diff --git a/elements/neuron/appunti/2026-06-18-tripartite_synapse_v9.md b/elements/neuron/appunti/2026-06-18-tripartite_synapse_v9.md new file mode 100644 index 0000000..5b052ae --- /dev/null +++ b/elements/neuron/appunti/2026-06-18-tripartite_synapse_v9.md @@ -0,0 +1,767 @@ +# Commenti + +Endurance need is deposited only on interrupted success, not on bare depletion. Each component's DAY block now has a two-condition test: budget gated a behavior AND that behavior was on a successful trajectory (the local definition you specified — rising postsynaptic engagement for pre, climbing calcium for post, active distal spines for dend, and so on). Depletion during useless activity deposits nothing. + +Endurance bypasses dopamine. The endurance_need trace gates the NIGHT budget-ceiling adaptation directly, with no neuromodulatory coincidence. This is the homeostatic-versus-associative distinction: strength requires significance, endurance only requires that fuel was the binding constraint on a forming success. +Budget capacity is now fully parallel to structure. Fast budget (occupancy, filled in DAY) versus slow budget_ceiling (capacity, built in NIGHT) mirrors exactly the occupancy-versus-structure distinction. The budget is clamped by its ceiling during DAY. + +The two drives compete for one pool. Step 2b draws from the same material and energy as the structural commits in step 2, so building endurance somewhere prevents building strength elsewhere. A connection that is both significant and fuel-limited is the strongest competitor, drawing on both — which can force depotentiation of others. + +Decay is by neglect, consistently. Budget ceilings decay when endurance need is not renewed (mitophagy removing idle mitochondria), exactly as structures decay when not maintained. + +One thing worth your scrutiny: I kept the endurance need decaying over minutes (intermediate timescale) and cleared at NIGHT, while the budget_ceiling persists like structure. Check whether that split feels right, or whether endurance need should itself persist partially across nights for multi-night metabolic conditioning, the way tags can carry forward. + +# Tripartite Synapse — Pseudocode v9 +New in v9: BUDGET CAPACITY as an adaptive quantity (endurance), parallel to STRUCTURE (strength) + - budget_ceiling: slow capacity on the fast budget (like structure is on occupancy) + - endurance_need trace: deposited when depletion INTERRUPTS A SUCCESSFUL TRAJECTORY + (not mere depletion — depletion that cut short something on its way to success) + - NIGHT builds budget_ceiling where fuel was the binding constraint on a valuable outcome + - structure (strength) ← validated coincidence ; budget_ceiling (endurance) ← interrupted success + +--- + +## Two NIGHT-built capacities, two different drives + +``` +STRENGTH = structure ceiling + driven by: coincidence (2 or 3, per component) + dopamine validation + answers: "did a valuable coincidence COMPLETE and get validated?" + builds: bigger containers (more slots) → stronger per-event behavior + +ENDURANCE = budget ceiling + driven by: depletion that INTERRUPTED a successful trajectory + answers: "did fuel run out exactly when a valuable outcome was forming?" + builds: bigger fuel capacity → longer-sustainable behavior + NO dopamine required — this is metabolic/homeostatic, not associative + +Diagnostic combinations: + high structure tag, low endurance need → significant + sustainable → strengthen + low structure tag, high endurance need → fuel-limited at verge → fund endurance + high both → significant + fuel-limited → strengthen + fund + low both → idle, or failing for non-fuel reasons → let decay +``` + +--- + +## Part 1 — Conventions (additions to v8) + +``` +NEW VARIABLE TYPES: + ENDURANCE_TRACE = deposited when budget depletion interrupts a SUCCESSFUL trajectory + decays over minutes + NO dopamine gate (metabolic, not associative) + gates NIGHT budget_ceiling adaptation + BUDGET_CEILING = slow capacity on the fast budget + READ in DAY (clamps how high budget can be / how long behavior sustains) + WRITTEN in NIGHT (raised by endurance need, decays when unused) + +KEY DISTINCTION: + budget = fast occupancy (current fuel level) — consumed/refilled in DAY + budget_ceiling = slow capacity (max fuel / endurance) — adapted in NIGHT + (exactly parallel to: occupancy filled in DAY vs structure ceiling built in NIGHT) +``` + +--- + +## Part 2 — New Trace and Capacity Variables (per component) + +``` +// Endurance traces — deposited only on INTERRUPTED SUCCESS +ENDURANCE_TRACE pre_endurance_need +ENDURANCE_TRACE post_endurance_need +ENDURANCE_TRACE dend_endurance_need +ENDURANCE_TRACE soma_endurance_need +ENDURANCE_TRACE axon_endurance_need +ENDURANCE_TRACE astro_endurance_need + +// Budget ceilings — slow endurance capacity, WRITTEN in NIGHT +BUDGET_CEILING pre_budget_ceiling +BUDGET_CEILING post_budget_ceiling +BUDGET_CEILING dend_budget_ceiling +BUDGET_CEILING soma_budget_ceiling +BUDGET_CEILING axon_budget_ceiling +BUDGET_CEILING astro_budget_ceiling + +// Each DAY budget is now clamped by its ceiling: +// {c}_budget = clamp({c}_budget, 0, {c}_budget_ceiling) + +// New fixed params +FIXED endurance_threshold // min endurance_need to trigger ceiling growth +FIXED capacity_decay_rate // budget_ceiling decay when unused +FIXED trajectory_threshold // min "success trajectory" to count an interruption as costly +``` + +--- + +## Part 3 — How Each Component Detects "Interrupted Success" + +``` +// The endurance signal requires TWO things at the moment of depletion: +// 1. budget gated a behavior (depletion occurred) +// 2. that behavior was on a SUCCESSFUL TRAJECTORY (local definition per component) +// Only their conjunction deposits endurance_need. + +PRE success trajectory = postsynaptic engagement was RISING + (release was building a coincidence) +POST success trajectory = post_fast_trace was APPROACHING Ca_TAG_threshold + (calcium was building toward a tag) +DEND success trajectory = active spines existed DISTAL to the propagation failure point + (bAP was needed downstream and got cut off) +SOMA success trajectory = nuclear Ca was APPROACHING CREB threshold, or + firing was successfully recruiting downstream +AXON success trajectory = propagation failed to ENGAGED boutons (driving active synapses) +ASTRO success trajectory = postsynapse was DEPOLARIZED and WAITING for D-serine + (gate needed exactly when synthesis ran out) +``` + +--- +--- +# SCOPE: DAY + Additions shown per component. Existing v8 behavior assumed unless noted. + Budget is now clamped by budget_ceiling. Endurance need deposited on interrupted success. + +--- + +## PRE | CONTEXT: AP (additions) +``` +scope DAY | context AP: + + // Budget now clamped by its ceiling + pre_budget = clamp(pre_budget, 0, pre_budget_ceiling) + + // Depletion gate — now also tests success trajectory + if pre_budget < AP_release_cost: + suppress(NT_flux) + // INTERRUPTED SUCCESS? was release building a coincidence downstream? + if postsynaptic_engagement_rising: // e.g. post_fast_trace was climbing + pre_endurance_need += postsynaptic_engagement // graded by how close to success + // fuel was the binding constraint on a forming coincidence + // else: depletion during ineffective firing → NO endurance need (let it fail) + exit context + + // ... rest of v8 PRE AP behavior unchanged ... + pre_fast_trace += spike_Ca_influx(input_freq); pre_fast_trace *= decay(τ=100ms) + Ca_drive = pre_fast_trace / (K_Ca_release + pre_fast_trace) + if RRP_level > 0: + NT_flux = RRP_level × Ca_drive + glutamate += NT_flux × Δt; RRP_level -= NT_flux × Δt + pre_budget -= NT_flux × fusion_cost + // ... refill, brake ... +``` + +## PRE | CONTEXT: NOT_AP (additions) +``` +scope DAY | context NOT_AP: + + // endurance trace decays like other intermediate traces + pre_endurance_need *= decay(τ=minutes) + + // ... rest of v8 PRE NOT_AP unchanged: budget replenish, refill, tagging ... + pre_budget += astro_lactate[syn] × pre_fraction + axon_shipment_to_pre + pre_budget = clamp(pre_budget, 0, pre_budget_ceiling) + // ... possible_tagging, tag ... +``` + +--- + +## POST | CONTEXT: NOT_bAP (additions) +``` +scope DAY | context NOT_bAP: + + post_budget = clamp(post_budget, 0, post_budget_ceiling) + + // Depletion during receptor trafficking or membrane reset + if post_budget < required_cost: + // INTERRUPTED SUCCESS? was calcium climbing toward a tag? + if post_fast_trace > trajectory_threshold and post_fast_trace_rising: + post_endurance_need += post_fast_trace // collapse of a building tag-trajectory + // fuel (trafficking/reset) was the limit on completing a coincidence + // truncate the behavior + // else: depletion during low-calcium activity → no endurance need + + post_endurance_need *= decay(τ=minutes) + // ... rest of v8 POST NOT_bAP: AMPA, NMDA, STP slot-fill, tagging ... +``` + +--- + +## DEND | CONTEXT: bAP (additions) +``` +scope DAY | context bAP: + + dend_budget = clamp(dend_budget, 0, dend_budget_ceiling) + + // bAP propagation may fail partway if budget insufficient + bAP_local, propagation_reached = propagate_bAP(SOMA.AP_fired, dend_structure, dend_budget) + dend_budget -= bAP_propagation_cost × propagation_reached + + // INTERRUPTED SUCCESS? were there active spines BEYOND where propagation died? + if propagation_failed_early and active_spines_distal_to(propagation_reached) > 0: + dend_endurance_need += active_spines_distal_to(propagation_reached) + // distal active spines were cut off from the retrograde signal by lack of fuel + // else: propagation failure with no distal active spines → no endurance need + + // ... rest of v8 DEND bAP: branch Ca trace, integration ... +``` + +## DEND | CONTEXT: NOT_bAP (additions) +``` +scope DAY | context NOT_bAP: + dend_endurance_need *= decay(τ=minutes) + // ... v8 replenish, ship to post, tagging, local translation ... +``` + +--- + +## SOMA | CONTEXT: AP (additions) +``` +scope DAY | context AP: + + soma_budget = clamp(soma_budget, 0, soma_budget_ceiling) + + // If budget can't sustain firing during a recruiting train + if soma_budget < AP_generation_cost: + // INTERRUPTED SUCCESS? was nuclear Ca climbing toward CREB, + // or was firing recruiting downstream activity? + if soma_fast_trace > trajectory_threshold and soma_fast_trace_rising: + soma_endurance_need += soma_fast_trace + // fuel cut a firing pattern that was achieving integration/CREB approach + // suppress firing this step + else: + // ... normal v8 SOMA AP: fire, deposit 3 traces, tagging ... + + soma_endurance_need *= decay(τ=minutes) +``` + +--- + +## AXON | CONTEXT: AP (additions) +``` +scope DAY | context AP: + + axon_budget = clamp(axon_budget, 0, axon_budget_ceiling) + + propagation_reliability = axon_structure.propagation × (1 - failure_rate(axon_fast_trace)) + // budget can further reduce reliability if depleted + if axon_budget < AP_propagation_cost: + propagation_reliability *= budget_limited_factor + // INTERRUPTED SUCCESS? did failure hit ENGAGED boutons (driving active synapses)? + if failed_boutons_engaged > 0: + axon_endurance_need += failed_boutons_engaged + // fuel cut propagation to terminals that were successfully driving synapses + // else: failure to idle boutons → no endurance need + + axon_endurance_need *= decay(τ=minutes) + // ... rest of v8 AXON AP ... +``` + +--- + +## ASTRO | CONTEXT: CONTINUOUS (additions) +``` +scope DAY | context CONTINUOUS: + + astro_central_budget = clamp(astro_central_budget, 