develops from receives synaptic input in region sends synaptic output to region receives synaptic input from neuron sends synaptic output to cell lamina monopolar neuron L3 medulla layer M1 medulla layer M2 medulla layer M3 medulla layer M8 transmedullary neuron Tm20 Connectivity in the medulla based on EM (Takemura et al., 2013; Kind et al., 2021). Connectivity in the lobula was assessed by GRASP and double-labeling EM (Lin et al., 2016). Neurotransmitter was assessed using a cha-GAL4DBD driver (Gao et al., 2008). VFB:FBbt_00003808 Tm20 Transmedullary neuron that has dendritic arborization in medulla layers M1-M3, as well as presynaptic sites in M8 (Fischbach and Dittrich, 1989; Gao et al., 2008). In the medulla, it spans just one column (Kind et al., 2021), and receives input from lamina monopolar neuron L3 (Takemura et al., 2013) and an R8 photoreceptor (Kind et al., 2021). Its axon follows the anterior edge of its cognate medulla column (Ting et al., 2014), then crosses the second optic chiasma and projects to lobula layer 5 (Fischbach and Dittrich, 1989; Gao et al., 2008). It provides input to the lobula intrinsic neuron Li4 via many synapses (Lin et al., 2016). It is a cholinergic neuron (Gao et al., 2008). There is usually one of these cells per optic column (Nern et al., 2025). FlyBrain_NDB:10145 FBbt:00003808 fly_anatomy.ontology Tm20 photoreceptor cell R8 narrow field transmedullary neuron lobula layer 5 Notch ON hemilineage secondary neuron immature transmedullary neuron Tm20 adult cholinergic neuron lobula intrinsic neuron Li4