Title: Structural Neural Plasticity In the Circadian Clock Neuron Network of Drosophila

Speaker: Dr. Orie Shafer, City University of New York


Circadian clocks drive daily rhythms in gene expression, physiology and behavior and their proper entrainment to environmental cycles is critical for health. Neural networks within the circadian clock centers of the brain display marked daily changes in neuronal morphology.  In Drosophila melanogaster, the daily structural remodeling of the dorsal medial termini of the critical small ventral lateral neurons has long been hypothesized to mediate circadian timekeeping and the proper timing of circadian behavioral outputs.  To challenge this model, we have specifically abrogated the normal sites of daily neuronal remodeling in these neurons through the reprogramming of neural development to assess the effects on circadian timekeeping and the timing of clock outputs. Unexpectedly, we find that the loss of sites of daily remodeling has no measurable effects on endogenous circadian timekeeping or any of the major output functions of the small ventral lateral neurons.  Rather, we find that the dynamic termini of these cells mediate sensory input into the circadian network and support the proper integration of naturalistic time-cues from the environment.  Furthermore, we show that this integration is mediated by glutamate gated chloride channels expressed in the small ventral lateral neurons.  These results fail to support long standing conclusions regarding the role of structural plasticity in the Drosophila clock neuron network and provide clear evidence that the sites of structural remodeling in critical clock neurons mediate sensory input, integration, and entrainment.

Host: Dr. Donggen Luo