organism/neuron/appunti/2026-03-30-behavior-POST.md

BEH-POST-UNIFIED: The Integrated Postsynaptic Model

ms: behaviors (Fast Kinetics & Gate Logic)

Voltage-Context: Episode

Determines the total depolarization level (Vpost​) available to clear the NMDA Mg-block.

• Vpost_Maximum: Episode
  • — V_bAP full OR (g_AMPA full AND V_bAP medium)
  • — Result: Vpost​ is high enough for complete Mg-block removal.
• Vpost_Attenuated: Episode
  • — g_AMPA medium AND V_bAP empty/low
  • — Result: Vpost​ is sub-threshold; Mg-block partially remains.
• Vpost_Passive: Episode
  • — g_AMPA empty AND V_bAP empty
  • — Result: Vpost​ at rest; Mg-block fully intact.

NMDA-Coincidence: Context

• NMDA_Open: Episode
  • — NT_cleft full AND V_post maximum
  • — Result: Capost​ surges; triggers high ATP demand for clearance.
• NMDA_LogicBlocked: Episode
  • — NT_cleft full BUT V_post attenuated/passive
  • — Result: Mg-block prevents Ca2+ influx despite NT presence.
• NMDA_LigandBlocked: Episode
  • — V_post maximum BUT NT_cleft empty
  • — Result: No glutamate to open the channel; Ca2+ entry zero.

Ca-Dynamics & ATP-Drain: Context

• Clearance_Optimal: Episode
  • — ATP_level_post full
  • — Result: Pumps flush Ca2+ rapidly; ATP_demand_post increases.
• Clearance_Failing: Episode
  • — ATP_level_post low/empty
  • — Result: Ca2+ remains elevated (residual floor); creates "False Trigger" conditions.

---

sec: behaviors (Signal Integration & Fate)

Synaptic-Weight-Decision (Plasticity)

• Plasticity_LTP: Episode
  • — Ca_post_history (recent 2s) is Full
  • — Result: High-frequency/High-amplitude coincidence detected; tags synapse for AMPA increase.
• Plasticity_LTD: Episode
  • — Ca_post_history is Medium
  • — Result: Low-frequency or poorly timed coincidence; tags synapse for AMPA removal.

Retrograde-Feedback (eCB)

• eCB_Synthesis_Active: Episode
  • — Ca_post_history > threshold (0.7)
  • — Logic A (Protection): Response to genuine NMDA over-activity.
  • — Logic B (Error): Response to pump failure (Ca2+ accumulation due to low ATP).
• eCB_Synthesis_Idle: Episode
  • — Ca_post_history < threshold; eCB level decays.

---

min: behaviors (Bioenergetics & Structural Change)

Metabolic-Recovery

• Astrocyte_Supply_Active: Episode
  • — Glucose_level full; ATP_level_post is replenished.
• Astrocyte_Supply_Crises: Episode
  • — Glucose_level low; ATP_level_post remains empty; Ca2+ pumps fail.

Structural-Update

• AMPA_Population_Increase: Episode
  • — Triggered by Plasticity_LTP AND ATP_level_post NOT empty.
  • — Result: g_AMPA_baseline shifts higher for next cycle.
• AMPA_Population_Decrease: Episode
  • — Triggered by Plasticity_LTD.
  • — Result: g_AMPA_baseline shifts lower.

---

Key Structural Observations

1. The Vpost Priority: Vpost​ is now the "sum" of local input and global feedback. This allows the model to simulate both Hebbian learning (needs a bAP) and Homeostatic Scaling (where enough local AMPA activity can eventually trigger the NMDA gate alone).
2. The ATP Bottleneck for LTP: Note that in the min behaviors, I’ve added a constraint: LTP requires ATP_level_post to be healthy. Moving receptors into the membrane is a physical "work" process. If the synapse is energy-starved, it might "decide" to do LTP in the sec loop but fail to execute it in the min loop.
3. The Coincidence Hierarchy:
   • LTP = Perfect Timing (NT + bAP).
   • LTD = Misaligned Timing (Low NT or Out-of-sync bAP).
   • False eCB = Metabolic Failure (No NT, No bAP, just Low ATP).