at the dendritic spine level. These subcellular compartments are now believed to restrict biochemical changes in dendrites to particular synapses during (or ‘undergoing’) synaptic plasticity. Events at dendritic spines underlie alterations in the morphology of individual neurons that will ultimately affect the function of complex neuronal networks.