Circadian Neuropeptide-Expressing Clock Neurons as Regulators of Long-Term Memory: Molecular and Cellular Perspectives.

The neuropeptide pigment-dispersing factor (Pdf) is critically involved in the regulation of circadian rhythms in various insects. The function of Pdf in circadian rhythms has been best studied in the fruitfly, i.e., . Pdf is produced in a small subset of circadian clock neurons in the adult brain and functions as a circadian output signal. Recently, however, Pdf has been shown to play important roles not only in regulating circadian rhythms but also in innate and learned behaviors in . In this mini-review, we will focus on the current findings that Pdf signaling and Pdf-producing neurons are essential for consolidating and maintaining long-term memory induced by the courtship conditioning in and discuss the mechanisms of courtship memory processing through Pdf-producing neurons.