# Phase 4Z: event-resolved PN feedback and input acceptance

This diagnostic stage follows user approval to investigate upstream feedback and delivered-input differences. All historical inputs and model files remain read-only. No learning, gain adjustment, changed thresholds, novel transmitter sign, mask expansion or game interface is permitted.

## Registered scope

Replay six old calibration odors with seed 131101 under the two existing Phase 4Y conditions: frozen reference and diagnostic DPM fast-current-off. This is reproduction of a sealed intervention, not promotion of it. Only that previous in-memory effective-current overlay is allowed. Save outputs in new Phase 4Z directories. Preserve current delay/refractory and request acceptance semantics. Do not force a matched delivered spike train by overriding refractory state.

Observer targets are KC 82312, every actual annotation-ALPN input to it, and ALLN nodes 1197/1381/1511 found on a prior Phase 4W time-supported ancestry. Selection is exploratory and explicitly based on prior outcomes. Do not call it blind validation or unique-cause identification.

Use exact incoming-edge event reconstruction and CPU single-cell replay to verify queue, V/g, natural spikes, output spikes and accepted requests. Conditional omissions retain other measured arrivals and APL; they are not closed-loop whole-brain ablations. Distinguish anatomical recurrence, event-supported recurrence and experimentally demonstrated necessity.

Reference reproduction must match Phase 4Y counts, final V/g, trace and KC events. Frozen-reference whole-brain events must additionally match Phase 4W. Repeat both first-odor conditions and rerun five frozen deterministic reference trials. Abort result generation on any mismatch; do not repair frozen data. Hash history and all new final artifacts.

## Literature context, not parameter authority

- Eckstein et al., Cell 2024, doi:10.1016/j.cell.2024.03.016: DPM dopamine predictions in FlyWire/hemibrain identified as mispredictions. This is not direct ground truth for the two MaleCNS bodies. https://pmc.ncbi.nlm.nih.gov/articles/PMC11106717/
- Haynes et al., eLife 2015, doi:10.7554/eLife.03868: DPM GABA/serotonin-related physiology; does not provide a universal MaleCNS edge-specific current model. https://pmc.ncbi.nlm.nih.gov/articles/PMC4305081/
- Hu et al., PNAS 2010, doi:10.1073/pnas.0914912107: functional mushroom-body-to-antennal-lobe feedback. Existence of such feedback does not prove the current residual loop traverses KC/MBON. https://pubmed.ncbi.nlm.nih.gov/20479249/
- Localized inhibition in the Drosophila mushroom body, 2020: spatially localized APL inhibition. No changes to frozen APL parameters are authorized here. https://pmc.ncbi.nlm.nih.gov/articles/PMC7541083/
- Shiu et al., Nature 2024, doi:10.1038/s41586-024-07763-9: sensorimotor LIF model, not universal validation of associative-memory physiology. https://pmc.ncbi.nlm.nih.gov/articles/PMC11446845/

No slow receptor time constants, biological sign correction or parameter tuning is derived from these citations. Source code SHA-256 serves as this audit's reproducible version identifier.