Update 2026-06-02-astrocyte-behaviors.md

elements/astrocyte/appunti/2026-06-02-astrocyte-behaviors.md

@@ -96,6 +96,170 @@ Operating high-fidelity wave generators and vibrating resonators drains the syst
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+# Pseudocode, organized by variable, influence, and time
+
+## global state variables
+
+// ─── FAST (ms–s) ─── INTERMEDIATE (s–min) ─── SLOW (h–days) ───
+
+// Presynaptic
+vesicle_release_prob // P(0.1–1.0) — baseline 0.2
+active_zone_size // docking slots — scales launchpad
+RRP_pool // readily-releasable pool (fast)
+reserve_pool // chained vesicles in deep storage
+presynaptic_Ca // [Ca²⁺] at active zone
+
+// Postsynaptic
+AMPA_count // surface receptors = sensitivity
+NMDA_Mg_block // bool — mechanical clamp on/off
+postsynaptic_Ca // [Ca²⁺] in spine — triggers LTP/LTD
+membrane_potential // Vm — depolarization state
+
+// Astrocyte
+glutamate_clearance_rate // EAAT transporter speed
+D_serine_release // gliotransmitter — NMDA co-agonist
+astro_Ca // internal Ca²⁺ wave state
+ECM_integrity // extracellular matrix density
+lactate_output // fuel export rate to neurons
+
+// Neuromodulators (global broadcast)
+dopamine_level // "save button" — validates LTP
+norepinephrine_level // arousal / signal-to-noise gain
+acetylcholine_level // attention — lowers LTP threshold
+
+## fast time scale — wave propagation (ms → s)
+
+function fire_action_potential(input_freq):
+
+// Presynapse: launch wavefront
+presynaptic_Ca += spike_influx(input_freq)
+released_vesicles = binomial(RRP_pool, vesicle_release_prob)
+glutamate_cleft = released_vesicles × quantal_content
+RRP_pool -= released_vesicles
+
+// Postsynapse: wavefront strikes resonator
+AMPA_current = glutamate_cleft × AMPA_count
+membrane_potential += AMPA_current
+
+// NMDA gate — needs coincidence (clamp check)
+if membrane_potential > -40mV and D_serine_release > threshold:
+NMDA_Mg_block = False // Mg²⁺ ejected — clamp unlocked
+postsynaptic_Ca += NMDA_influx(glutamate_cleft)
+
+// Astrocyte: vacuum up trailing echoes
+glutamate_cleft -= glutamate_clearance_rate × Δt
+lactate_output += glycolysis_rate(glutamate_clearance_rate)
+
+// Fuel consumed by post + pre to reset
+membrane_potential restored by NaK_ATPase(lactate_output)
+RRP_pool refilled by VATPase_pump(lactate_output)
+
+## intermediate time scale — temporary tuning (s → min)
+
+function short_term_plasticity(input_freq):
+
+// Presynapse: facilitate or depress based on Ca²⁺ history
+if input_freq > 20Hz: // facilitation
+vesicle_release_prob *= 1.3 // residual Ca²⁺ primes launchpad
+mobilize(reserve_pool → RRP_pool) // break storage chains
+elif input_freq < 5Hz: // depression
+vesicle_release_prob *= 0.7 // RRP depleted faster than refill
+
+// Postsynapse: NMDA gate primed if frequency sustained
+if input_freq >= 50Hz and duration > 1s:
+NMDA_Mg_block = False // sustained depolarization
+postsynaptic_Ca accumulates // early-LTP signal rises
+
+// Astrocyte: sense volume → deploy co-agonist
+if glutamate_cleft > threshold_mid:
+D_serine_release += gliotransmitter_pulse() // acoustic stabilizer
+astro_Ca += IP3_wave()
+
+// Neuromodulators: shift operational threshold globally
+LTP_threshold *= gain(1 / (1 + acetylcholine_level))
+signal_to_noise += norepinephrine_level × β_receptor_gain
+
+## slow time scale — structural carving (h → weeks)
+
+function late_LTP_consolidation():
+
+// Gate: dopamine "save button" must arrive
