Experiments on nervous systems, run on their measured wiring.
NeuroCause turns published connectomes into models you can experiment on: closed-loop simulations whose assumptions are stated, assays that reproduce exactly from their seed, and a causal trace behind every result. Our first model is the fruit fly Drosophila melanogaster — 7,270 brain neurons from FlyWire and 1,045 nerve-cord neurons from MaleCNS, driving a modelled body.
Film: the simulated fly brain, every neuron at its measured FlyWire position. Each flash is a spike from a real model run; midway, a looming stimulus makes the giant fiber fire. Model activity, not a recording from a fly.
Measured wiring. Stated models. Traced causes.
A connectome records which neuron connects to which, and how strongly. It does not record how the cells behave in time. NeuroCause keeps the two apart: the wiring is used exactly as published, and whatever the connectome does not contain is a documented model component, labelled as such wherever its results are shown.
Measured
Anatomy from electron microscopy
Neurons, their positions, cell types and synaptic connections come from peer-reviewed connectome releases, with their licences and a SHA-256 fingerprint of every file. Nothing is tuned by hand to make a behaviour look right.
Modelled
Dynamics, senses and body as stated models
Spiking neuron dynamics, sensory transduction, a jointed body and its contact with the ground. Each component is documented with its parameters, its sources and its limits.
Traced
Every result has a traceable cause
When the model acts, NeuroCause shows which input changed, which sensory neurons it reached and which synapses drove the deciding neurons — from recorded spikes, not from a story told afterwards.
Perturb, measure, compare, trace
An assay in NeuroCause is a protocol, a model and a statistic. It perturbs the model the way a wet-lab experiment would, measures the outcome over many seeded trials, compares it with the published finding, and traces what caused it.
Virtual genetics
Silence or activate any identified cell type, as with a genetic effector — and measure which cells a behaviour actually needs.
Transmitter-class pharmacology
Scale excitatory, inhibitory or modulatory synapses and read out dose–response curves. A test of circuit dependence, not a drug model.
Sensory stimulation
Looming, wind, sound, temperature, taste and touch reach only the receptor neurons that transduce them, so each stimulus is specific by wiring.
Benchmarks from the literature
Classic findings re-run as controlled experiments, with exact tests, confidence intervals and the published result side by side — including the ones not reproduced.
Causal tracing
For every action: the triggering input, the receptors it reached and the synaptic drive onto the deciding neurons, recorded from the run itself.
Provenance by construction
Every run records its seeds, model version and data fingerprints and exports as CSV. Results reproduce exactly and can be compared across model variants.
One framework, one nervous system at a time
The assays do not depend on the animal. A model enters NeuroCause when its wiring is published and its behaviour can be tested; it is ready when it passes its benchmarks. The fruit fly comes first because it is both completely mapped and central to biomedical research.
Available · release 2.2
Drosophila melanogaster, brain and leg circuit
7,270 brain neurons of an adult female (FlyWire FAFB v783) and 1,045 nerve-cord neurons of an adult male (MaleCNS v1.0), joined by a modelled interface between identified descending cell types, in closed loop with a modelled body in a terrarium. She walks, grooms, tastes, sleeps and escapes; ten guided assays ship with their literature.
In development
One fly, brain and nerve cord from the same animal
The BANC connectome maps the brain and the nerve cord of a single female fly. A model built on it removes today’s join between two specimens. The data are acquired and already browsable as anatomy; the model is done when it passes the current benchmarks end to end.
Planned
Comparison connectomes
The male nerve cord (MANC), the male optic lobe and the hemibrain are acquired as references: a cell type found in several animals lets an assay ask whether a result depends on the individual whose wiring was measured.
Vision
Beyond the fly
As further whole-nervous-system connectomes are published, they can join the same assays, statistics and provenance. Which ones, and when, depends on the data — we announce models when they exist, not before.
Does the fly model behave like a fly for the right reasons?
Classic findings from fly neuroscience, re-run as controlled in-silico assays with the statistics shown. Where the model does not reproduce a finding, the Evidence page says so.
Looming escape
An abrupt loom triggers takeoff through the giant fiber — 50% threshold at loom intensity 0.14, 100% from 0.16, none at 0.12 and below. Silencing LC4 cuts giant-fiber spikes by 94%; silencing LC4 and LPLC2 together abolishes the escape.
Mechanosensory specificity
Wind does not trigger escape — 0/12 takeoffs, as in real flies, which stop rather than flee in wind. Only the auditory Johnston’s-organ neurons are wired to the giant fiber; that sound of equal strength drives it (12/12) is a prediction of the wiring.
Taste decisions
Sugar drives proboscis extension; bitter vetoes it — 88% extension at sugar 0.75 alone, 0% once bitter is added (Fisher p = 0.0014), from the measured gustatory pathways.
