Aging-related neurodegeneration eliminates male courtship choice in Drosophila.

Choices between 2 options, one liked and one disliked, are effortless for an animal, whereas those among 2 equally liked options are more difficult to determine and might depend on an unknown mechanism. Here, we report that in the fruit fly Drosophila melanogaster, both younger virgin females and older ones are "liked options" to males. However, when given the choice, males tend to be fastidious and prefer younger virgin females to older ones. Besides, aging eliminates males' preference for younger mates, which can be mimicked by ectopically expressing the human amyloid precursor protein in their central nervous system. Furthermore, we examined the effect of neurodegeneration in Drosophila courtship circuit and confirmed that male courtship preference for younger mates was abrogated by neurodegeneration. Our work, thus characterizes a novel choice behavior that can be decisions after comparison and also reveals the critical role of neurodegeneration in this behavior, which provides new insights on decision-making mechanisms.