0, astro_budget_ceiling) + + // D-serine release is budget-limited (v8). Now detect interrupted success: + if glutamate[i] > spillover_threshold: + Ds_drive = astro_fast_trace[i] / (K_Ca_Dserine + astro_fast_trace[i]) + Ds_wanted = Ds_drive × Ds_max + Ds_supplied = min(Ds_wanted, astro_central_budget × Ds_fraction) + + if Ds_supplied < Ds_wanted: + // INTERRUPTED SUCCESS? was postsynapse DEPOLARIZED and waiting for the gate? + if post_depolarized[i] and post_fast_trace[i] approaching Ca_TAG_threshold: + astro_endurance_need[i] += (Ds_wanted - Ds_supplied) + // ran out of synthesis capacity exactly when the gate was needed + // else: insufficient D-serine but no waiting coincidence → no endurance need + + astro_D_serine[i] += Ds_supplied + // ... rest of v8 astro overflow handling, tagging ... + + astro_endurance_need[i] *= decay(τ=minutes) +``` + +--- +--- +# SCOPE: NIGHT + v8 steps unchanged EXCEPT: add Step 2b (budget capacity adaptation). + Budget capacity competes for the SAME material + energy as structure. + +--- + +## Step 1 — Replenish & Distribute (unchanged from v8) +``` +// energy economy: astrocyte → astrosynapses +// material economy: soma → branches/axon → spines/boutons +// next-DAY budgets pre-loaded +``` + +## Step 2 — Structural Commits (strength) (unchanged from v8) +``` +// each commit raises a STRUCTURE ceiling, gated by tag + material + energy +// driven by COMPLETED VALIDATED COINCIDENCE +``` + +## Step 2b — Budget Capacity Adaptation (endurance) ★ NEW +``` +scope NIGHT | step 2b: + + // Driven by endurance_need (interrupted success), NOT by tags, NOT by dopamine. + // Competes for the SAME material + energy pools as structural commits (step 2). + // → endurance and strength trade off under scarcity. + + for each component c: + + if c_endurance_need > endurance_threshold: + // fuel was the binding constraint on a valuable outcome → build endurance + Δcap = min(capacity_expansion_cost, + c_material × cap_material_fraction, // mitochondria need proteins + c_energy × cap_energy_fraction) // biogenesis needs ATP + c_budget_ceiling += Δcap + c_material -= Δcap + c_energy -= Δcap × biogenesis_cost + if Δcap < capacity_expansion_cost: + queue(c_endurance_deficit → next NIGHT) + // biological basis: activity-driven mitochondrial biogenesis, + // local fuel-storage expansion + + else: + // endurance exceeded demand (or failures weren't costly) → let ceiling decay + c_budget_ceiling -= capacity_decay_rate × Δt_night + c_material += released_mitochondria(c) × recycling_fraction + // biological basis: mitophagy — unused metabolic capacity removed, + // proteins returned to pool for components that need them + + // NOTE on competition with strength (step 2): + // material/energy spent here cannot fund structural growth there. + // a component that is significant (high tag) AND fuel-limited (high endurance_need) + // demands both → highest total resource draw → strongest competitor for the pool + // → may force heterosynaptic depression / depotentiation elsewhere +``` + +## Step 3 — Passive Depotentiation (extended) +``` +scope NIGHT | step 3: + + // structures decay unless maintained (v8) ... + // ALSO: budget_ceilings decay if not reinforced by endurance_need (handled in 2b else-branch) + + // maintenance now must cover BOTH structure and budget_ceiling: + // a component maintains its endurance only while it keeps earning endurance_need + // unused endurance capacity is the first thing sacrificed under scarcity + // (mitochondria are expensive to keep — mitophagy removes idle ones) +``` + +## Step 4 — Homeostatic Scaling (unchanged from v8) +## Step 5 — Clear Traces (extended) +``` +scope NIGHT | step 5: + // v8 clears: fast_traces, possible_tagging, soma timing traces, tags + // ALSO clear endurance traces (they have served their purpose this cycle): + all endurance_need = 0 + // budget_ceilings PERSIST (they are slow capacity, like structure) +``` + +--- + +## Summary — Two Capacities, Two Drives, One Resource Pool + +``` + STRENGTH (structure) ENDURANCE (budget_ceiling) +DAY signal coincidence completed + depletion INTERRUPTED a + validated (tag set) successful trajectory (endurance_need) +gate dopamine required NO dopamine (homeostatic) +NIGHT builds bigger slots (per-event power) bigger fuel cap (sustain duration) +competes for shared material + energy SAME shared material + energy +decays when unmaintained (neglect) unused / failures not costly (mitophagy) + +JOINT LOGIC: + to be remembered AND sustainable, a connection must + - complete validated coincidences (→ strength), AND + - either not be fuel-limited, or earn endurance by failing-at-the-verge (→ endurance) + under scarcity the two drives compete: + building endurance somewhere spends material that can't strengthen elsewhere + the system invests endurance specifically where FUEL, + not structure or significance, was what stood between activity and success. +``` + +# Flows + +Per ora abbiamo in DAY il {component}_budget che raggruppa energy e material, e in NIGHT {component}_energy e {component}_material. + +This maps onto a real biological distinction. The astrocyte's lactate and the soma's ATP fund the running costs of the cell — everything that needs to happen just to keep the system operating from moment to moment. CREB-driven protein synthesis funds the capital investment — the slow, expensive structural changes that modify what the running system is capable of. These are two different budgets in the biological sense: operating expenditure versus capital expenditure. Combining them within DAY is correct because DAY is entirely operating expenditure. Keeping them separate in NIGHT is correct because NIGHT mixes operating expenditure with capital expenditure, and only the capital component is recoverable. + +Combining {component}_energy e {component}_material would hide the fact that dismantling a structure recovers biological building blocks but not the work that was done to assemble them — which is the thermodynamic reality of any construction and deconstruction process. + + +## Energy flow + +``` +VASCULAR SUPPLY + → ASTROCYTE CELL BODY + glucose → lactate (glycolysis) + → astro_budget (local ATP for clearance, D-serine, ECM, process motility) + → lactate exported to: + → pre_budget (ATP for VGCC, vesicle fusion, VATPase) + → post_budget (ATP for NaK pump, AMPA trafficking, actin) + → dend_budget (ATP for bAP propagation, local translation) + + → SOMA + soma has own mitochondria — partly self-fueled + soma_budget (ATP for AP generation, CREB, protein synthesis, shipping) + → dend_budget top-up (organelle delivery) + → axon_budget top-up (transport machinery) +``` + +## Material flow + +``` +SOMA + protein synthesis (CREB-driven, peaks in NIGHT) + → soma_material (receptors, scaffold proteins, organelles, mRNA) + → dend_material (branch receives proteins + mRNA from soma) + → post_material (spine receives receptors + actin from branch) + → axon_material (boutons receive AZ proteins + VGCCs from soma via axon) + → pre_material (bouton active zone proteins) + +ASTROSYNAPSE + ECM proteins synthesized in astrocyte cell body + → astro_material (Glypicans, Thrombospondins, serine for D-serine) + → cleft environment (ECM sealing, D-serine availability) +``` + +Yes, exactly. This is the essential abstract pattern. Let me state it precisely. + +# The Abstract Pattern + +A component operates within a structure set by the previous NIGHT. During DAY, in each context, it executes behaviors that cost budget and deposit fast traces. Fast traces are local records of recent activity that bias the next behavior and open an eligibility window for tagging. A tag forms when a local eligibility signal coincides with one or more non-local validation signals within the decay window of the trace — the number of required coincidences reflecting the spatial scale at which that component sits in the system. In contexts without triggering input, all traces decay, closing the windows they opened. At NIGHT, the tag magnitude drives a structural commit proportional to available material and energy — material being recoverable and energy not — with the structural change becoming the new ceiling within which the next DAY's behaviors will operate. What is not committed decays for lack of maintenance, and the resources freed by that decay partially fund the potentiation of what was. + +## DAY — The General Form + +Every DAY behavior follows this template: + +``` +given: STRUCTURE // the architectural ceiling left by NIGHT +in: CONTEXT // local or global triggering condition +if: BUDGET > cost // operational resources available +then: behavior executes + BUDGET -= cost // resources consumed + FAST_TRACE += f(behavior) // local record deposited +``` + +The fast trace then drives two parallel processes: + +**Within the same context** — the trace biases the next execution of the same behavior. This is the short-term modulation loop. It is entirely local and requires no external signal. + +**Across contexts** — the trace accumulates into `possible_tagging` when it exceeds the eligibility threshold. This is the bridge toward long-term change. It requires the trace to be sustained enough to survive into the NOT_AP or CONTINUOUS context. + +### The Tag Formation — Where Non-Locality Enters + +The abstract pattern for tag formation generalizes across all components but with different **coincidence requirements**: + +**PRE, DEND, SOMA, AXON, ASTRO — one non-local coincidence:** +``` +if FAST_TRACE > eligibility // local: this bouton was recently active + AND dopamine > threshold // non-local: organism-level reward signal +then: TAG += dopamine × possible_tagging +``` +One spatial scale beyond the local component is required. The organism must confirm that the recent activity was worth saving. + +**POST — two non-local coincidences:** +``` +// First coincidence (NOT_bAP context): +if FAST_TRACE > Ca_TAG_threshold // local: spine Ca²⁺ was high + AND D-serine > threshold // non-local 1: astrosynapse co-agonist +then: post_possible_tagging += FAST_TRACE // CANDIDATE + +// Second coincidence (bAP context): +if post_possible_tagging > threshold // local: CANDIDATE still present + AND bAP arrives // non-local 2: soma fired +then: FAST_TRACE amplified above Ca_HIGH + +// Tag stabilization (any context): +if post_possible_tagging > threshold // local: confirmed coincidence + AND dopamine > threshold // non-local 3: organism validation +then: TAG += dopamine × post_possible_tagging // STABLE +``` +Three spatial scales must align: astrosynapse, soma, organism. The postsynapse is the most constrained component — it requires the most non-local validation before committing. + +### Trace Recession — The Temporal Behavior + +In every NOT_AP or CONTINUOUS context, all traces decay: + +``` +FAST_TRACE *= decay(τ_fast) // ms to seconds — closes eligibility window +possible_tagging *= decay(τ_mid) // seconds to minutes — closes tagging window +TAG *= decay(τ_slow) // hours — closes commitment window +``` + +The decay is not a separate behavior — it is the passive consequence of molecular processes. But its effect is behavioral: it enforces that coincidences must happen within specific time windows. The system does not check timing explicitly — timing is enforced by the competition between accumulation and decay. + +## NIGHT — The General Form + +``` +given: TAG // strength of DAY evidence for this component + STRUCTURE // current architectural state +if: TAG > threshold // evidence strong enough to justify investment +then: + Δstructure = min(expansion_cost, + MATERIAL, // slow structural resources available + ENERGY × fraction) // assembly ATP available + STRUCTURE += Δstructure × coherence_bonus + MATERIAL -= Δstructure // RECOVERABLE after LTD + ENERGY -= Δstructure × ATP_cost // NOT recoverable +``` + +The coherence bonus appears when pre, post, and astro tags are all SET simultaneously — the three components of the synapse have all independently gathered evidence for the same structural change, which amplifies the commit beyond what any single tag would produce alone. + +What is not potentiated passively decays: + +``` +STRUCTURE -= decay_rate × Δt_night +STRUCTURE += min(maintenance_allocation, maintenance_cost) +// if maintenance_allocation < decay_rate × Δt_night: +// structure drifts down — depotentiation by neglect +``` + +# More details + +## SOMA + +### The Abstract Pattern Applied to Soma Timing + +The abstract pattern says: a behavior deposits a trace, the trace decays, and the trace biases the next behavior. For the soma, the AP is the behavior, and **the refractory period and threshold elevation should both be consequences of a single trace deposited by the AP, decaying back toward baseline**. Neither should be a hardcoded duration — both should emerge from the return of the trace to resting conditions. + +--- + +Yes, this is much more consistent with the rest of the architecture. The soma should not compute an explicit rhythm estimate and predict the next input — that is top-down. Instead, the **mismatch itself leaves a trace**, and that trace adjusts the refractory dynamics. Let me think through this carefully. + +--- + +### The Bottom-Up Mechanism + +The key event is: **a dendritic input arrives strong enough to fire the soma, but the soma is still refractory.** This is a missed opportunity — the input wanted to fire the cell, but the cell was not ready. This mismatch is the signal. + +Each time this happens, it should leave a trace that biases the refractory dynamics toward recovering faster in that timing window — so that next time an input arrives at that phase, the soma is ready. This is potentiation of the refractory recovery, occurring within DAY, driven entirely by the local coincidence of "input wanted to fire" and "soma was not ready." + +``` +scope DAY | context NOT_AP (within refractory): + + // Detect the mismatch: suprathreshold input during refractory + if branch_Vm > effective_threshold and soma_Na_inactivation > inactivation_threshold: + // Input arrived but soma could not fire — missed coincidence + refractory_alignment_trace += (branch_Vm - effective_threshold) + × soma_Na_inactivation + // graded: stronger input + deeper refractory → larger trace + // this is the "potentiation" signal for faster recovery +``` + +The `refractory_alignment_trace` then biases the recovery rate of the inactivation trace: + +``` + // Recovery rate biased by accumulated alignment trace + recovery_rate = base_recovery_rate × (1 + refractory_alignment_trace) + soma_Na_inactivation *= decay(τ_Na / recovery_rate) + // more alignment trace → faster recovery → soma ready sooner next time +``` + +--- + +### Why This Is Bottom-Up + +There is no rhythm estimation, no prediction of the next input time, no computed inter-input interval. The soma does not model its input. It simply notices, locally and reactively, that an input arrived when it was not ready, and leaves a trace that makes it recover faster. Over many such mismatches at the same phase, the recovery speeds up at that phase specifically — and the soma ends up aligned with its input rhythm **without ever representing that rhythm**. + +The alignment is an emergent statistical consequence of many local mismatch events, exactly as a potentiated synapse becomes tuned to its input without representing what it is tuned to. The phase-coupling appears, but nothing in the soma computed it. + +--- + +### Depotentiation as Neglect — Not Explicit + +Now the crucial part you raised: the depotentiation of refractory alignment must occur as a **consequence of not potentiating**, not as an explicit opposing mechanism. + +The `refractory_alignment_trace` decays continuously. If mismatches keep happening at a particular phase, the trace is continuously replenished and the fast recovery is maintained. If mismatches stop happening — because the input rhythm changed, or because the alignment succeeded and inputs now arrive when the soma is ready — then the trace is no longer replenished and **decays back toward baseline on its own**. + +``` + // No explicit depotentiation — just decay when not reinforced + refractory_alignment_trace *= decay(τ_alignment) + // if mismatches continue → trace replenished → fast recovery maintained + // if mismatches stop → trace decays → recovery returns to baseline +``` + +This is exactly parallel to synaptic depotentiation by neglect. The soma does not actively slow its recovery when alignment is no longer needed. It simply stops receiving the mismatch signal that was keeping the recovery fast, and the recovery drifts back to baseline because the trace that accelerated it is no longer reinforced. + +There is an elegant self-limiting property here. Once the soma is well-aligned, inputs arrive when it is ready, so there are no more mismatches, so the alignment trace stops being replenished and begins to decay. This would slowly de-align the soma — until inputs start arriving during refractory again, regenerating the mismatch and re-potentiating the alignment. The system settles into a dynamic equilibrium where just enough mismatch occurs to maintain just enough alignment. The soma hovers at the edge of alignment, continuously corrected by the residual mismatches that its imperfect alignment produces. + +--- + +### The Full Bottom-Up Soma Timing + +``` +scope DAY | context AP: + + effective_threshold = soma_structure.baseline_threshold + × (1 + soma_adaptation) + × neuromod_factor(NE_level, ACh_level) + + can_fire = (soma_Na_inactivation < inactivation_threshold) + + if branch_Vm > effective_threshold and can_fire: + AP_fired = True + soma_budget -= AP_generation_cost + + // Deposit traces from the AP + soma_Na_inactivation += AP_amplitude // fast — refractory + soma_adaptation += AP_contribution // slow — spike train threshold + soma_fast_trace += nuclear_Ca_influx() // slow — plasticity tagging + +scope DAY | context NOT_AP: + + // MISMATCH DETECTION — bottom-up alignment signal + if branch_Vm > effective_threshold and soma_Na_inactivation > inactivation_threshold: + // input wanted to fire but soma was refractory — missed coincidence + refractory_alignment_trace += (branch_Vm - effective_threshold) + × soma_Na_inactivation + // local potentiation of recovery — no prediction, no rhythm model + + // Recovery biased by alignment trace + recovery_rate = base_recovery_rate × (1 + refractory_alignment_trace) + soma_Na_inactivation *= decay(τ_Na / recovery_rate) // faster if aligned + soma_adaptation *= decay(τ_adaptation) + soma_fast_trace *= decay(τ_nuclear) + + // Alignment trace decays — depotentiation by neglect, not explicit + refractory_alignment_trace *= decay(τ_alignment) + // maintained only while mismatches continue + // self-limiting: good alignment → fewer mismatches → trace decays → + // slight de-alignment → mismatches return → re-potentiation + + // ... budget replenishment, shipments, tagging as before ... +``` + +--- + +### The Conceptual Payoff + +This makes the soma's temporal alignment obey exactly the same principles as everything else in the system: + +A behavior leaves a trace — here the missed coincidence leaves the alignment trace. + +The trace biases future behavior — here it accelerates recovery so the next input at that phase succeeds. + +Potentiation is the active drive — the soma actively speeds up recovery in response to mismatch. + +Depotentiation is neglect — the alignment trace decays when mismatches stop, with no explicit opposing process. + +The system finds equilibrium through the residual of its own imperfection — just enough mismatch persists to maintain just enough alignment. + +And critically, the soma achieves temporal prediction — firing in phase with its input rhythm — **without ever representing the rhythm**. The prediction is implicit in the structure of the recovery dynamics, built up from purely local, reactive, bottom-up trace deposits. This is the same way a potentiated synapse "predicts" that its input will be significant without representing the prediction: the prediction is the physical bias left by past experience, not a computed expectation. The soma's phase-coupling is the temporal version of the synapse's weight — both are implicit predictions encoded as physical bias, both built bottom-up from local coincidence, both maintained by reinforcement and lost by neglect. + +## Energy depletion in Presynapse + +how does the budget and energy influence the model. If for example a presynapse has no more energy variuos times during day, what happens? + +Good question. Let me trace through exactly what happens when energy is repeatedly depleted, following the mechanics already in the pseudocode. + +--- + +### The Immediate Effect — Behavior Suppression + +When `pre_budget < AP_release_cost`, the pseudocode does: + +``` +if pre_budget < AP_release_cost: + suppress(NT_flux) + exit context +``` + +So the immediate consequence of an energy-depleted bouton is **silence** — it does not release neurotransmitter for that AP, regardless of how strong the incoming spike was. The AP arrives, but nothing comes out the other side. This is biologically real: ATP-depleted boutons fail to release because the VATPase cannot refill vesicles and the calcium pumps cannot maintain the gradients that drive release. + +--- + +### The Cascade of Consequences Within DAY + +A single depletion is recoverable — the bouton refuels from astrocyte lactate in the next NOT_AP context and resumes. But **repeated depletion during DAY** sets off a cascade that runs through the entire trace and tagging machinery. + +**No release means no glutamate means no downstream trace.** When the bouton is silent, no glutamate reaches the cleft. The postsynapse receives no AMPA current, its NMDA channels do not open, and `post_fast_trace` does not rise. The astrosynapse detects no spillover, so `astro_fast_trace` does not rise and no D-serine pulse is released. The entire synaptic event simply does not happen. A bouton that is energy-depleted at the moment a significant pattern arrives causes that pattern to be invisible to the postsynapse — the synapse fails to participate in whatever the network is doing. + +**No participation means no eligibility.** Because the bouton did not release, `pre_fast_trace` is not elevated by a release event (it still rises from calcium influx, but without the reinforcing facilitation of successful release). More importantly, the postsynapse, having received no input, accumulates no `post_possible_tagging`. When dopamine arrives to validate the moment, there is nothing to validate at this synapse — the eligibility window is empty. The synapse misses the tagging opportunity entirely. + +**Missing the tag means missing the NIGHT commit.