DNa02

systemDescending and motor neuronsspeciesD. melanogaster3D view2 of 626 cellssources2

DNa02 is a descending neuron of the fruit fly that helps steer walking. Each side has one; its activity rises just before the fly turns toward that side, and it shortens the strides of the legs on the inside of the turn.

Also known as	DNa02 descending neuron
Region	Anterior dorsal brain; axon descends on the same side into the ventral nerve cord
System	Descending and motor neurons
In the display bundle	2 of the 626 reconstructed neurons in the site’s MaleCNS display bundle, which shows 626 of the model’s 166,700 neurons: DNa02 2

What it is

Its name marks a descending neuron (DN) whose cell body lies in the anterior dorsal cluster (a) (Namiki et al., 2018). DNa02 is represented by a single right–left pair, and its activity correlates with the fly’s rotational velocity: the cell in the right hemisphere is more active during right turns, and vice versa (Yang et al., 2024).

Where it sits

Unlike DNg13, another steering-related descending neuron, DNa02’s axon does not cross the midline as it descends into the ventral nerve cord. DNa02 is directly targeted by central complex output neurons responsible for feedback control of heading, and its direct inputs in the brain largely differ from those of DNg13 (Yang et al., 2024).

What it does

DNa02 spiking increases just before a decrease in the stride length of the legs on the same side and a turn toward that side. Stimulating DNa02 on one side shortened the strides of all three legs on that side, mainly by shortening the return stroke; activating both cells slowed the fly without changing its heading (Yang et al., 2024).

Behavior

DNa02 and DNg13 evoke different leg “gestures”: one lengthens strides on the outside of a turn and the other, DNa02, attenuates strides on the inside (Yang et al., 2024).

In TheFlyBrain experiments

DNa02 is the steering readout in many experiments. In the Flight Simulator and Project Pigeon experiments, each measured window turns the scene by a gain times the filtered right-minus-left DNa02 rate, which changes the next retinal image.

8 experiments name these cells in their setup or measurement notes. On the workstation, what the fly sees reaches the fixed 166,700-neuron model and spikes are recorded from cells like these.

• 0001Media ObservationTimed cues stimulate LC10a and LC4/LPLC2 through the engineered movie-cues-v1 encoder. Over 700 ms of model time, mean DNa02 rate plus 0.25 x DNp01 rate is compared with a threshold to request a board visit.
• 0011Motor Circuits BenchNine channels: DNa02 steering, DNp01 escape, DNg100 forward walking, MDN backward walking, BRK halting, DNp09 running/freezing, aDN1 + aDN2 anterior grooming, DNp29 abdominal grooming, MN9 proboscis output.
• 0053The Ludovico TechniqueThe panel reports measured spikes for LC4 + LPLC2 (looming), LC10a (small target), HS + H2 (horizontal motion), DNa02 (steering) and DNp01 (giant fiber).
• 0064Project Pigeon Nose-Cone GuidanceRetinal-only input; DNa02, LC10a and HS + H2 rates are reported as fixed measured readout groups.
• 0067Flight SimulatorCanonical retinal input in 200 ms live windows; measured readouts are DNa02, HS + H2 and EPG.
• 0068T-Maze Odor ConditioningChoice rule: mean measured MBON01–05 (or DNa02) readout per odor over settled sampling windows; the subject avoids the arm whose odor evoked the higher mean.
• 0069Courtship ChamberThe retina sees the moving female; measured LC10a, male pC1 cluster (contains P1), pIP10 and DNa02 rates are shown separately from the timeline-derived courtship index.
• 0071Ganzfeld ProtocolDuring live playback the pick is the total measured spikes in four readout groups (LC10a, LC4 + LPLC2, HS + H2, DNa02) during judging, modulo 4; otherwise it is the seeded, pre-programmed pick.

Sources

1. Yang HH, Brezovec BE, Serratosa Capdevila L, et al. (2024). Fine-grained descending control of steering in walking Drosophila. Cell 187:6290–6308.e27. doi:10.1016/j.cell.2024.08.033
2. Namiki S, Dickinson MH, Wong AM, Korff W, Card GM (2018). The functional organization of descending sensory-motor pathways in Drosophila. eLife 7:e34272. doi:10.7554/eLife.34272

Anatomy in the 3D view: MaleCNS v1.0, FlyEM / HHMI Janelia, CC BY 4.0. Summaries on this page describe published findings in living flies; the workstation’s model is a fixed-weight spiking model of the wiring diagram.

Related

• Descending neurons · About 1,300 neurons that carry commands from the brain through the neck to the ventral nerve cord.
• DNp01 (giant fiber) · The giant fiber: a large descending neuron whose spike triggers a fast escape takeoff.
• PFN neurons · Central complex neurons that combine heading with self-motion signals, a step in computing the direction of travel.
• Leg motor neurons · About 50 motor neurons per leg, recruited in order from slow, weak movements to fast, strong ones.

Glossary: Descending neuron · Ventral nerve cord (VNC) · Central complex