Brain Development and Neural Plasticity

Brain development, at the species level, has been shaped over many thousands of generations by selective pressures that drive evolution. The construction and development of the human brain occurs over a protracted period of time, beginning shortly after conception and depending on how we view the end of development, continuing through at least the end of adolescence. This chapter provides some background to embryology and describes different stages of neural development. Once a neuron has completed its migratory journey, it generally proceeds along one of two roads: the cell can differentiate and develop axons and dendrites, or it can be retracted through the normative process of apoptosis, a phenomenon that is widespread. The most prolonged changes occur in the wiring of the brain (synaptogenesis) and in making the brain work more efficiently (myelination), both of which show dramatic, nonlinear changes from the preschool period through the end of adolescence.