Circadian Structural Plasticity Drives Remodeling of E Cell Output

DUHART, J.; HERRERO, A.; DE LA CRUZ, G.; ISPIZUA, J.I.; PÍREZ, N.; CERIANI, M.F.

CURRENT BIOLOGY

CELL PRESS

Lugar: United States; Año: 2020 vol. 30 p. 1 - 9

0960-9822

Behavioral outputs arise as a result of highly regulated yet flexible communication among neurons. The Drosophila circadian network includes 150 neurons that dictate the temporal organization of locomotor activity; under light-dark (LD) conditions, flies display a robust bimodal pattern. The pigment-dispersing factor (PDF)-positive small ventral lateral neurons (sLNv) have been linked to the generation of the morning activity peak (the M cells), whereas the Cryptochrome (CRY)-positive dorsal lateral neurons (LNds) and the PDF negative sLNv are necessary for the evening activity peak (the E cells). While each group directly controls locomotor output pathways, an interplay between them along with a third dorsal cluster (the DN1ps) is necessary for the correct timing of each peak and for adjusting behavior to changes in the environment. M cells set the phase of roughly half of the circadian neurons (including the E cells) through PDF. Here,we show the existence of synaptic input provided by the evening oscillator onto the M cells. Both structural and functional approaches revealed that E-to-M cell connectivity changes across the day, with higher excitatory input taking place before the day-to-night transition. We identified two different neurotransmitters, acetylcholine and glutamate, released by E cells that are relevant for robust circadian output. Indeed, we show that acetylcholine is responsible for the excitatory input from E cells to M cells, which show preferential responsiveness to acetylcholine during the evening. Our findings provide evidence of an excitatory feedback between circadian clusters and unveil an important plastic remodeling of the E cells synaptic connections .