Lobula columnar (LC) and LPLC neurons
systemVisionspeciesD. melanogaster3D view107 of 626 cellssources5
Lobula columnar (LC) and lobula plate–lobula columnar (LPLC) neurons are visual projection neurons of the fruit fly: they carry features extracted in the optic lobe to the central brain. The axons of each type converge in their own optic glomerulus.
| Also known as | LC neurons · LPLC neurons · Visual projection neurons · VPNs |
|---|---|
| Region | Lobula and lobula plate; axons end in optic glomeruli of the central brain |
| System | Vision: eye and optic lobe |
| In the display bundle | 107 of the 626 reconstructed neurons in the site’s MaleCNS display bundle, which shows 626 of the model’s 166,700 neurons: LC4 25, LC6 1, LC9 1, LC10a 29, LC10b 1, LC10c 1, LC12 2, LC13 1, LC15 2, LC17 4, LC18 1, LC26 1, LC28a 1, LC29 1, LC33 1, LPLC1 1, LPLC2 32, LPLC4 2 |
What they are
A systematic survey of visual projection neurons found that the terminals of each columnar lobula pathway form a glomerulus-like structure in a different area of the ventrolateral protocerebrum (Otsuna and Ito, 2006). A later study described 22 LC types anatomically (Wu et al., 2016). Most target optic glomeruli in the posterior ventrolateral and posterior lateral protocerebrum (PVLP and PLP), while LC10 terminals lie in the anterior optic tubercle (Wu et al., 2016). A connectome of one optic lobe of a male fly classifies its roughly 53,000 neurons into 732 types, which include the LC and LPLC types (Nern et al., 2025).
LPLC types also have dendrites in the lobula plate, where T4 and T5 cells sort motion by direction (Klapoetke et al., 2017).
What they do
Optogenetic activation of several LC types in freely moving flies evokes specific behaviors. Two types evoke avoidance resembling the response to a looming object and respond to looming stimuli in calcium imaging, whereas another responds instead to the motion of a small object. Activating LC neurons on one side of the brain can cause turning toward or away from that side, depending on the type (Wu et al., 2016).
Instead of keeping a map of visual space in their axons, these neurons convey where a feature is through graded numbers of synapses onto downstream neurons. This synaptic gradient motif was found across all 20 primary visual projection neuron types examined (Dombrovski et al., 2023).
Examples
Well-studied types include LC4 and LPLC2, which detect looming and connect to the giant fiber escape neuron, and LC10a, which male flies need to follow a female during courtship.