Self-care
Dust on the antennae triggers head grooming — 100% at full dust, 0% with the JO-F mechanosensors or the DNg12 command neurons silenced (Fisher p < 0.001).
In-silico pharmacology
Inhibition acts as a dose–response on escape — scaling all inhibitory synapses suppresses takeoff from 100% to 0%, half-maximal at 1.52× normal strength. A transmitter-class experiment, not a drug model.
Honest limits
Not every finding is reproduced — habituation, associative learning, thermal preference and three of ten activation phenotypes are not yet. They are listed with their data, because they define the next model work.
All ten benchmark assays, figures, data and the verification suite →
One animal, from brain to nerve cord
Five short films of the BANC connectome — a complete brain-and-cord wiring diagram of a single female fly, and the dataset of our next fly model. Select one to watch it with its original soundtrack.
Connectome: BANC v888, Bates, Phelps, Kim et al., Nature 656 (2026), doi:10.1038/s41586-026-10735-w; data doi:10.7910/DVN/7WTH1N, CC BY 4.0. Visualisation by NeuroCause: a selection of mapped cells and contact links; light pulses illustrate model activity and are not recorded neural firing. Original soundtrack.
What it is for
Research: hypotheses before the wet lab
Silence or activate any identified cell type, change transmitter-class gains, and measure the behavioural consequence in hundreds of seeded trials — a fast way to ask which cells a circuit needs before designing the genetic experiment.
Teaching: circuits you can take apart
Students see sensation become decision become movement, neuron by neuron, and can test each step themselves. The guided assays ship with their literature and statistics.
Methods: a testbed for connectome models
Every run records its seeds, model version and the SHA-256 fingerprint of each data file. Results reproduce exactly, so model variants — and, in time, different animals — can be compared on the same assays.
Towards replacing animal experiments Vision
Our long-term aim is in-silico assays accurate enough to answer some questions that today require animals — including early-stage screening of neuroactive compounds. What that requires, and how far we are, is set out openly. Vision & roadmap
A laboratory, not an animation
Nervous systems that exist only as data — and the question of what it would take for one to feel.
Complete connectomes of the adult fly brain and of its whole central nervous system have been published within the last two years. For the first time, an entire animal nervous system can be simulated on its measured wiring. NeuroCause follows that path step by step: one specimen, cell-type physiology, a calibrated body, validated behaviour — and then the next nervous system.
Whether a simulated nervous system could ever have experiences is an open scientific question. We treat it as one: with published criteria, testable components and no claims beyond the evidence.
NeuroCause for Windows · release 2.2
The application with the fly model, free and without advertising, for Windows 10 and 11 (64-bit). Because the FlyWire brain data carries a non-commercial licence, it is and remains free of charge. By downloading you accept the software terms.
Windows, portable
Release 2.2.0 as a ZIP of about 170 MB. Unzip it anywhere and start the application; nothing is installed and nothing connects to the internet. This release still carries the project’s earlier name in its file and program names.
Source code
Code, data pipeline, tests and the build script, public on GitHub under a non-commercial licence.
Research and teaching
Questions, a collaboration, or the fly model in a course? Write to us.
NeuroCause is a research and teaching tool. It is not validated for medical, veterinary, regulatory or safety decisions, and its pharmacology settings do not predict the effect of any real substance.
Help the next nervous system come to life in silico.
NeuroCause is an independent in-silico laboratory: it runs models of nervous systems on connectomes published by research institutions and tests them with assays anyone can repeat. It is free, open to everyone and carries no advertising — and stays that way because people choose to support it.
- Computing power for simulation runs, validation and films rendered from the models
- New assays and models, each checked against the published literature
- Free for everyone: classrooms, students and researchers, without ads or accounts
Thank you.
You just helped a simulated brain grow. Your support keeps NeuroCause free for everyone who wants to see a nervous system at work.
NeuroCause is an independent, non-commercial project, not a registered charity. Donations are voluntary gifts to the project as a whole and are not tax-deductible. Terms · Privacy
Built on published connectomes
NeuroCause uses public research data under its original licences, with attribution. SHA-256 fingerprints of every data file are recorded in each run and listed on the Evidence page.
| Dataset | Specimen | Used for | Licence |
|---|---|---|---|
| FlyWire FAFB v783Dorkenwald et al. 2024; Schlegel et al. 2024, Nature | adult female, brain | brain circuit of the fly model | CC BY-NC 4.0 |
| MaleCNS v1.0Berg et al. 2025, bioRxiv; FlyEM, HHMI Janelia | adult male, brain + nerve cord | locomotor nerve cord of the fly model; anatomy explorer | CC BY 4.0 |
| BANC v888Bates et al. 2026, Nature | adult female, brain + nerve cord | anatomy explorer and films; the single-animal model in development | CC BY 4.0 |