** Since no tag was set during DAY, the synapse has nothing to draw structural resources with during NIGHT. It does not potentiate. And because the system's depotentiation is by neglect, **a synapse that fails to potentiate is automatically on the path to depotentiation** — it receives only maintenance allocation, and if other synapses potentiated and drew down the shared pool, even maintenance may be insufficient. + +--- + +### The Deeper Consequence — Energy Depletion Becomes Structural Depression + +Here is the important emergent property: **repeated energy depletion at a bouton during DAY leads to its structural depression during NIGHT, even though no depression signal was ever sent.** + +The chain is entirely passive: + +``` +repeated pre_budget depletion in DAY + → bouton silent during significant events + → no glutamate release + → no post_fast_trace, no post_possible_tagging + → no tag set (pre or post) + → no NIGHT structural commit at this synapse + → only maintenance allocation received + → if pool depleted by other synapses' potentiation: + maintenance insufficient + → pre_structure and post_structure decay + → DEPOTENTIATION +``` + +The energy-starved synapse is outcompeted not because it was marked for depression but because it could not generate the activity needed to claim resources. Energy availability during DAY therefore directly determines which synapses can even enter the competition for NIGHT potentiation. + +--- + +### The Feedback Loop — Depression Reduces Future Energy Demand + +There is a stabilizing feedback here. A depotentiated synapse has smaller `pre_structure` — a smaller active zone, fewer docking slots, lower release probability. This means it costs **less energy to operate**. So a synapse that was energy-starved and consequently depotentiated now has lower energy demands, making it less likely to be energy-starved in the future. + +``` +energy depletion → depotentiation → smaller structure → lower energy demand + → less likely to deplete → stabilizes at a low-activity equilibrium +``` + +The synapse settles into a low-energy, low-structure, low-activity state. It is not dead — it still operates at baseline — but it has been demoted from the pool of synapses competing for potentiation. Energy scarcity has selected it out. + +--- + +### Why This Is Functionally Important + +This is not a bug — it is a resource-allocation mechanism with real computational value. + +**Energy availability acts as a second gate on plasticity, parallel to the neuromodulatory gate.** Dopamine asks "was this worth saving?" Energy asks "can this synapse afford to participate?" A synapse must pass both gates to be potentiated. This means the system preferentially potentiates synapses that are both behaviorally significant AND metabolically sustainable. A synapse that cannot sustain its own activity is not a good candidate for strengthening, because strengthening it would only increase its energy demand and make it fail more often. + +**Local energy competition implements a form of spatial sparsification.** Boutons on the same axon share `axon_budget` and ultimately the same astrocytic lactate supply. When many boutons are active simultaneously, the shared energy is divided among them, and the weakest — those with the least efficient structure or the least reliable input — deplete first and fall silent. This automatically sparsifies activity: under energy pressure, only the most robust synapses keep firing, and they are the ones that get potentiated. The system concentrates its limited resources on its strongest connections. + +**The astrocyte's energy delivery becomes a control signal.** Because the astrocyte controls lactate distribution across its territory, it has indirect control over which synapses can sustain activity and therefore which can be potentiated. A region of the astrocyte territory that is well-perfused and well-fueled supports vigorous plasticity. A region that is metabolically stressed — perhaps because of high overall demand or reduced vascular supply — suppresses plasticity in its synapses regardless of their activity. This couples the metabolic state of the tissue directly to its capacity to learn. + +--- + +### What Repeated Depletion Looks Like Over Days + +If a bouton is chronically energy-starved across multiple DAY cycles — perhaps because it is in a metabolically compromised region, or because it is competing with many highly active neighbors — the trajectory is: + +``` +Day 1: depletes occasionally → misses some events → weak tag → partial commit +Day 2: smaller structure → still depletes under load → weaker tag → less commit +Day 3: structure decaying → maintenance insufficient → depotentiation accelerates +... +Equilibrium: minimal structure, minimal energy demand, minimal participation + synapse survives but is functionally silent + resources it would have consumed now available to neighbors +``` + +This is a reasonable model of what happens to synapses in metabolically stressed tissue — they do not die immediately, but they are progressively silenced and depotentiated, freeing their resources for synapses in healthier regions. It is also a model of how chronic metabolic limitation — aging, vascular disease, mitochondrial dysfunction — would manifest as a gradual loss of plasticity capacity: not through any depression signal, but through the simple inability of energy-starved synapses to participate in the activity that would let them claim resources. + +The energy budget is therefore not just a constraint that occasionally blocks behavior — it is a continuous selective pressure that shapes which synapses thrive and which fade, operating silently in parallel with the explicit activity-and-reward-driven plasticity, and ultimately determining the metabolic sustainability of whatever the system chooses to remember. + +## Three parallel competitive resource economies +The neuronal structural economy — soma produces material, distributed through dendrite to spines and through axon to boutons, competed for by tagged synapses during NIGHT. +The astrocytic energy economy — astrocyte cell body produces lactate, distributed to perisynaptic processes, competed for by active synapses during DAY in proportion to their clearance demand. +The soma's own energy economy — soma mitochondria fuel AP generation and shipping, competed for by the soma's own functions. +All three share the same logic: a central producer with a capped output, distribution to peripheral consumers, demand-weighted allocation, and a self-reinforcing coupling where stronger consumers both demand and receive more. And all three ultimately bottom out at the same vascular glucose ceiling — the astrocyte directly, the soma through its own glucose uptake. +The deep consequence is that a synapse must win on both economies to be potentiated. It must generate enough activity to pull lactate from the astrocyte (energy economy) AND accumulate enough tag to draw material during NIGHT (structural economy). A synapse that wins the structural competition but cannot pull energy will be unable to sustain the activity that justified its potentiation — it will be a large, expensive structure that keeps going silent. A synapse that pulls energy but never accumulates a tag stays metabolically supported but structurally weak. Only synapses that win both — active enough to be fueled, significant enough to be tagged — achieve and maintain full potentiation. The two economies together implement a stringent joint criterion: persistent significant activity that the metabolic infrastructure can sustain. diff --git a/elements/neuron/appunti/old/2026-06-15-tripartite_synapse_v8.md b/elements/neuron/appunti/old/2026-06-15-tripartite_synapse_v8.md new file mode 100644 index 0000000..4e77ad9 --- /dev/null +++ b/elements/neuron/appunti/old/2026-06-15-tripartite_synapse_v8.md @@ -0,0 +1,1035 @@ +--- +include_toc: true +--- + +# Tripartite Synapse — Pseudocode v8 + +## Unifying principles + +``` +1. CAPACITY vs OCCUPANCY + NIGHT builds containers (raises structural ceilings). + DAY fills containers (occupancy driven by calcium / activity). + Short-term potentiation = filling containers (fast, reversible, no dopamine). + Short-term depression = containers emptying when the driving signal decays + (passive consequence — never explicit). + +2. TWO PLASTICITY CASES (applies to every component) + Ca²⁺ high → short-term potentiation (fill slots, DAY, local) + Ca²⁺ high + dopamine → set tag → NIGHT raises the slot ceiling (long-term) + +3. THREE COMPETITIVE ECONOMIES, all capped by vascular_glucose_supply + Energy economy: astrocyte cell body → astrosynapses → synaptic budgets (DAY + NIGHT) + Material economy: soma → branches/axon → spines/boutons (NIGHT) + Each: central producer, capped output, demand/tag-weighted distribution. + +4. ABSTRACT BEHAVIORAL PATTERN (every component, every context) + given STRUCTURE (ceiling from last NIGHT) + in CONTEXT (local/global trigger) + if BUDGET sufficient → behavior runs, consumes budget, deposits FAST_TRACE + FAST_TRACE biases next behavior + creates tagging eligibility + eligibility + non-local coincidence → TAG (survives to NIGHT) + traces decay in NOT contexts (depotentiation by neglect, never explicit) + +5. SATURATING RESPONSE FORM (used everywhere a graded signal drives output) + response = signal / (K + signal) + little output at low signal, proportional in middle, saturates when high. + +6. DAY vs NIGHT variable naming + DAY: {component}_budget (fast energy + fast consumables, one variable) + NIGHT: {component}_energy (assembly ATP, NOT recoverable) + {component}_material (structural proteins, RECOVERABLE after LTD) +``` + +--- + +## Part 1 — Conventions + +``` +SCOPE = { DAY, NIGHT } +CONTEXT = { AP, NOT_AP, bAP, NOT_bAP, CONTINUOUS } +COMPONENTS = { PRE, POST, DEND, SOMA, AXON, ASTRO } + +FIXED = imposed externally — constant during run +VAR = changes dynamically +FAST_TRACE = DAY only, decays automatically, biases next behavior +TAG = DAY→NIGHT bridge, decays slowly, gates structural commit + POST: CANDIDATE → STABLE phases +BUDGET = DAY operational resource (energy + consumables) +ENERGY = NIGHT assembly ATP (not recoverable) +MATERIAL = NIGHT structural proteins (recoverable after LTD) +STRUCTURE = capacity ceiling; READ in DAY, WRITTEN in NIGHT +``` + +--- + +## Part 2 — Fixed Parameters + +``` +// Saturation half-points (Option 2 form: x/(K+x)) +FIXED K_Ca_release // half-max Ca²⁺ for NT release +FIXED K_glu_AMPA // half-max glutamate for AMPA current +FIXED K_Ca_Dserine // half-max astro Ca²⁺ for D-serine release + +// Thresholds +FIXED Mg_eject_threshold // Vm to eject NMDA Mg²⁺ block +FIXED Ca_STP_threshold // Ca²⁺ for short-term potentiation (fill slots) +FIXED Ca_TAG_threshold // Ca²⁺ for tagging eligibility +FIXED eligibility_threshold +FIXED dopamine_threshold +FIXED tagging_threshold +FIXED tag_expiry_threshold +FIXED spillover_threshold +FIXED inactivation_threshold // soma Na⁺ inactivation gating refractory +FIXED homeostatic_ceiling +FIXED structural_decay_rate +FIXED recycling_fraction + +// Organism-level signals (externally driven) +FIXED dopamine_level +FIXED NE_level +FIXED ACh_level + +// Physical +FIXED vascular_glucose_supply // hard ceiling — root of energy economy +FIXED branch_geometry // bAP attenuation profile +``` + +--- + +## Part 3 — Resource Variables + +``` +// ── DAY BUDGETS (energy + fast consumables) ─────────────────────────── +VAR astro_budget // ROOT: glycolysis from vascular_glucose_supply (self-produced) +VAR pre_budget // from