fill vs refill

2026-06-19 14:09:24 +02:00
parent e807c77dad
commit 4c6c956345
2 changed files with 60 additions and 16 deletions
@@ -242,3 +242,35 @@ of the whole synapse.
 ### Shockwave lockdown
 Emergency global astrocytic Ca²⁺ wave → GABA + ATP release → mass AMPA internalization and
 hyperpolarization. Bypasses budget gates. A circuit breaker against runaway excitation.
+
+---
+
+## Pool-filling: private reserve vs contested supply
+
+The pseudocode uses two filling primitives, distinguished by where the resource comes from.
+
+**`fill` (private reserve).** The pool is replenished from a source the component owns
+outright, uncontested by siblings, bounded by the component's own ceiling and a rate cap.
+- RRP refill — vesicles mobilized from the bouton's own reserve pool toward the docking-slot
+  ceiling, rate-limited by VATPase. The reserve is private to the bouton.
+- SOMA self-replenish — the soma fuels itself from its own mitochondria toward its budget
+  ceiling. No other component draws on it.
+
+**`refill` (contested supply).** The pool is replenished from a supply that multiple
+components compete for, rationed by demand (gap to ceiling).
+- pre/post/dend/axon budgets — drawn from astrocytic lactate (shared across all synapses the
+  astrocyte wraps) plus shipment from soma/axon/dendrite (shared across downstream targets).
+
+**Neither primitive (their own forms).** Some inflows are not fills toward a ceiling:
+- AMPA surface insertion — Ca²⁺-driven rate from the spine's private endosomal reserve, with
+  an explicit passive drift-back (short-term depression) when Ca²⁺ is low. Not a steady fill.
+- D-serine release — demand-driven (saturating in astro Ca²⁺) and budget-limited, like NT
+  release; a release process, not a pool top-up.
+- Root productions — `glycolysis(glucose)` at the astrocyte and `CREB_synth(soma_tag)` at the
+  soma are the system's energy and material roots: raw inflows capped only by the external
+  vascular supply, not fills toward an internal ceiling.
+
+The distinction matters biologically: a private reserve guarantees a component some autonomy
+(the bouton can refill its RRP from its own vesicles even when lactate is scarce), while a
+contested supply couples a component's fate to its neighbours' demands (operational budget
+fails first where many active synapses compete for the same lactate).