Daily rewiring of adult networks in Drosophila.

CERIANI MF

Montevideo

Congreso; XII Congress International Society for Neuroethology. Symposium ¨A brain within the brain¨.; 2016

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 subset known as the small ventral lateral neurons (sLNvs) are essential; in fact, 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) as well as classical neurotransmitters whose role has only recently been explored. In addition to the release of signaling molecules, sLNv axonal terminals undergo extensive remodeling on daily basis, and such plasticity in the number of synapses could provide an alternative means of encoding time-of-day information. A number of years ago we 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 possibility that circadian structural remodeling provides a mechanism by which a neuron can exert sequential control of different target circuits along the day.