Neuronal loss and cell replacement
Choose a lesion or repair condition to compare movement and neuronal firing.
Companion to Habib P, Petr M, Rust R. Focal neuronal loss and cell replacement in a connectome model of fly steering. bioRxiv 2026. doi:10.64898/2026.10.26.762043
Matched flight example
One saved realization · same gust sequence · 10 seconds
Motor-neuron firing
Looming input · 300-ms neural trialLoading matched firing recordings…
View flight paths from above
The same origins and meter scale are used in both views. Forward and lateral displacement refer to the starting heading. Dots mark one-second intervals.
Horizontal paths are model data. Fly shape, wing motion, altitude and trees are illustrations. These are steering simulations without full flight biomechanics.
Function across lesion sizes
Lines connect tested conditions. They do not describe change over time or impose a smooth recovery curve.
How to read the model
Neurons, connections and movement
The model uses 165,122 neurons from the male fly CNS connectome. Visual inputs generate spikes; motor responses determine turning and forward movement in a simplified steering controller.
Site 20 affects a descending motor-control interface. It is not a fly equivalent of motor cortex. Its 1,000-cell lesion removes 37 descending and four lobula plate tangential neurons.
What the uncertainty means
Each result uses 100 neural and intervention realizations within one reconstructed nervous system. Movement is averaged over 20 matched gust sequences before calculating uncertainty. These are model realizations, not 100 animals.
Lesion bands show the central 95% simulation range, matching Figure 1f. Replacement bands show pointwise 95% confidence intervals for the mean, matching Figure 2c. The animation shows one prespecified example, not the mean path.
What replacement means here
Original repair is an ideal reconstruction of selected lost cells and their available partners. Full original repair reproduces intact by construction. A graft with the correct types instead inherits connections from surviving cells of those types.
At full dose, 42 untyped positions in the correct-type condition receive sampled lost-cell identities. Replacement is immediate in the model; graft maturation and spontaneous recovery are not simulated.
Interpreting the readouts
Intact function is one. Values above one can occur and are retained. Wing-motor and looming readouts measure neural activity, not physical wing posture or observed takeoff. Virtual crossings describe flight planes, not walking beam counts.
The controller retains a minimum forward speed, so severe lesions can leave small residual displacement even at zero neural motor drive.
Source data
The controls use the final results of the preprint and tested 0–2,000-cell replacement series. Firing traces recover the same first neural realization and are verified against its saved rates.
Only tested combinations are offered. The 56-site exploratory screen and additional controls remain in the manuscript.