no ecb messages

elements/neuron/appunti/2026-06-19-biological-reference-v10.md

@@ -274,3 +274,60 @@ The distinction matters biologically: a private reserve guarantees a component s
 (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).
+
+---
+
+## PRE ↔ POST interaction: local computation, message-only coupling
+
+The presynapse and postsynapse never read each other's internal state. They interact only
+by writing to and reading from shared cleft channels. Each side computes entirely locally on
+what it has: its own variables plus whatever signals have arrived in the cleft. This is the
+message-passing realization of the locality principle.
+
+**Forward channel — glutamate (PRE → POST and ASTRO).** The presynapse writes glutamate via
+NT_flux. The postsynapse reads it (AMPA, NMDA) and the astrosynapse reads it (clearance,
+mGluR5). The astrosynapse clears it. PRE never knows whether POST responded — it only emits.
+
+**Gate channel — astro_Dserine (ASTRO → POST).** The astrosynapse writes D-serine; the
+postsynapse reads it as the obligatory NMDA co-agonist. POST cannot open NMDA without this
+arrived signal, but it does not read the astrocyte's state — only the delivered D-serine.
+
+**Backward channel + — retro_NO (POST → PRE).** When the postsynapse's NMDA opens (Mg²⁺
+ejected, D-serine present, glutamate bound), nNOS — physically tethered to the NMDA receptor
+through PSD-95 — synthesises nitric oxide (and, on a slower timescale, BDNF is released).
+These diffuse retrogradely to the presynapse. Biologically this is the classic retrograde
+messenger of LTP: it tells the bouton that its release landed on a postsynapse that genuinely
+responded. In the model, POST emits `retro_NO` proportional to its own NMDA-driven calcium —
+computed purely from POST's local state — and PRE reads it as `retro_NO_local`.
+
+  `retro_NO_local` is exactly the grounding of the presynaptic endurance signal. The
+  presynapse's local success proxy is "I was releasing strongly" (`pre_fast_trace` high). On
+  its own that only says the bouton was working hard, not that the work mattered. `retro_NO`
+  adds the missing confirmation — that the postsynapse responded — without PRE ever reading
+  POST's calcium. So PRE deposits endurance need as `pre_fast_trace × (1 + retro_NO_local)`:
+  strong release that was confirmed effective makes the strongest claim that fuel, not
+  futility, was what interrupted a forming success. retro_NO is short-lived (NO degrades and
+  diffuses within seconds), so the channel decays fast — confirmation must be recent to count.
+
+**Backward channel − — retro_eCB (POST → PRE).** When the postsynapse is strongly
+depolarised, it synthesises endocannabinoids (2-AG, anandamide) that diffuse retrogradely and
+bind presynaptic CB1 receptors, suppressing release. This is depolarisation-induced
+suppression of excitation (DSE) — a homeostatic negative feedback: an over-driven postsynapse
+tells the presynapse to release less. In the model, POST emits `retro_eCB` from its own
+membrane potential, and PRE reads it as `retro_eCB_local`, which reduces the release drive
+`sat(...) × (1 - retro_eCB_local)`. Again POST computes from its own state; PRE adjusts from
+the arrived signal; neither reads the other's interior.
+
+The two backward channels are opposite-signed messages the postsynapse sends about its own
+condition: retro_NO says "your input was effective — worth sustaining," retro_eCB says "I am
+saturated — ease off." Together with the forward glutamate and the D-serine gate, they make
+the synapse a fully message-coupled system of locally-computing components.
+
+**Why RRP refill is in NOT_AP only.** During an AP the bouton releases — RRP depletes. Refill
+(VATPase reloading vesicles from the reserve pool) is a recovery process that proceeds between
+spikes. Placing `fill(RRP, ...)` only in the NOT_AP context makes the AP context pure
+depletion and the NOT_AP context pure recovery. A consequence falls out for free: during
+sustained high-frequency firing there are many AP steps and few NOT_AP steps, so RRP depletes
+faster than it recovers — short-term depression deepens with frequency, with no explicit
+depression rule. The release itself is throttled further when budget is low (VATPase refill
+is energy-limited), coupling metabolic state to the depth of depression.