astro_lactate (primary) + axon shipment (secondary) +VAR post_budget // from astro_lactate (primary) + dend shipment (secondary) +VAR dend_budget // from astro_lactate (primary) + soma shipment (secondary) +VAR soma_budget // ROOT: own mitochondria (self-produced) +VAR axon_budget // from soma shipment (primary) + astro_lactate (secondary) + +// ── ENERGY ECONOMY: astrocyte central → astrosynapses ───────────────── +VAR astro_central_budget // cell body lactate production (DAY) +VAR astro_central_energy // cell body assembly ATP (NIGHT) +VAR astro_central_material // cell body structural proteins (NIGHT) +VAR astro_lactate[i] // demand-weighted export to synapse i (DAY) + +// ── NIGHT ENERGY (assembly ATP, not recoverable) ────────────────────── +VAR pre_energy, post_energy, dend_energy, soma_energy, axon_energy, astro_energy + +// ── NIGHT MATERIAL (structural proteins, recoverable) ───────────────── +VAR soma_material // ROOT: CREB-driven synthesis (soma_tag gated) +VAR dend_material // from soma_material +VAR post_material // from dend_material +VAR axon_material // from soma_material +VAR pre_material // from axon_material +VAR astro_material // from astro_central_material +``` + +--- + +## Part 4 — Structural Variables (capacity ceilings, WRITTEN in NIGHT) + +``` +VAR pre_structure // docking_slot_ceiling + VGCC_coupling + refill_ceiling +VAR post_structure // anchoring_slot_ceiling + spine_volume + reserve_ceiling +VAR dend_structure // bAP_fidelity(position) + translation_ceiling +VAR soma_structure // baseline_threshold⁻¹ + AP_reliability + synthesis_ceiling +VAR axon_structure // propagation_reliability + transport_ceiling +VAR astro_structure // perisynaptic_distance⁻¹ + EAAT_density + D_serine_tonic + // + ECM_integrity (SELF-REINFORCING both directions) +``` + +--- + +## Part 5 — Trace Variables + +``` +FAST_TRACE pre_fast_trace // residual Ca²⁺ τ≈100ms +FAST_TRACE post_fast_trace // spine Ca²⁺ × rise_speed τ≈tens ms +FAST_TRACE dend_fast_trace // branch Ca²⁺ τ≈300ms +FAST_TRACE soma_fast_trace // nuclear Ca²⁺ τ≈seconds +FAST_TRACE axon_fast_trace // propagation load τ≈seconds +FAST_TRACE astro_fast_trace // perisynaptic Ca²⁺ τ≈seconds + +// soma timing traces (emergent refractory + adaptation) +FAST_TRACE soma_Na_inactivation // fast — gates refractory τ≈ms +FAST_TRACE soma_adaptation // slow — spike-train threshold τ≈100s of ms +FAST_TRACE soma_refractory_alignment // bottom-up input-alignment trace + +VAR {component}_possible_tagging // intermediate τ≈seconds–minutes +TAG {component}_tag // slow τ≈hours; POST has CANDIDATE→STABLE +``` + +--- +--- +# SCOPE: DAY +Execution contexts consume budget, deposit traces, fill slots (occupancy). +NOT contexts replenish budget, ship downstream, decay traces, set tags. +STRUCTURE is READ only. + +--- + +## PRE + +### CONTEXT: AP +``` +scope DAY | context AP: + + if pre_budget < AP_release_cost: + suppress(NT_flux); exit context // depleted bouton silent + + // Fast trace: residual Ca²⁺ + pre_fast_trace += spike_Ca_influx(input_freq) + pre_fast_trace *= decay(τ=100ms) + pre_budget -= Ca_handling_cost + + // NT flux — saturating Ca²⁺ drive (Option 2) × current vesicle occupancy + Ca_drive = pre_fast_trace / (K_Ca_release + pre_fast_trace) + if RRP_level > 0: + NT_flux = RRP_level × Ca_drive + glutamate += NT_flux × Δt + RRP_level -= NT_flux × Δt // occupancy falls (STD consequence) + pre_budget -= NT_flux × fusion_cost + + // Refill docking slots — bounded by pre_structure ceiling (DAY fills NIGHT's container) + RRP_refill = min(refill_rate_constant, pre_structure.refill_ceiling) + RRP_level += RRP_refill × Δt + RRP_level = clamp(RRP_level, 0, pre_structure.docking_slot_ceiling) + pre_budget -= RRP_refill × VATPase_cost // throttled if budget low → STD deepens + + // Overflow brake (mGluR2/3 Gi) — cross-compartment, no pre cost + if glutamate > spillover_threshold: + Ca_drive *= mGluR_brake_factor +``` + +### CONTEXT: NOT_AP +``` +scope DAY | context NOT_AP: + + pre_fast_trace *= decay(τ=100ms) + + // Budget replenishment — two sources + pre_budget += astro_lactate[this_synapse] × pre_fraction // primary, fast, local + pre_budget += axon_shipment_to_pre // secondary, from soma via axon + + // Docking slots refill toward ceiling (STP recovery) + RRP_refill = min(refill_rate_constant, pre_structure.refill_ceiling) + RRP_level += RRP_refill × Δt + RRP_level = clamp(RRP_level, 0, pre_structure.docking_slot_ceiling) + pre_budget -= RRP_refill × VATPase_cost + + // Tagging: eligibility (local) + dopamine (non-local) coincide + if pre_fast_trace > eligibility_threshold: + pre_possible_tagging += pre_fast_trace + pre_possible_tagging *= decay(τ=seconds) + dopamine_local *= decay(τ=hundreds_ms) + if dopamine_local > dopamine_threshold and pre_possible_tagging > tagging_threshold: + pre_tag += dopamine_local × pre_possible_tagging + pre_tag *= decay(τ=hours) +``` + +--- + +## POST +Three calcium sources, two plasticity cases + +``` +// Ca²⁺ sources (all feed post_fast_trace): +// 1. AMPA opens → small Ca²⁺ + depolarization (begins ejecting Mg²⁺) +// 2. NMDA opens → large Ca²⁺ (needs: NT bound + D-serine + Mg²⁺ ejected) +// 3. bAP arrives → Ca²⁺ via VDCC + further depolarization +// +// Case 1 (DAY, local): Ca²⁺ high → fill anchoring slots (STP) +// Case 2 (DAY→NIGHT): Ca²⁺ high + dopamine → tag → NIGHT raises slot ceiling +// Depression: surface AMPA drift back to reserve when Ca²⁺ decays (consequence) +``` + +### CONTEXT: NOT_bAP +``` +scope DAY | context NOT_bAP: + + post_budget += astro_lactate[this_synapse] × post_fraction + post_budget += dend_shipment_to_post + + // SOURCE 1: AMPA opens — current + small Ca²⁺ + starts Mg²⁺ ejection + // current saturates with glutamate (Option 2), scaled by surface AMPA occupancy + AMPA_drive = glutamate / (K_glu_AMPA + glutamate) + AMPA_current = AMPA_drive × AMPA_surface // AMPA_surface = current occupancy + Vm += AMPA_current + post_fast_trace += AMPA_Ca_fraction × AMPA_current + post_budget -= AMPA_current_cost + + // SOURCE 2: NMDA opens — large Ca²⁺ if coincidence holds + if Vm > Mg_eject_threshold and astro_D_serine > D_serine_threshold and glutamate > 0: + Ca_influx = NMDA_Ca_influx(glutamate) + post_fast_trace += Ca_influx × rise_speed(Ca_influx) + post_budget -= NMDA_current_cost + + post_fast_trace *= decay(τ=tens_ms) + + // CASE 1 — SHORT-TERM POTENTIATION (no dopamine needed) + // Ca²⁺ high → pull AMPA from reserve to surface, bounded by slot ceiling + if post_fast_trace > Ca_STP_threshold: + AMPA_surface = min(AMPA_surface + Ca_driven_insertion(post_fast_trace), + post_structure.anchoring_slot_ceiling) // DAY fills NIGHT's container + post_budget -= AMPA_trafficking_cost + else: + // CONSEQUENCE — depression: receptors drift back to reserve as Ca²⁺ low + AMPA_surface = max(AMPA_surface - passive_drift_rate × Δt, baseline_surface) + // not explicit, not signaled — pure relaxation toward baseline occupancy + + // CASE 2 — tagging for long-term (CANDIDATE) + if post_fast_trace > Ca_TAG_threshold: + post_possible_tagging += post_fast_trace + post_possible_tagging *= decay(τ=minutes) // CANDIDATE lifetime + post_budget -= PKA_priming_cost + + dopamine_local *= decay(τ=hundreds_ms) + if dopamine_local > dopamine_threshold and post_possible_tagging > tagging_threshold: + post_tag += dopamine_local × post_possible_tagging // STABLE + post_tag *= decay(τ=hours) +``` + +### CONTEXT: bAP +``` +scope DAY | context bAP: + + // SOURCE 3: bAP — depolarization + Ca²⁺, amplifies existing signal + Vm += bAP_depolarization × dend_structure.bAP_fidelity + post_budget -= bAP_reset_cost + if post_possible_tagging > Ca_TAG_threshold: // coincidence: bAP finds CANDIDATE + post_fast_trace += bAP_Ca_boost() // supralinear summation > Ca_HIGH + // bAP alone with no prior Ca²⁺ → no boost, no tag (timing enforced by trace decay) +``` + +--- + +## DEND + +### CONTEXT: bAP +``` +scope DAY | context bAP: + + bAP_local = propagate_bAP(SOMA.AP_fired, dend_structure.bAP_fidelity, branch_geometry) + dend_budget -= bAP_propagation_cost + dend_fast_trace += bAP_Ca_influx(bAP_local) + spine_Ca_spillover(active_spines) + dend_fast_trace *= decay(τ=300ms) + dend_budget -= branch_Ca_handling_cost + branch_Vm = integrate(POST.Vm, all_spines) + dend_budget -= integration_cost +``` + +### CONTEXT: NOT_bAP +``` +scope DAY | context NOT_bAP: + + dend_fast_trace *= decay(τ=300ms) + + // Replenish (from soma + astrocyte), then ship to spines + dend_budget += soma_shipment_to_dend + astro_lactate[this_branch] × dend_fraction + dend_shipment_to_post = min(dend_budget × post_delivery_fraction, post_demand) + post_budget += dend_shipment_to_post + dend_budget -= dend_shipment_to_post + + // Tagging + if dend_fast_trace > eligibility_threshold: + dend_possible_tagging += dend_fast_trace + dend_possible_tagging *= decay(τ=seconds) + dopamine_local *= decay(τ=hundreds_ms) + if dopamine_local > dopamine_threshold and dend_possible_tagging > tagging_threshold: + dend_tag += dopamine_local × dend_possible_tagging + dend_tag *= decay(τ=hours) + + // Local translation (fills dend capacity faster) if tagged + budget + if dend_tag > tag_expiry_threshold and dend_budget > translation_cost: + dend_budget -= translation_cost // uses fast mRNA consumables in budget + + commit_threshold *= 1 / (1 + ACh_level × ACh_gain) +``` + +--- + +## SOMA +Emergent refractory + adaptation + bottom-up input alignment + +### CONTEXT: AP +``` +scope DAY | context AP: + + // Threshold = baseline(structure) raised by adaptation + neuromodulators + effective_threshold = soma_structure.baseline_threshold + × (1 + soma_adaptation) + × neuromod_factor(NE_level, ACh_level) + can_fire = (soma_Na_inactivation < inactivation_threshold) // refractory = emergent + + if branch_Vm > effective_threshold and can_fire: + AP_fired = True + soma_budget -= AP_generation_cost + + // Deposit three traces from one AP: + soma_Na_inactivation += AP_amplitude // fast → refractory gating + soma_adaptation += AP_contribution // slow → spike-train threshold rise + soma_fast_trace += nuclear_Ca_influx() // slow → plasticity tagging + soma_budget -= nuclear_Ca_handling_cost + + if soma_fast_trace > eligibility_threshold: + soma_possible_tagging += soma_fast_trace + soma_possible_tagging *= decay(τ=seconds) + dopamine_local *= decay(τ=hundreds_ms) + if dopamine_local > dopamine_threshold and soma_possible_tagging > tagging_threshold: + soma_tag += dopamine_local × soma_possible_tagging + soma_tag *= decay(τ=hours) + soma_budget -= CREB_phosphorylation_cost +``` + +### CONTEXT: NOT_AP +``` +scope DAY | context NOT_AP: + + // BOTTOM-UP ALIGNMENT: suprathreshold input during refractory = missed coincidence + // leaves a trace that speeds future recovery (potentiation of recovery, DAY) + if branch_Vm > effective_threshold and soma_Na_inactivation > inactivation_threshold: + soma_refractory_alignment += (branch_Vm - effective_threshold) × soma_Na_inactivation + + // Recovery biased by alignment trace; alignment decays (depotentiation by neglect) + recovery_rate = base_recovery_rate × (1 + soma_refractory_alignment) + soma_Na_inactivation *= decay(τ_Na / recovery_rate) + soma_adaptation *= decay(τ_adaptation) + soma_fast_trace *= decay(τ_nuclear) + soma_refractory_alignment *= decay(τ_alignment) // self-limiting equilibrium + + // Self-replenish (own mitochondria) — soma is a root + soma_budget += mitochondria_output_rate × Δt + branch_Vm = integrate(DEND.branch_Vm, all_branches) + + // Ship