develops from expresses receives synaptic input in region sends synaptic output to region sends synaptic output to cell sim T5 neuron medulla layer M1 medulla layer M2 medulla layer M3 medulla layer M4 medulla layer M5 transmedullary neuron Tm9 VFB:FBbt_00003797 Tm9 fly_anatomy.ontology FBbt:00003797 Transmedullary narrow field neuron that has most of its dendritic arborization in medulla layers M2 and M3, with some extensions into M1, M4 and M5 (Gao et al., 2008; Ting et al., 2014), and presynapses in M3 (Gao et al., 2008). Its axon follows the posterior edge of its cognate medulla column (Ting et al., 2014), then crosses in the second optic chiasma and terminates in lobula layer 1 (Fischbach and Dittrich, 1989; Ting et al., 2014), where it outputs to T5 neurons (Shinomiya et al., 2014). It is a cholinergic neuron (Gao et al., 2008; Shinomiya et al., 2014). It expresses the transcription factor sim (Ozel et al., 2021). There is usually one of these cells per optic column (Nern et al., 2025). Tm9 https://cdn.ncbi.nlm.nih.gov/pmc/blobs/bae0/7069908/ef7abe34662d/359_2019_1375_Fig2_HTML.jpg Neurotransmitter was assessed using a cha-GAL4DBD driver (Gao et al., 2008), single-cell transcript profiling and immunohistochemistry (Shinomiya et al., 2014). Connectivity in the lobula was assessed by serial section electron microscopy of a single column (Shinomiya et al., 2014). FlyBrain_NDB:10163 lobula layer 1 narrow field transmedullary neuron Notch ON hemilineage secondary neuron immature transmedullary neuron Tm9 adult cholinergic neuron