It is well known that cell death forms an important part of normal developmental and plastic processes in the brain. For example, during development, proliferating neuronal precursors generate a population of differentiated neurons, some of which make contact with their targets and survive. Neurons that cannot make appropriate targets activate an endogenous gene-directed death program (Cunningham, 1982; Oppenheimer, 1991). Thus, there is an important relationship between cell proliferation, differentiation, and death in neurons.