budget downstream + soma_shipment_to_dend = min(soma_budget × dend_delivery_fraction, dend_demand(dend_tag)) + dend_budget += soma_shipment_to_dend; soma_budget -= soma_shipment_to_dend + shipping_cost + soma_shipment_to_axon = min(soma_budget × axon_delivery_fraction, axon_demand(axon_tag)) + axon_budget += soma_shipment_to_axon; soma_budget -= soma_shipment_to_axon + shipping_cost +``` + +--- + +## AXON + +### CONTEXT: AP +``` +scope DAY | context AP: + + propagation_reliability = axon_structure.propagation × (1 - failure_rate(axon_fast_trace)) + APs_delivered = AP_fired × propagation_reliability + axon_budget -= AP_propagation_cost × APs_delivered + axon_fast_trace += APs_delivered + axon_fast_trace *= decay(τ=seconds) // high load → failure → axonal STD +``` + +### CONTEXT: NOT_AP +``` +scope DAY | context NOT_AP: + + axon_fast_trace *= decay(τ=seconds) + axon_budget += soma_shipment_to_axon + astro_lactate[shaft] × axon_fraction + + // Ship to boutons + axon_shipment_to_pre = min(axon_budget × pre_delivery_fraction, pre_demand(pre_tag)) + pre_budget += axon_shipment_to_pre; axon_budget -= axon_shipment_to_pre + axon_shipping_cost + + if axon_fast_trace > eligibility_threshold: + axon_possible_tagging += axon_fast_trace + axon_possible_tagging *= decay(τ=seconds) + dopamine_local *= decay(τ=hundreds_ms) + if dopamine_local > dopamine_threshold and axon_possible_tagging > tagging_threshold: + axon_tag += dopamine_local × axon_possible_tagging + axon_tag *= decay(τ=hours) +``` + +--- + +## ASTRO +Demand-weighted energy distribution across the territory + +### CONTEXT: CONTINUOUS +``` +scope DAY | context CONTINUOUS: + + // ROOT production at cell body — capped by vasculature + astro_central_budget += glycolysis(vascular_glucose_supply) × Δt + + // DEMAND-WEIGHTED LACTATE ALLOCATION across all astrosynapses i + // demand rises with clearance load (activity) AND delivery efficiency (structure) + for each astrosynapse i in territory: + demand[i] = clearance_load[i] × astro_structure[i].delivery_efficiency + total_demand = sum(demand) + allocation_factor = min(1, astro_central_budget / (total_demand × lactate_cost + ε)) + for each astrosynapse i: + astro_lactate[i] = demand[i] × allocation_factor // slow synapse → low demand → little fuel + astro_central_budget -= astro_lactate[i] × lactate_cost + // delivered to that synapse's pre/post/dend budgets in their NOT contexts + + // Per-astrosynapse fast operation (one synapse i shown) + glutamate[i] -= astro_structure[i].EAAT_density × glutamate[i] × Δt // clearance + astro_central_budget -= clearance × EAAT_ATP_cost + astro_D_serine[i] += astro_structure[i].D_serine_tonic × Δt // tonic baseline + + if glutamate[i] > spillover_threshold: + astro_fast_trace[i] += mGluR5_Ca_influx() + astro_fast_trace[i] *= decay(τ=seconds) + // D-serine pulse — saturating in astro Ca²⁺ (Option 2), budget-limited + Ds_drive = astro_fast_trace[i] / (K_Ca_Dserine + astro_fast_trace[i]) + D_serine_pulse = min(Ds_drive × Ds_max, astro_central_budget × Ds_fraction) + astro_D_serine[i] += D_serine_pulse + astro_central_budget -= D_serine_pulse × Ds_synthesis_cost + Ca_drive_pre[i] *= mGluR_brake_factor // simultaneous PRE brake + + if astro_fast_trace[i] > eligibility_threshold: + astro_possible_tagging[i] += astro_fast_trace[i] + astro_possible_tagging[i] *= decay(τ=seconds) + dopamine_local *= decay(τ=hundreds_ms) + if dopamine_local > dopamine_threshold and astro_possible_tagging[i] > tagging_threshold:varie + astro_tag[i] += dopamine_local × astro_possible_tagging[i] + astro_tag[i] *= decay(τ=hours) + + if astro_fast_trace[i] > OVERLOAD_threshold: + trigger(shockwave_lockdown) +``` + +--- +--- +# SCOPE: NIGHT +NIGHT builds containers (raises ceilings). Budgets/energy/material replenished. +Tags evaluated and cleared. Depotentiation = unmaintained decay (never explicit). + +--- + +## Step 1 — Replenish & Distribute (two economies) + +``` +scope NIGHT | step 1: + + // ── ENERGY ECONOMY: astrocyte cell body → astrosynapses ───────────── + astro_central_budget += overnight_glycolysis(vascular_glucose_supply) × Δt_night + astro_central_energy += overnight_astro_energy_synthesis() × Δt_night + astro_central_material += astrocyte_cellbody_synthesis() × Δt_night + + // distribute to tagged astrosynapses by astro_tag-weighted competition + total_w = sum(astro_tag[i] for taggable i) + for each astrosynapse i with astro_tag[i] > tag_expiry_threshold: + w = astro_tag[i] / total_w + astro_energy[i] += astro_central_energy × w + astro_material[i] += astro_central_material × w + astro_central_energy -= astro_energy[i]; astro_central_material -= astro_material[i] + + // ── MATERIAL ECONOMY: soma → branches/axon → spines/boutons ───────── + soma_budget += overnight_mitochondria_output() × Δt_night + soma_energy += overnight_soma_energy_reserve() × Δt_night + soma_material += CREB_driven_synthesis(soma_tag) × Δt_night // bottleneck, soma_tag gated + + dend_material += soma_material × dend_material_fraction + axon_material += soma_material × axon_material_fraction + soma_material -= (dend_material_fraction + axon_material_fraction) × soma_material + post_material += dend_material × spine_material_fraction; dend_material -= ... + pre_material += axon_material × bouton_material_fraction; axon_material -= ... + + // downstream assembly energy from soma; next-DAY budgets pre-loaded from astrocyte + {pre,post,dend,axon}_energy += soma_energy × {..}_energy_fraction + {pre,post,dend,axon}_budget += astro_lactate_reserve × {..}_fraction × Δt_night +``` + +## Step 2 — Structural Commits (build containers; parallel, independent) + +``` +scope NIGHT | step 2: + + coherence_bonus = (pre_tag, post_tag, astro_tag all > tag_expiry_threshold) + ? coherence_factor : 1.0 + + // each commit RAISES A CEILING (capacity), gated by tag, material, energy + // DAY then fills the raised ceiling via calcium-driven occupancy + + if pre_tag > tag_expiry_threshold: + Δ = min(slot_cost, pre_material, pre_energy × pre_fraction) + pre_structure.docking_slot_ceiling += Δ × coherence_bonus // MORE slots, not more vesicles + pre_material -= Δ; pre_energy -= Δ × assembly_cost + if Δ < slot_cost: queue(pre_deficit → next NIGHT) + + if post_tag > tag_expiry_threshold: + Δ = min(slot_cost, post_material, post_energy × post_fraction) + post_structure.anchoring_slot_ceiling += Δ × coherence_bonus // MORE slots for DAY to fill + post_material -= Δ; post_energy -= Δ × assembly_cost + if Δ < slot_cost: queue(post_deficit → next NIGHT) + + if dend_tag > tag_expiry_threshold: + Δ = min(branch_cost, dend_material, dend_energy × dend_fraction) + dend_structure += Δ × coherence_bonus + dend_material -= Δ; dend_energy -= Δ × assembly_cost + + if soma_tag > tag_expiry_threshold: + Δ = min(soma_cost, soma_material, soma_energy × soma_fraction) + soma_structure += Δ + soma_material -= Δ; soma_energy -= Δ × assembly_cost + + if axon_tag > tag_expiry_threshold: + Δ = min(axon_cost, axon_material, axon_energy × axon_fraction) + axon_structure += Δ + axon_material -= Δ; axon_energy -= Δ × assembly_cost + + if astro_tag[i] > tag_expiry_threshold: + Δ = min(process_cost, astro_material[i], astro_energy[i] × astro_fraction) + astro_structure[i] += Δ × coherence_bonus // walls IN, ECM, D-serine tonic ↑ + astro_material[i] -= Δ; astro_energy[i] -= Δ × assembly_cost + // SELF-REINFORCING: higher astro_structure → future LTP easier +``` + +## Step 3 — Passive Depotentiation (unmaintained decay) + +``` +scope NIGHT | step 3: + + remaining_material = total_material_pool - material_consumed_by_commits + maintenance_per_syn = remaining_material × maintenance_fraction / synapse_count + + for each synapse: + // all ceilings decay + {pre,post,dend,astro}_structure -= structural_decay_rate × Δt_night + // maintenance counters decay only where resources suffice + if maintenance_per_syn >= maintenance_cost: + {pre,post,dend,astro}_structure += full_maintenance // stable + else: + {pre,post,dend,astro}_structure += maintenance_per_syn × fractions + // shortfall → ceilings drift down → DEPOTENTIATION BY NEGLECT + + // material (not energy) recovered from shrinking structures → back to pools + for each synapse with net_structure_change < 0: + recovered = |net_structure_change| × recycling_fraction + {pre,post,astro}_material += recovered × fractions +``` + +## Step 4 — Homeostatic Scaling + +``` +scope NIGHT | step 4: + + if soma_tag > homeostatic_ceiling: + s = homeostatic_ceiling / soma_tag + for each synapse: + post_structure.anchoring_slot_ceiling *= s + pre_structure.docking_slot_ceiling *= s + soma_material += sum(ceiling_reduction) × recycling_fraction +``` + +## Step 5 — Clear Traces + +``` +scope NIGHT | step 5: + + all fast_traces = 0 + all possible_tagging = 0 + soma_Na_inactivation = soma_adaptation = soma_refractory_alignment = 0 + for each tag: if tag < tag_expiry_threshold: tag = 0 // else carry to next NIGHT +``` + +--- + +## Summary — the model in one view + +``` +DAY fills containers (occupancy ↑ with Ca²⁺, ↓ when Ca²⁺ decays = STP/STD) + consumes budget; budget from astrocyte (demand-weighted) + soma shipments + deposits fast traces; eligibility + dopamine coincidence → tags +NIGHT builds containers (ceilings ↑) for tagged synapses, by two competing economies: + energy (astrocyte→astrosynapse) and material (soma→spine/bouton) + unmaintained ceilings decay → depotentiation by neglect + recovered material funds neighbors → conservation across the territory + +Joint criterion to be remembered: + active enough to be FUELED (win energy economy, generate Ca²⁺ + clearance demand) + + significant enough to be TAGGED (Ca²⁺ + dopamine coincidence) + → container built in NIGHT, filled in DAY, maintained while still earning resources +``` + + + +--- +--- +--- + +# Flows + +Per ora abbiamo in DAY il {component}_budget che raggruppa energy e material, e in NIGHT {component}_energy e {component}_material. + +This maps onto a real biological distinction. The astrocyte's lactate and the soma's ATP fund the running costs of the cell — everything that needs to happen just to keep the system operating from moment to moment. CREB-driven protein synthesis funds the capital investment — the slow, expensive structural changes that modify what the running system is capable of. These are two different budgets in the biological sense: operating expenditure versus capital expenditure. Combining them within DAY is correct because DAY is entirely operating expenditure. Keeping them separate in NIGHT is correct because NIGHT mixes operating expenditure with capital expenditure, and only the capital component is recoverable. + +Combining {component}_energy e {component}_material would hide the fact that dismantling a structure recovers biological building blocks but not the work that was done to assemble them — which is the thermodynamic reality of any construction and deconstruction process. + + +## Energy flow + +``` +VASCULAR SUPPLY + → ASTROCYTE CELL BODY + glucose → lactate (glycolysis) + → astro_budget (local ATP for clearance, D-serine, ECM, process motility) + → lactate exported to: + → pre_budget (ATP for VGCC, vesicle fusion, VATPase) + → post_budget (ATP for NaK pump, AMPA trafficking, actin) + → dend_budget (ATP for bAP propagation, local translation) + + → SOMA + soma has own mitochondria — partly self-fueled + soma_budget (ATP for AP generation, CREB, protein synthesis, shipping) + → dend_budget