003 — PING Stimulus Overdrive Video
Abstract
PING — Pyramidal-Interneuron Network Gamma — emerges when excitatory (E) and inhibitory (I) populations drive each other: E fires, recruits I, I silences E, I decays, E fires again. The cycle repeats at 30–80 Hz, but only when E gets enough external drive; below threshold the network sits in background firing. This notebook is the basic drive-threshold scan — companion sweeps live in nb005 (integration step) and nb006 (E→I coupling strength). See The Notebooks for how this entry’s runner/artifact/figure triple is wired up.
Methods
A scan over the oscilloscope video subcommand: each frame is a fresh 600 ms simulation on MNIST digit 0, sample 0. The stim window (200–300 ms) multiplies the Poisson input rate by the overdrive factor shown on the frame; the sweep walks overdrive 1× → 10× over 300 frames. All knobs are hardcoded literals in src/pinglab/notebooks/nb003.py per the runner contract.
| Parameter | Value |
|---|---|
| Setup | |
| Model | ping |
| Input | mnist d0 s0 @ 50 Hz max |
| Seed | 42 |
| Architecture | |
| N_E / N_I | 512 / 128 |
| dt / T | 0.1 / 600 ms |
| Stimulus & scan | |
| Stim window | 200–300 ms |
| Overdrive scan | 1×–10× |
| Frames / FPS | 300 / 30 |
| Provenance | |
| Tier | large |
| Elapsed | 37m 43s |
| Run ID | r013 |
| Git SHA | ? |
Results
Each frame is a fresh 600 ms sim on MNIST digit 0, sample 0. The stim window (200–300 ms) multiplies the Poisson input rate by the overdrive factor shown on the frame; the sweep walks overdrive 1× → 10× over 300 frames.
In Figure 1 three regimes emerge: async baseline (1–1.2×), unstable PING onset (1.2–6×), stable PING (6×–onwards).
Population rates
| Window | E (Hz) | I (Hz) |
|---|---|---|
| Pre-stim | 6.8 | 0.0 |
| In-stim | 15.5 | 35.5 |
| Post-stim | 5.6 | 0.0 |
Discussion
TODO: discussion paragraph — write what the results above mean for the project.
Next steps
The threshold around overdrive ≈ 1.2× is sharp on this MNIST sample but the structure depends on input statistics; a sample-averaged version (mean rate envelope across many digits) would harden the regime boundaries. With the threshold map in hand, nb005 and nb006 hold drive fixed in stable-PING territory and sweep the other two knobs (dt, ei-strength) — together the three videos pin the working-point box for every training entry downstream.
Appendix
Reproduction
uv run src/pinglab/notebooks/nb003.py