Survival of adult basal forebrain cholinergic neurons after loss of target neurons.

Target cells are thought to regulate the survival of afferent neurons during development by supplying limiting amounts of neurotrophic factors, but the degree to which afferent neurons remain dependent on target-derived support in the adult is uncertain. In this study, uninjured basal forebrain cholinergic neurons did not die after excitotoxic ablation of their target neurons in young adult rats, indicating that they are either not dependent on neurotrophic factors for survival or can obtain trophic support from other sources after target neurons are lost. This finding suggests that cholinergic cell death in neurodegenerative conditions such as Alzheimer's disease is not due solely to a loss of target neurons or factors provided by them.