top-up (organelle delivery) + → axon_budget top-up (transport machinery) +``` + +## Material flow + +``` +SOMA + protein synthesis (CREB-driven, peaks in NIGHT) + → soma_material (receptors, scaffold proteins, organelles, mRNA) + → dend_material (branch receives proteins + mRNA from soma) + → post_material (spine receives receptors + actin from branch) + → axon_material (boutons receive AZ proteins + VGCCs from soma via axon) + → pre_material (bouton active zone proteins) + +ASTROSYNAPSE + ECM proteins synthesized in astrocyte cell body + → astro_material (Glypicans, Thrombospondins, serine for D-serine) + → cleft environment (ECM sealing, D-serine availability) +``` + +Yes, exactly. This is the essential abstract pattern. Let me state it precisely. + +# The Abstract Pattern + +A component operates within a structure set by the previous NIGHT. During DAY, in each context, it executes behaviors that cost budget and deposit fast traces. Fast traces are local records of recent activity that bias the next behavior and open an eligibility window for tagging. A tag forms when a local eligibility signal coincides with one or more non-local validation signals within the decay window of the trace — the number of required coincidences reflecting the spatial scale at which that component sits in the system. In contexts without triggering input, all traces decay, closing the windows they opened. At NIGHT, the tag magnitude drives a structural commit proportional to available material and energy — material being recoverable and energy not — with the structural change becoming the new ceiling within which the next DAY's behaviors will operate. What is not committed decays for lack of maintenance, and the resources freed by that decay partially fund the potentiation of what was. + +## DAY — The General Form + +Every DAY behavior follows this template: + +``` +given: STRUCTURE // the architectural ceiling left by NIGHT +in: CONTEXT // local or global triggering condition +if: BUDGET > cost // operational resources available +then: behavior executes + BUDGET -= cost // resources consumed + FAST_TRACE += f(behavior) // local record deposited +``` + +The fast trace then drives two parallel processes: + +**Within the same context** — the trace biases the next execution of the same behavior. This is the short-term modulation loop. It is entirely local and requires no external signal. + +**Across contexts** — the trace accumulates into `possible_tagging` when it exceeds the eligibility threshold. This is the bridge toward long-term change. It requires the trace to be sustained enough to survive into the NOT_AP or CONTINUOUS context. + +### The Tag Formation — Where Non-Locality Enters + +The abstract pattern for tag formation generalizes across all components but with different **coincidence requirements**: + +**PRE, DEND, SOMA, AXON, ASTRO — one non-local coincidence:** +``` +if FAST_TRACE > eligibility // local: this bouton was recently active + AND dopamine > threshold // non-local: organism-level reward signal +then: TAG += dopamine × possible_tagging +``` +One spatial scale beyond the local component is required. The organism must confirm that the recent activity was worth saving. + +**POST — two non-local coincidences:** +``` +// First coincidence (NOT_bAP context): +if FAST_TRACE > Ca_TAG_threshold // local: spine Ca²⁺ was high + AND D-serine > threshold // non-local 1: astrosynapse co-agonist +then: post_possible_tagging += FAST_TRACE // CANDIDATE + +// Second coincidence (bAP context): +if post_possible_tagging > threshold // local: CANDIDATE still present + AND bAP arrives // non-local 2: soma fired +then: FAST_TRACE amplified above Ca_HIGH + +// Tag stabilization (any context): +if post_possible_tagging > threshold // local: confirmed coincidence + AND dopamine > threshold // non-local 3: organism validation +then: TAG += dopamine × post_possible_tagging // STABLE +``` +Three spatial scales must align: astrosynapse, soma, organism. The postsynapse is the most constrained component — it requires the most non-local validation before committing. + +### Trace Recession — The Temporal Behavior + +In every NOT_AP or CONTINUOUS context, all traces decay: + +``` +FAST_TRACE *= decay(τ_fast) // ms to seconds — closes eligibility window +possible_tagging *= decay(τ_mid) // seconds to minutes — closes tagging window +TAG *= decay(τ_slow) // hours — closes commitment window +``` + +The decay is not a separate behavior — it is the passive consequence of molecular processes. But its effect is behavioral: it enforces that coincidences must happen within specific time windows. The system does not check timing explicitly — timing is enforced by the competition between accumulation and decay. + +## NIGHT — The General Form + +``` +given: TAG // strength of DAY evidence for this component + STRUCTURE // current architectural state +if: TAG > threshold // evidence strong enough to justify investment +then: + Δstructure = min(expansion_cost, + MATERIAL, // slow structural resources available + ENERGY × fraction) // assembly ATP available + STRUCTURE += Δstructure × coherence_bonus + MATERIAL -= Δstructure // RECOVERABLE after LTD + ENERGY -= Δstructure × ATP_cost // NOT recoverable +``` + +The coherence bonus appears when pre, post, and astro tags are all SET simultaneously — the three components of the synapse have all independently gathered evidence for the same structural change, which amplifies the commit beyond what any single tag would produce alone. + +What is not potentiated passively decays: + +``` +STRUCTURE -= decay_rate × Δt_night +STRUCTURE += min(maintenance_allocation, maintenance_cost) +// if maintenance_allocation < decay_rate × Δt_night: +// structure drifts down — depotentiation by neglect +``` + +# More details + +## SOMA + +### The Abstract Pattern Applied to Soma Timing + +The abstract pattern says: a behavior deposits a trace, the trace decays, and the trace biases the next behavior. For the soma, the AP is the behavior, and **the refractory period and threshold elevation should both be consequences of a single trace deposited by the AP, decaying back toward baseline**. Neither should be a hardcoded duration — both should emerge from the return of the trace to resting conditions. + +--- + +Yes, this is much more consistent with the rest of the architecture. The soma should not compute an explicit rhythm estimate and predict the next input — that is top-down. Instead, the **mismatch itself leaves a trace**, and that trace adjusts the refractory dynamics. Let me think through this carefully. + +--- + +### The Bottom-Up Mechanism + +The key event is: **a dendritic input arrives strong enough to fire the soma, but the soma is still refractory.** This is a missed opportunity — the input wanted to fire the cell, but the cell was not ready. This mismatch is the signal. + +Each time this happens, it should leave a trace that biases the refractory dynamics toward recovering faster in that timing window — so that next time an input arrives at that phase, the soma is ready. This is potentiation of the refractory recovery, occurring within DAY, driven entirely by the local coincidence of "input wanted to fire" and "soma was not ready." + +``` +scope DAY | context NOT_AP (within refractory): + + // Detect the mismatch: suprathreshold input during refractory + if branch_Vm > effective_threshold and soma_Na_inactivation > inactivation_threshold: + // Input arrived but soma could not fire — missed coincidence + refractory_alignment_trace += (branch_Vm - effective_threshold) + × soma_Na_inactivation + // graded: stronger input + deeper refractory → larger trace + // this is the "potentiation" signal for faster recovery +``` + +The `refractory_alignment_trace` then biases the recovery rate of the inactivation trace: + +``` + // Recovery rate biased by accumulated alignment trace + recovery_rate = base_recovery_rate × (1 + refractory_alignment_trace) + soma_Na_inactivation *= decay(τ_Na / recovery_rate) + // more alignment trace → faster recovery → soma ready sooner next time +``` + +--- + +### Why This Is Bottom-Up + +There is no rhythm estimation, no prediction of the next input time, no computed inter-input interval. The soma does not model its input. It simply notices, locally and reactively, that an input arrived when it was not ready, and leaves a trace that makes it recover faster. Over many such mismatches at the same phase, the recovery speeds up at that phase specifically — and the soma ends up aligned with its input rhythm **without ever representing that rhythm**. + +The alignment is an emergent statistical consequence of many local mismatch events, exactly as a potentiated synapse becomes tuned to its input without representing what it is tuned to. The phase-coupling appears, but nothing in the soma computed it. + +--- + +### Depotentiation as Neglect — Not Explicit + +Now the crucial part you raised: the depotentiation of refractory alignment must occur as a **consequence of not potentiating**, not as an explicit opposing mechanism. + +The `refractory_alignment_trace` decays continuously. If mismatches keep happening at a particular phase, the trace is continuously replenished and the fast recovery is maintained. If mismatches stop happening — because the input rhythm changed, or because the alignment succeeded and inputs now arrive when the soma is ready — then the trace is no longer replenished and **decays back toward baseline on its own**. + +``` + // No explicit depotentiation — just decay when not reinforced + refractory_alignment_trace *= decay(τ_alignment) + // if mismatches continue → trace replenished → fast recovery maintained + // if mismatches stop → trace decays → recovery returns to baseline +``` + +This is exactly parallel to synaptic depotentiation by neglect. The soma does not actively slow its recovery when alignment is no longer needed. It simply stops receiving the mismatch signal that was keeping the recovery fast, and the recovery drifts back to baseline because the trace that accelerated it is no longer reinforced. + +There is an elegant self-limiting property here. Once the soma is well-aligned, inputs arrive when it is ready, so there are no more mismatches, so the alignment trace stops being replenished and begins to decay. This would slowly de-align the soma — until inputs start arriving during refractory again, regenerating the mismatch and re-potentiating the alignment. The system settles into a dynamic equilibrium where just enough mismatch occurs to maintain just enough alignment. The soma hovers at the edge of alignment, continuously corrected by the residual mismatches that its imperfect alignment produces. + +--- + +### The Full Bottom-Up Soma Timing + +``` +scope DAY | context AP: + + effective_threshold = soma_structure.baseline_threshold + × (1 + soma_adaptation) + × neuromod_factor(NE_level, ACh_level) + + can_fire = (soma_Na_inactivation < inactivation_threshold) + + if branch_Vm > effective_threshold and can_fire: + AP_fired = True + soma_budget -= AP_generation_cost + + // Deposit traces from the AP + soma_Na_inactivation += AP_amplitude // fast — refractory + soma_adaptation += AP_contribution // slow — spike train threshold + soma_fast_trace += nuclear_Ca_influx() // slow — plasticity tagging + +scope DAY | context NOT_AP: + + // MISMATCH DETECTION — bottom-up alignment signal + if branch_Vm > effective_threshold