New · the Habitat
Play
Look after a fly with connectome-based neural circuits. Feed it, discover its modelled behaviours and the neurons behind them, cross fly lines, shape its terrarium.
In-silico laboratory · fly model
Meet a fly whose brain is wired from real data.
NeuroCause runs nervous systems on their measured wiring. Look after the fly in a game, or run the experiments a lab would: explore a model linking 7,270 mapped brain neurons to senses, a body and a nerve-cord circuit. Watch its activity, change an input, and investigate the response.
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.
7,270brain neurons from the adult female FlyWire connectomeFAFB v783 · measured
784,219signed connections, weighted by measured synapse countspair × neuropil · measured
1,045nerve-cord neurons driving six legsMaleCNS v1.0 · measured
1 msneural time step; sensing, brain, body and feedback close at 120 Hzmodel
36automated test suites, all passing for release 2.5verification
Two ways in
Play with the fly. Or experiment on it.
Both run the same model in the same application, on your own device. The game makes the science tangible; the laboratory makes it testable.
The laboratory
Experiment
Run ten assays from the fly literature, silence or activate identified cells, record every rate, and trace each behaviour through the model's pathways. Export the seed, parameters and run record to check reproducibility.
New in 2.5 · the Habitat
A small world. A connectome to explore.
Feed the fly, and its taste circuit decides whether it drinks. Every behaviour you see for the first time becomes a card naming the neurons that decided it, with their measured wiring. Care values, leaves and ranks are game rules and say so; everything the fly does is the simulation.
- Discover thirteen behaviours and eighteen neuron cards, each with the paper behind it and lit up in the 3D brain.
- Cross fly lines as real labs do, GAL4 drivers with UAS effectors: silence the giant fiber and the fly no longer escapes; warmth starts a moonwalk.
- Shape the terrarium with ferns, flowers, stones and logs. The fly's eye sees them; solid pieces are in the way.
- Take photos captioned by the model, and follow quests drawn from real assays.
- Watch and hear a decision (new in the browser version): replay the half second around an escape twenty times slower, listen to a neuron's spikes as clicks, and see the fly's brain light up above it as it moves.
- Ask the big question: the eight sentience criteria, explored in your own fly. The answer is a map, not a score.
Play the Habitat now Free, in your browser or on your phone. Your progress stays on your device.
How it works
Measured wiring. Stated models. Traced causes.
A connectome records reconstructed connections and synapse counts, not a complete measurement of physiological strength or activity over time. NeuroCause uses selected circuits from these datasets and documents the assumptions needed to turn their anatomy into a running model.
Measured
Anatomy from electron microscopy
Cell identities, positions and reconstructed contacts come from published connectome releases, with source licences and file fingerprints. Circuit extraction, predicted transmitter signs and model-specific calibrations are documented in the methods.
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
Follow the model's pathways
Inspect inputs, firing rates and synaptic drive behind a model response. Traces help form a hypothesis; silencing, controls and repeated trials test dependence within the model. They do not by themselves validate a cause in a living fly.
The laboratory
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.
Models and vision
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 2.5
Three fly models
The reference fly: 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. Beside it, a male and a female fly whose brain and nerve cord come from one animal each (MaleCNS v1.0, BANC v888), with documented calibrations.
In preparation
Comparison connectomes
The male nerve cord (MANC) and the male optic lobe are in the anatomy explorer, each kept as its own specimen. A cell type found in several animals lets an assay ask whether a result depends on the individual whose wiring was measured.
Vision
What would it take for one to feel?
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.
The research record
The methods.
The methods.
The limits.
In the open.
Our public working paper traces every layer from reconstructed synapses to modelled dynamics, shows negative results and sets out what must be tested before stronger biological claims can be made.
NeuroCause / Research SoftwareMethods &
validation status
validation status
Working paper · version 0.3
28 September 2026
Not peer reviewed
The connectome in motion
One animal, from brain to nerve cord
Six short films of the BANC connectome — a complete brain-and-cord wiring diagram of a single female fly, and the dataset behind our female 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.
Get NeuroCause
In your browser, on Windows and on Android · release 2.5
The application with the fly model, free and without advertising: in a current browser, for Windows 10 and 11 (64-bit) and for Android phones and tablets. Because the FlyWire brain data carries a non-commercial licence, it is and remains free of charge. The software terms apply to every version: the Windows and Android apps ask you to accept them before they start, the browser version applies them when you use it.
