title: A pair of identified giant visual projection neurons demonstrates rhythmic activities before eclosion.
abstract: A small set of neurons acting as an internal clock in the Drosophila brain is critical for regulating circadian activities behavior and pre-adult development. However, the cell basis for the circadian rhythm in correlation with light sensitivity is not fully understood. Here we identified a pair of giant visual projection neurons located laterally to the calyx of the mushroom bodies, and investigated their electrophysiological, morphological characteristics, as well as the development pathways during eclosion. The typical morphology of these giant neurons showed the size of the soma (16.0±0.6 microns in diameter) and its processes. Interestingly during development, the three major branches shrunk significantly along with gradually decreased rhythmic spikes. Furthermore, the electrical activity of the giant visual projection neurons is circadian-regulated, shown with significantly higher resting membrane potential, increase in frequency of spontaneous action potential firing, and burst firing pattern during circadian day and night time. The similarities in the morphological characteristics with other visual projection neurons highly suggest that this neuron is a type of novel visual projection neurons in this area, which has special properties in light sensitivities and rhythmic activities. Our data provided supporting evidence for the visual projection neurons with light sensitivities, and pointed to the potential correlation of visual projection neurons and circadian rhythms during the eclosion period or an adaptive development for higher sensitivity of light in adult visual systems.
authors.affiliation: Department of Anatomy and Neurobiology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou Guangdong Province 510080, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Yan
authors.forename: Ye
authors.initials: Y
authors.lastname: Xu
authors.forename: Shengwen
authors.initials: S
authors.lastname: Deng
authors.forename: Naya
authors.initials: N
authors.lastname: Huang
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.forename: Jiahe
authors.initials: J
authors.lastname: Qiu
authors.forename: Jinchao
authors.initials: J
authors.lastname: Liu
authors.forename: Xutian
authors.initials: X
authors.lastname: Wang
authors.forename: Guangxin
authors.initials: G
authors.lastname: Yang
authors.forename: Huaiyu
authors.initials: H
authors.lastname: Gu
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D048430:Cell Shape / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D004331:Drosophila melanogaster; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*
keywords: Drosophila melanogaster; Eclosion; Firing patterns; Visual projection neurons