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encephagen

A functional miniature human brain — 19,200 spiking neurons, real connectome topology, learns from experience.

python interact.py
brain> look A          → visual cortex activates, signal propagates through connectome
brain> teach A         → pair pattern A with reward, brain learns the association
brain> test            → trained pattern produces stronger response than novel ones
brain> memory A        → show pattern, remove it — PFC maintains the trace (75% persistence)
brain> sound           → auditory cortex activates
brain> touch           → somatosensory cortex activates
brain> status          → see all 12 brain regions firing in real-time

What This Brain Can Do

Function Status How
See 56% accuracy at 5 patterns (2.8x chance) Visual cortex processes input, distinct responses per pattern
Learn (e-prop) Connectome outperforms random on conditioning (p=0.011) Eligibility traces + surrogate gradient + reward modulation
Remember 75% PFC persistence after stimulus removal NMDA slow synapses (tau=150ms) sustain prefrontal activity
Learn Classical conditioning, stimulus-specific Three-factor STDP: pre x post x reward strengthens pathways
Predict Trained stimuli trigger stronger responses Learned associations persist, novel stimuli produce weaker response
Integrated See, remember, learn, predict in one task All cognitive functions work together through the connectome

Architecture

19,200 LIF spiking neurons across 96 brain regions
Connected by real Human Connectome Project structural connectivity (TVB96)
GPU-accelerated (PyTorch sparse operations)

Cognitive regions:
  Visual cortex      1,600 neurons  (pattern recognition)
  Prefrontal cortex  4,000 neurons  (working memory with NMDA slow synapses)
  Temporal cortex    2,000 neurons  (semantic processing)
  Parietal cortex    1,600 neurons  (spatial/attention)
  Hippocampus          800 neurons  (associative memory)
  Amygdala             400 neurons  (reward learning, conditioning)
  Basal ganglia      1,200 neurons  (action selection)
  Thalamus           1,200 neurons  (relay, gating)
  Motor cortex       1,600 neurons  (output)
  Cingulate cortex   2,000 neurons  (conflict monitoring)
  Somatosensory        800 neurons  (touch)
  Auditory             800 neurons  (hearing)

Quick Start

git clone https://github.com/toroleapinc/encephagen.git
cd encephagen
pip install -e ".[dev]"

# Interactive session
python interact.py

# Or run experiments:
python experiments/15_conditioning.py         # Classical conditioning
python experiments/16_pattern_recognition.py  # Pattern recognition
python experiments/17_working_memory.py       # Working memory
python experiments/18_integrated_cognition.py # All together

How It Works

Neurons: Leaky Integrate-and-Fire (LIF) with separate AMPA (fast, tau=5ms) and NMDA (slow, tau=150ms) synaptic currents. NMDA only in PFC for working memory persistence.

Connectivity: Real structural connectivity from the Human Connectome Project (diffusion MRI tractography, 96 regions). Between-region connections follow actual white matter fiber pathways.

Learning: E-prop (Bellec et al. 2020) — eligibility traces per synapse track causal influence of weight on spiking via surrogate gradient. Reward modulates snapshotted eligibility for temporal credit assignment. Also supports simpler three-factor Hebbian for comparison.

Working Memory: NMDA-like slow synaptic dynamics in prefrontal cortex create persistent activity after stimulus removal (Compte et al. 2000, Wang 2001).

All Experiments

# Experiment Result
1-4 Wilson-Cowan phase 1 Two-level decomposition: degree drives hierarchy, wiring drives FC patterns
5 Spiking hierarchy Sensory > thalamus > motor > BG > PFC (matches Murray et al. 2014)
6 STDP habituation Repetition suppression detected
7-9 Embodied learning Invalidated by controls (motor death, not learning)
10 Pendulum learning 5 approaches failed (research frontier)
11 Spontaneous body Emergent rhythmic twitching, corrective responses from topology
12-13 Brain + spinal CPG + body 0.98 Hz alternating gait, brain modulates walking speed
14 Crawling worm 0.31m forward displacement in 10s
15 Classical conditioning Brain learns stimulus-reward association, stimulus-specific
16 Pattern recognition 56% accuracy at 5 classes (chance=20%)
17 Working memory 75% PFC persistence with NMDA synapses
18 Integrated cognition See + remember + learn + predict — all working
19-20 Walker2d body control Brain keeps unstable body upright 1.4s (vs 1.0s zero)
21 Connectome vs random (Hebbian) Structure creates organization (p=0.0002) but not cognitive advantage
22 Connectome vs random (e-prop) Structure helps conditioning (p=0.011) — e-prop reveals advantage Hebbian missed

Relation to Prior Work

Project What they did How we differ
Spaun (Eliasmith 2012) 2.5M neurons, 8 cognitive tasks, hand-designed Real human connectome, STDP learning (not pre-computed weights)
Gollo et al. 2015 Timescale hierarchy from identical oscillators Extended to spiking neurons + cognitive functions
Zamora-Lopez & Gilson 2025 Wilson-Cowan regional diversity Added learning, memory, and interactive interface
OpenWorm 302-neuron C. elegans, emergent locomotion Human connectome, cognitive focus, 19K neurons

Important Caveats

This project uses diffusion MRI tractography data (TVB96), not synaptic-resolution connectomics. The 96-region parcellation is macro-scale. Effects are real but small. Embodied learning does not yet work (STDP produces motor death). The Wilson-Cowan and spiking models give opposite hierarchies (unexplained). See RDR-2026-04-01.md for full documentation including negative results and expert reviewer feedback.

Data

Structural connectivity from The Virtual Brain (TVB96: 80 cortical + 16 subcortical regions), derived from Human Connectome Project diffusion MRI tractography.

Contributing

Contributions welcome, especially:

  • Stronger working memory (attractor dynamics, longer NMDA time constants)
  • Better pattern recognition (STDP-trained visual hierarchy)
  • Embodied learning that actually works (e-prop, three-factor rules)
  • Web-based interactive interface
  • Performance optimization for real-time interaction

Citation

@software{encephagen2026,
  title={encephagen: A functional miniature human brain simulation},
  author={edvatar},
  year={2026},
  url={https://github.com/toroleapinc/encephagen}
}

Related Projects

  • conntopo — Connectome dynamics vs null models toolkit
  • cortexlet — Brain-topology trainable neural network

License

MIT

About

Does human brain structure produce emergent functional organization? Miniature brain simulation with identical parameters everywhere — regions develop distinct roles purely from connectome topology.

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