+if postsynaptic_Ca > Ca_LTP_threshold and dopamine_level > D1_threshold:
+
+// Postsynapse: anchor new receptors
+AMPA_count += receptor_insertion(CaMKII_signal)
+spine_volume *= 1.5 // spine head enlarges
+
+// Presynapse: expand active zone, fill launchpad
+active_zone_size *= 1.4
+vesicle_release_prob += 0.1 // VGCC clustering beneath AZ
+
+// Astrocyte: seal the acoustic channel
+ECM_integrity += secrete(Glypicans, Thrombospondins)
+retract(perisynaptic_process) // astrocyte walls in closer → insulate
+glutamate_clearance_rate *= 0.85 // tighter diffusion barrier
+
+// Late-LTP endpoint: carved channel
+return synapse_state = "potentiated"
+
+
+function LTD_active_forgetting():
+
+// Trigger: low-freq, out-of-sync — discordant leakage only
+if input_freq ≈ 1Hz and timing == "uncorrelated":
+// Postsynapse: small Ca²⁺ rise activates phosphatases
+AMPA_count -= receptor_internalization(PP1_signal)
+
+// Astrocyte: deploy molecular scissors → dissolve matrix
+D_serine_release = 0 // cut co-agonist supply
+ECM_integrity -= secrete(MMPs) // matrix metalloproteinases
+
+// Presynapse: dismantle launchpad
+active_zone_size -= docking_slot_removal()
+vesicle_release_prob *= 0.6
+sequester(RRP_pool → reserve_pool)
+
+return synapse_state = "depressed"
+
+
+function shockwave_lockdown(): // Mode 3 — >100Hz uncoordinated
+
+// Astrocyte: global Ca²⁺ wave triggers circuit-breaker
+astro_Ca = GLOBAL_WAVE // soma-level flood
+release(GABA, ATP) // gel floods postsynapse
+AMPA_count -= mass_internalization()
+membrane_potential = HYPERPOLARIZED
+
+// Presynapse: overdrive clustering to preserve signal
+cluster(VGCC → beneath_active_zone) // ensures penetration
+
+## energy supply chain — metabolic gating (continuous)
+
+function metabolic_loop(Δt):
+// Astrocyte: glucose → lactate pipeline
+glucose_uptake = blood_capillary_supply()
+lactate_output = glycolysis(glucose_uptake, glutamate_clearance_rate)
+
+// Both neurons absorb lactate → power pumps
+RRP_pool refill rate ∝ VATPase(lactate_output)
+membrane_potential reset ∝ NaK_ATPase(lactate_output)
+
+// Feedback: harder clearance work → faster fuel pump
+lactate_output *= load_factor(glutamate_clearance_rate)
+
+
+**State variables** at the top declare every quantity that gets modified — split by which cell "owns" it. These are the nodes that the rest of the code reads and writes.
+
+**Three time-scale functions** then show how those variables evolve:
+- `fire_action_potential` is pure fast physics — Ca²⁺ triggers vesicle release, AMPA opens, NMDA unlocks only under coincidence, astrocyte clears the cleft, fuel is consumed.
+- `short_term_plasticity` runs on top of repeated firing — the presynapse facilitates or depresses based on Ca²⁺ history, the astrocyte drops D-serine when volume is high, and neuromodulators shift the gain coefficient globally.
+- `late_LTP_consolidation` and `LTD_active_forgetting` are the permanent rewrite layer — they require the dopamine "save button" as an AND-gate, and they modify structural variables (`active_zone_size`, `ECM_integrity`, `AMPA_count`) that persist independently of individual spikes.
+
+The `shockwave_lockdown` and `metabolic_loop` sit alongside as two special-case routines that override the normal flow — one a circuit-breaker, the other a continuous background process coupling astrocyte workload to fuel delivery.
+
+---
+---
+
 # Core business of each component
 
 ## 1. The Core Businesses of Each Component