# Phase 4AC — LIF semantics and unchanged-dynamics motif audit

Status: COMPLETE-SEMANTICS-AUDIT / LEARNING-NOT-ACHIEVED.
No alternative dynamics deployed to MaleCNS; no conditioning, learned candidate or new formal runtime.

## Author model versus frozen adapted model

Pinned author model resets g on a spike and declares v/g `(unless refractory)`, uses linear integration, strict > threshold and voltage Poisson input with zero refractory on stimulated cells.
The frozen adapted model retains g, decays/accepts events during refractory, uses explicit Euler and >= threshold, and forced sensory spikes respect refractory.
These are documented model choices, not a newly established GPU regression. g is an additive voltage-valued drive, not a measured conductance.
W_syn=0.275 is transferred from a free parameter calibrated in the original FlyWire feeding model, not a measured universal MaleCNS synaptic efficacy.

## Synthetic single-cell component tests

All impulse amplitudes derive from the complete unique contact counts of the predeclared 13 real motif edges plus a one-contact fixture; other boundary/sustained cases are explicitly synthetic unit tests.
These ablations retain frozen Euler arithmetic/scheduling and are NOT complete Brian2 replication. No successful amplitude or policy was selected after seeing results.

| Single-impulse fixture | Frozen | Reset g only | Refractory gate only | Reset + gate |
|---|---:|---:|---:|---:|
| one_impulse_contacts_1 | 0 | 0 | 0 | 0 |
| one_impulse_contacts_104 | 0 | 0 | 0 | 0 |
| one_impulse_contacts_172 | 1 | 1 | 1 | 1 |
| one_impulse_contacts_210 | 1 | 1 | 1 | 1 |
| one_impulse_contacts_226 | 1 | 1 | 1 | 1 |
| one_impulse_contacts_235 | 1 | 1 | 1 | 1 |
| one_impulse_contacts_259 | 1 | 1 | 1 | 1 |
| one_impulse_contacts_283 | 1 | 1 | 2 | 1 |
| one_impulse_contacts_43 | 0 | 0 | 0 | 0 |
| one_impulse_contacts_57 | 0 | 0 | 0 | 0 |
| one_impulse_contacts_64 | 0 | 0 | 0 | 0 |
| one_impulse_contacts_70 | 0 | 0 | 0 | 0 |
| one_impulse_contacts_76 | 0 | 0 | 0 | 0 |
| one_impulse_contacts_95 | 0 | 0 | 0 | 0 |

Reset-only and combined policies can produce at most one spike from a single isolated input by construction. This does not establish biological correctness or whole-brain learning improvement.

## Real anatomical motifs — frozen mathematics ONLY

One forced seed spike at step 0 except the no-input control; no subsequent input; observed for 1 s. Late window=500–1,000 ms.
The recurrent pair/trio/five are induced subgraphs. The feedforward control selects four existing edges and removes feedback only within this isolated diagnostic harness.
External inhibition, graded APL and other whole-brain inputs are absent. A sustained isolated motif is evidence of sufficiency in this harness, NOT necessity in the complete brain.

| Motif | neuron_idx | Total spikes | Late spikes | Last ms |
|---|---:|---:|---:|---:|
| pair | 1381 | 237 | 119 | 999.3 |
| pair | 1511 | 236 | 119 | 997.5 |
| trio | 1197 | 355 | 179 | 999.3 |
| trio | 1381 | 355 | 178 | 997.8 |
| trio | 1511 | 354 | 178 | 997.4 |
| five | 1197 | 370 | 185 | 998.8 |
| five | 1381 | 369 | 185 | 997.4 |
| five | 1511 | 367 | 186 | 999.5 |
| five | 82312 | 80 | 41 | 990.3 |
| five | 133666 | 297 | 150 | 999.5 |
| feedforward | 1197 | 1 | 0 | 10.0 |
| feedforward | 1381 | 1 | 0 | 0.0 |
| feedforward | 1511 | 1 | 0 | 4.9 |
| feedforward | 82312 | 0 | 0 | none |
| feedforward | 133666 | 0 | 0 | none |
| no_input | 1197 | 0 | 0 | none |
| no_input | 1381 | 0 | 0 | none |
| no_input | 1511 | 0 | 0 | none |
| no_input | 82312 | 0 | 0 | none |
| no_input | 133666 | 0 | 0 | none |

## Verification and boundaries

Seven unit tests; all five real motifs CPU/GPU event, count, final V/g/refractory, queue and timestep history exact; five archived deterministic-v2 full-brain trials exact.
Every selected edge_id, source CSR row, destination and original weight validated; generated prepared inputs hashed. All original snapshot files and Phase 4AA/4AB model/experiment manifests checked before and after.
Diagnostic wall time including compilation and observation: 95.398 s. Peak allocated process VRAM: 285994496 bytes. Not a runtime-speed benchmark.
Original author code was inspected, not executed; no Brian2 oracle run and no new package installation. ComfyUI was not stopped or unloaded.

## Decision

The usable-learning gate remains unmet: independent evaluation, A-vs-neutral-B specificity in MBON/downstream, multiple training seeds and conditioning controls still required.
Before any full-network alternative, obtain explicit separate model authorization and distinguish each semantic component; do not claim g reset alone reproduces the author implementation.
No evidence here permits changing eta, thresholds, gain, frozen APL calibration, transmitter signs or the plastic mask.

## Primary provenance

[Shiu et al. 2024](https://www.nature.com/articles/s41586-024-07763-9)
[Pinned author implementation](https://github.com/philshiu/Drosophila_brain_model/blob/91bdd1e7dcf193f3e7ca5a8933497fcef63b7960/model.py)
Downloaded source, MIT license, environment specification, exact commit, SHA-256 and source clauses retained under external-resources and audit.