ER [FBbt_00007507]

Ring neuron that develops from the DALv2 neuroblast during the larval stage (Lovick et al., 2017; Omoto et al., 2018; Bridi et al., 2019. Its small soma is located in a cluster just dorsolateral to the antennal lobe and ventrolateral to the lateral accessory lobe (LAL) (Hanesch et al., 1989. There are approximately 150 R-neurons per hemisphere, making them more abundant than the extrinsic ring neurons (Omoto et al., 2018. They have projections that extend dorsoposteriorly, branching off localized neurites with postsynaptic terminals into the bulb or, less frequently, the LAL (Young and Armstrong, 2010; Omoto et al., 2018. They enter the lateral ellipsoid fascicle, and via a circular process, terminate medially into the ellipsoid body (EB) (Omoto et al., 2018. In the EB, distal neurites of R-neurons either project centrifugally (inside-out) or centripetally (outside-in) (Omoto et al., 2018 and have presynaptic terminals there (Young and Armstrong, 2010. They are GABAergic (Bridi et al., 2019. All subtypes have functions in regulating sleep (Yan et al., 2023. (Omoto et al., 2018, Renn et al., 1999, Young and Armstrong, 2010, Hanesch et al., 1989, Yan et al., 2023, Bridi et al., 2019, Lovick et al., 2017)