Adult neurogenesis in the olfactory system and neurodegenerative disease.

The olfactory system is unique in many respects-two of which include the process of adult neurogenesis which continually supplies it with newborn neurons, and the fact that neurodegenerative diseases are often accompanied by a loss of smell. A link between these two phenomena has been hypothesized, but recent evidence for the lack of robust adult neurogenesis in the human olfactory system calls into question this hypothesis. Nevertheless, model organisms continue to play a critical role in the exploration of neurodegenerative disease. In part one of this review we discuss the most promising recent technological advancements for studying adult neurogenesis in the murine olfactory system. Part two continues by looking at emerging evidence related to adult neurogenesis in neurodegenerative disease studied in model organisms and the differences between animal and human olfactory system adult neurogenesis. Hopefully, the careful application of advanced research methods to the study of neurodegenerative disease in model organisms, while taking into account the recently reported differences between the human and model organism olfactory system, will lead to a better understanding of the reasons for the susceptibility of olfaction to disease.