In your browser
Nothing to install: the same application in a current browser on a computer, tablet or recent phone. It downloads about 6 MB, computes everything on your device and keeps your progress there.
Windows, portable
Release 2.5.0 as a ZIP of about 183 MB. Unzip it anywhere and start NeuroCause.exe; nothing is installed
and nothing connects to the internet. Settings from earlier versions carry over.
Android, APK
Release 2.5.0 for Android 7.0 or newer with OpenGL ES 3.0, about 28 MB. Open the file on your phone or tablet; Android asks once to allow installs from your browser or file manager. The app runs entirely on the device and connects to nothing.
Early access
Support and get invited
Want the next version before everyone else?
People who support NeuroCause may be invited to test new versions before their public release. A one-time contribution of any amount, through Stripe, without an account. How it works
New in 2.5
- The Habitat. A care, discovery and fly-genetics game played with the simulated fly itself: quests, a field journal of behaviours and neuron cards with measured wiring, crosses whose offspring run with their genotype, a terrarium you shape, photos, and the eight sentience criteria. On phones it sits in the bottom bar.
- Stricter causal chains. Dust, a loom or a burst from the Stimulate panel is named as the cause of a behaviour only if its own receptors reached the deciding neurons; behaviour driven by virtual genetics now names the genetics.
- New in the world. Objects can be added to and removed from the terrarium (never right in front of the fly), each change written to the experiment journal.
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. Using it in research or a course? Write to us.
How to use the fruit fly brain simulator
Your first few minutes
Start curious. You do not need to be a neuroscientist.
One application, two ways to explore. No account or donation is needed to begin.
Meet the fly
Open Habitat and let the model load. A short tour shows what you can do. Then follow the first quest and watch what the fly does before changing anything.
Open Habitat →Offer. Observe. Ask why.
Try feeding, then inspect the response and the neuron cards. No response is informative too: behaviour depends on the circuit and its current conditions.
Understand the model →Turn curiosity into a test
Choose a guided assay in the Lab. Compare conditions, inspect the statistics and export the results together with their model context.
Open the Lab →
Which version should I use?
The browser is the quickest way to try NeuroCause. Windows and Android downloads run locally without a network connection after installation. A recent browser with WebGL 2 is needed for the web version; close other demanding tabs if it feels slow. Choose your version.
Will my fly and progress follow me to another device?
Progress is stored locally, not in an account. It does not automatically transfer between browsers, phones or the installed app. Clearing site data or using private browsing can remove it. Keep a backup using Habitat's export option where supported, and import it on the other device.
Is this a living fly or a validated drug-testing system?
It is a computational model constrained by measured anatomy. Neural dynamics, sensory input, body mechanics, virtual genetics and game progression include modelling assumptions. Subjective experience is not established, and the current system is not a validated replacement for animal experiments or clinical drug testing. See the evidence and limits.
Do I need to donate to play or do research?
No. The available game and laboratory features are free to use under the software and data terms. Contributions are optional, one-time payments through Stripe. Supporters may be invited to pre-release testing; an invitation is not guaranteed.
Support NeuroCause
Help make the next experiment possible.
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. Your contribution supports the computing and careful validation behind each release.
- Early access: supporters may be invited to try pre-releases before anyone else
- Computing power for simulation runs, validation and films rendered from the models
- New assays and models, each checked against the published literature
- Open access for researchers, educators and curious adults, without ads or accounts
One-time contribution
Choose what to give.
Set your amount in CHF on Stripe’s secure checkout. There is no account to create here and the software stays free whether or not you contribute.
Choose an amount on StripeYou will leave NeuroCause for Stripe before entering payment details. No payment is taken on this page.
Supporter perk
Try what comes next, first. People who contribute may be invited to test new NeuroCause versions before their public release, by email to the address given at checkout. How it works
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
Data
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 | nerve cord of the reference fly; brain and nerve cord of the male fly; anatomy explorer | CC BY 4.0 |
| BANC v888Bates et al. 2026, Nature | adult female, brain + nerve cord | brain and nerve cord of the female fly; anatomy explorer and films | CC BY 4.0 |