Clock connectomics (Simposio ¨ Neural circuits III¨)

CERIANI MF

Big Sky, Montana

Congreso; Congreso bianual de la Society for Research on Biological Rhythms; 2014

Society for Research on Biological Rhythms

Circadian rhythms regulate physiology and behavior through the action of self-sustained transcriptional feedback loops of clock genes operating in discrete groups of neurons. In Drosophila, about 150 neurons in the central brain are implicated in the circadian regulation of rest-activity cycles, but a small subset known as the small ventral lateral neurons (sLNvs) are essential. Preservation of molecular oscillations within this cluster is key to command rhythmic behavior in the absence of environmental cues. The sLNvs transmit time-of-day information releasing a neuropeptide known as pigment dispersing factor (PDF), and other yet unidentified classical neurotransmitters. The sLNv axonal terminals in adult brains also undergo extensive remodeling on daily basis, and such structural plasticity could provide an alternative means of encoding time-of-day information. We have recently carried out an unbiased screen to map the connectivity of sLNv neurons using GRASP (GFP reconstitution across synaptic partners). Remarkably, GRASP analysis revealed that sLNv terminals contact different target cells along the day, thus extending the impact of core pacemaker neurons to circuits beyond the circadian network. This finding opens the attractive possibility that circadian structural remodeling provides a mechanism by which a neuron can exert sequential control of different target circuits along the day. In sum, our long term interest is to understand how the molecular clock communicates with other clocks in the brain and the body to ensure a coherent response to daily changes in the environment.