Mi4 [FBbt_00003779]

Mi4

ID: FBbt_00003779

Medulla intrinsic narrow field neuron with both fine and bleb-type arborizations in medulla layers M1, M2, M3 and M8, but with only fine arborizations in medulla layers M4 and M5, and only bleb-type arborizations in medulla layer M9 (Morante and Desplan, 2008; Fischbach and Dittrich, 1989). It receives input from the lamina monopolar neuron L5 and photoreceptor R8 (Takemura et al., 2013). It is a GABAergic neuron (Takemura et al., 2017). There is usually one of these cells per optic column (Nern et al., 2025).

Raghu and Borst (2011) identified this as glutamatergic using a vGlut[CNSIII]-GAL4 driver (FBti0129148), but vGlut antibody staining performed by Takemura et al. (2017) was not strong compared to neighboring cells, whereas GAD1 staining was strong. Pre- versus postsynaptic innervation judged by scoring of terminal morphology from figures in Fischbach and Dittrich (1989) as assessed by FlyBrain Neuron DB. Connectivity in the medulla was assessed by electron microscopy reconstruction from 7 columns (Takemura et al., 2013). Kind et al. (2020) say that it is not contacted by R7/R8 in the DRA, but not clear whether Mi4 is present in the DRA.