elements/neuron/appunti/2026-06-19-tripartite-synapse_v10.md

@@ -30,6 +30,13 @@ NIGHT variables
 LOCALITY RULE
   every evaluation uses only local state + signals that have arrived.
   no component reads another compartment's internal state.
+
+CLEFT MESSAGE CHANNELS (the only PRE/POST/ASTRO interaction — each writes, others read)
+  glutamate     PRE → POST, ASTRO     (forward transmitter; cleared by ASTRO)
+  astro_Dserine ASTRO → POST          (NMDA co-agonist gate)
+  retro_NO      POST → PRE  (+)       (NO/BDNF: "release reached a responsive target")
+  retro_eCB     POST → PRE  (−)       (endocannabinoid: "over-driven, suppress release" = DSE)
+  Each channel decays/clears; a component reads a channel into a local copy and computes locally.
 ```
 
 ---
@@ -46,7 +53,7 @@ sat(x, K) = x / (K + x)
 
 ```
 K_release  K_AMPA  K_Dserine
-Mg_eject   Ca_STP   Ca_TAG
+Mg_eject   Ca_STP   Ca_TAG   eCB_thr
 elig       dop_thr  tag_thr  tag_expiry
 traj_thr   endur_thr
 spillover  inactivation  overload
@@ -96,24 +103,34 @@ that neighbours compete for.
 ## PRE
 
 ```
+// Backward messages from POST (computed by POST from its own local state, read here):
+//   retro_NO  (+) : POST responded — release reached a responsive target
+//   retro_eCB (−) : POST over-driven — suppress release (DSE)
+// PRE reads these as arrived signals; it never reads POST's internal state.
+
 DAY | AP:
     if pre_budget < release_cost:
         suppress(NT_flux)
-        if pre_fast_trace > traj_thr:                    // LOCAL success: I released strongly
+        // interrupted LOCAL success: I was releasing strongly (own fast_trace),
-            pre_endurance_need += pre_fast_trace × (1 + retrograde_local)
+        // confirmed by retro_NO that POST actually responded
+        if pre_fast_trace > traj_thr:
+            pre_endurance_need += pre_fast_trace × (1 + retro_NO_local)
         exit
     pre_fast_trace += spike_Ca(input_freq);  pre_fast_trace *= decay(100ms)
-    drive = sat(pre_fast_trace, K_release)
+    drive = sat(pre_fast_trace, K_release) × (1 - retro_eCB_local)   // DSE brake from POST
     if RRP > 0:
         NT_flux   = RRP × drive
         glutamate += NT_flux·Δt;  RRP -= NT_flux·Δt;  pre_budget -= NT_flux·fusion_cost
-    fill(RRP, pre_structure.slot_ceiling, pre_structure.refill_ceiling, vatpase_cost, pre_budget)
+    if glutamate > spillover: drive *= brake                // autoreceptor/astro brake (output)
-    if glutamate > spillover: drive *= brake             // output brake (not a fill)
+    // NO fill here — AP only depletes RRP; recovery happens in NOT_AP
+    // (sustained high-frequency firing therefore deepens short-term depression)
 
 DAY | NOT_AP:
     pre_fast_trace *= decay(100ms);  pre_endurance_need *= decay(min)
-    refill(pre from astro_lactate[syn] + axon_ship_pre)  // contested: lactate + shipment
+    retro_NO_local  = retro_NO;   retro_NO  *= decay(s)     // receive + channel clears (NO short-lived)
-    fill(RRP, pre_structure.slot_ceiling, pre_structure.refill_ceiling, vatpase_cost, pre_budget)
+    retro_eCB_local = retro_eCB;  retro_eCB *= decay(s)     // receive + channel clears
+    refill(pre from astro_lactate[syn] + axon_ship_pre)     // contested: lactate + shipment
+    fill(RRP, pre_structure.slot_ceiling, pre_structure.refill_ceiling, vatpase_cost, pre_budget)  // private reserve
     if pre_fast_trace > elig: pre_possible_tag += pre_fast_trace
     pre_possible_tag *= decay(s);  dopamine *= decay(ms)
     if dopamine > dop_thr and pre_possible_tag > tag_thr:
@@ -137,6 +154,13 @@ DAY | NOT_bAP:
     // SOURCE 2 — NMDA: large Ca if local coincidence
     if Vm > Mg_eject and astro_Dserine > thr and glutamate > 0:
         post_fast_trace += NMDA_Ca(glutamate)·rise_speed();  post_budget -= NMDA_cost
+        retro_NO += NO_emit(post_fast_trace);  post_budget -= NO_synth_cost
+        // POST → PRE (+): nNOS coupled to NMDA emits NO/BDNF — "your release was effective"
+
+    // backward brake to PRE (−): strong depolarization → endocannabinoid (DSE)
+    if Vm > eCB_thr:
+        retro_eCB += eCB_emit(Vm);  post_budget -= eCB_synth_cost
+        // POST → PRE (−): "I am over-driven — reduce release"
 
     post_fast_trace *= decay(ms)