## 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).