and soma_Na_inactivation > inactivation_threshold: + // input wanted to fire but soma was refractory — missed coincidence + refractory_alignment_trace += (branch_Vm - effective_threshold) + × soma_Na_inactivation + // local potentiation of recovery — no prediction, no rhythm model + + // Recovery biased by alignment trace + recovery_rate = base_recovery_rate × (1 + refractory_alignment_trace) + soma_Na_inactivation *= decay(τ_Na / recovery_rate) // faster if aligned + soma_adaptation *= decay(τ_adaptation) + soma_fast_trace *= decay(τ_nuclear) + + // Alignment trace decays — depotentiation by neglect, not explicit + refractory_alignment_trace *= decay(τ_alignment) + // maintained only while mismatches continue + // self-limiting: good alignment → fewer mismatches → trace decays → + // slight de-alignment → mismatches return → re-potentiation + + // ... budget replenishment, shipments, tagging as before ... +``` + +--- + +### The Conceptual Payoff + +This makes the soma's temporal alignment obey exactly the same principles as everything else in the system: + +A behavior leaves a trace — here the missed coincidence leaves the alignment trace. + +The trace biases future behavior — here it accelerates recovery so the next input at that phase succeeds. + +Potentiation is the active drive — the soma actively speeds up recovery in response to mismatch. + +Depotentiation is neglect — the alignment trace decays when mismatches stop, with no explicit opposing process. + +The system finds equilibrium through the residual of its own imperfection — just enough mismatch persists to maintain just enough alignment. + +And critically, the soma achieves temporal prediction — firing in phase with its input rhythm — **without ever representing the rhythm**. The prediction is implicit in the structure of the recovery dynamics, built up from purely local, reactive, bottom-up trace deposits. This is the same way a potentiated synapse "predicts" that its input will be significant without representing the prediction: the prediction is the physical bias left by past experience, not a computed expectation. The soma's phase-coupling is the temporal version of the synapse's weight — both are implicit predictions encoded as physical bias, both built bottom-up from local coincidence, both maintained by reinforcement and lost by neglect. + +## Energy depletion in Presynapse + +how does the budget and energy influence the model. If for example a presynapse has no more energy variuos times during day, what happens? + +Good question. Let me trace through exactly what happens when energy is repeatedly depleted, following the mechanics already in the pseudocode. + +--- + +### The Immediate Effect — Behavior Suppression + +When `pre_budget < AP_release_cost`, the pseudocode does: + +``` +if pre_budget < AP_release_cost: + suppress(NT_flux) + exit context +``` + +So the immediate consequence of an energy-depleted bouton is **silence** — it does not release neurotransmitter for that AP, regardless of how strong the incoming spike was. The AP arrives, but nothing comes out the other side. This is biologically real: ATP-depleted boutons fail to release because the VATPase cannot refill vesicles and the calcium pumps cannot maintain the gradients that drive release. + +--- + +### The Cascade of Consequences Within DAY + +A single depletion is recoverable — the bouton refuels from astrocyte lactate in the next NOT_AP context and resumes. But **repeated depletion during DAY** sets off a cascade that runs through the entire trace and tagging machinery. + +**No release means no glutamate means no downstream trace.** When the bouton is silent, no glutamate reaches the cleft. The postsynapse receives no AMPA current, its NMDA channels do not open, and `post_fast_trace` does not rise. The astrosynapse detects no spillover, so `astro_fast_trace` does not rise and no D-serine pulse is released. The entire synaptic event simply does not happen. A bouton that is energy-depleted at the moment a significant pattern arrives causes that pattern to be invisible to the postsynapse — the synapse fails to participate in whatever the network is doing. + +**No participation means no eligibility.** Because the bouton did not release, `pre_fast_trace` is not elevated by a release event (it still rises from calcium influx, but without the reinforcing facilitation of successful release). More importantly, the postsynapse, having received no input, accumulates no `post_possible_tagging`. When dopamine arrives to validate the moment, there is nothing to validate at this synapse — the eligibility window is empty. The synapse misses the tagging opportunity entirely. + +**Missing the tag means missing the NIGHT commit.** Since no tag was set during DAY, the synapse has nothing to draw structural resources with during NIGHT. It does not potentiate. And because the system's depotentiation is by neglect, **a synapse that fails to potentiate is automatically on the path to depotentiation** — it receives only maintenance allocation, and if other synapses potentiated and drew down the shared pool, even maintenance may be insufficient. + +--- + +### The Deeper Consequence — Energy Depletion Becomes Structural Depression + +Here is the important emergent property: **repeated energy depletion at a bouton during DAY leads to its structural depression during NIGHT, even though no depression signal was ever sent.** + +The chain is entirely passive: + +``` +repeated pre_budget depletion in DAY + → bouton silent during significant events + → no glutamate release + → no post_fast_trace, no post_possible_tagging + → no tag set (pre or post) + → no NIGHT structural commit at this synapse + → only maintenance allocation received + → if pool depleted by other synapses' potentiation: + maintenance insufficient + → pre_structure and post_structure decay + → DEPOTENTIATION +``` + +The energy-starved synapse is outcompeted not because it was marked for depression but because it could not generate the activity needed to claim resources. Energy availability during DAY therefore directly determines which synapses can even enter the competition for NIGHT potentiation. + +--- + +### The Feedback Loop — Depression Reduces Future Energy Demand + +There is a stabilizing feedback here. A depotentiated synapse has smaller `pre_structure` — a smaller active zone, fewer docking slots, lower release probability. This means it costs **less energy to operate**. So a synapse that was energy-starved and consequently depotentiated now has lower energy demands, making it less likely to be energy-starved in the future. + +``` +energy depletion → depotentiation → smaller structure → lower energy demand + → less likely to deplete → stabilizes at a low-activity equilibrium +``` + +The synapse settles into a low-energy, low-structure, low-activity state. It is not dead — it still operates at baseline — but it has been demoted from the pool of synapses competing for potentiation. Energy scarcity has selected it out. + +--- + +### Why This Is Functionally Important + +This is not a bug — it is a resource-allocation mechanism with real computational value. + +**Energy availability acts as a second gate on plasticity, parallel to the neuromodulatory gate.** Dopamine asks "was this worth saving?" Energy asks "can this synapse afford to participate?" A synapse must pass both gates to be potentiated. This means the system preferentially potentiates synapses that are both behaviorally significant AND metabolically sustainable. A synapse that cannot sustain its own activity is not a good candidate for strengthening, because strengthening it would only increase its energy demand and make it fail more often. + +**Local energy competition implements a form of spatial sparsification.** Boutons on the same axon share `axon_budget` and ultimately the same astrocytic lactate supply. When many boutons are active simultaneously, the shared energy is divided among them, and the weakest — those with the least efficient structure or the least reliable input — deplete first and fall silent. This automatically sparsifies activity: under energy pressure, only the most robust synapses keep firing, and they are the ones that get potentiated. The system concentrates its limited resources on its strongest connections. + +**The astrocyte's energy delivery becomes a control signal.** Because the astrocyte controls lactate distribution across its territory, it has indirect control over which synapses can sustain activity and therefore which can be potentiated. A region of the astrocyte territory that is well-perfused and well-fueled supports vigorous plasticity. A region that is metabolically stressed — perhaps because of high overall demand or reduced vascular supply — suppresses plasticity in its synapses regardless of their activity. This couples the metabolic state of the tissue directly to its capacity to learn. + +--- + +### What Repeated Depletion Looks Like Over Days + +If a bouton is chronically energy-starved across multiple DAY cycles — perhaps because it is in a metabolically compromised region, or because it is competing with many highly active neighbors — the trajectory is: + +``` +Day 1: depletes occasionally → misses some events → weak tag → partial commit +Day 2: smaller structure → still depletes under load → weaker tag → less commit +Day 3: structure decaying → maintenance insufficient → depotentiation accelerates +... +Equilibrium: minimal structure, minimal energy demand, minimal participation + synapse survives but is functionally silent + resources it would have consumed now available to neighbors +``` + +This is a reasonable model of what happens to synapses in metabolically stressed tissue — they do not die immediately, but they are progressively silenced and depotentiated, freeing their resources for synapses in healthier regions. It is also a model of how chronic metabolic limitation — aging, vascular disease, mitochondrial dysfunction — would manifest as a gradual loss of plasticity capacity: not through any depression signal, but through the simple inability of energy-starved synapses to participate in the activity that would let them claim resources. + +The energy budget is therefore not just a constraint that occasionally blocks behavior — it is a continuous selective pressure that shapes which synapses thrive and which fade, operating silently in parallel with the explicit activity-and-reward-driven plasticity, and ultimately determining the metabolic sustainability of whatever the system chooses to remember. + +## Three parallel competitive resource economies +The neuronal structural economy — soma produces material, distributed through dendrite to spines and through axon to boutons, competed for by tagged synapses during NIGHT. +The astrocytic energy economy — astrocyte cell body produces lactate, distributed to perisynaptic processes, competed for by active synapses during DAY in proportion to their clearance demand. +The soma's own energy economy — soma mitochondria fuel AP generation and shipping, competed for by the soma's own functions. +All three share the same logic: a central producer with a capped output, distribution to peripheral consumers, demand-weighted allocation, and a self-reinforcing coupling where stronger consumers both demand and receive more. And all three ultimately bottom out at the same vascular glucose ceiling — the astrocyte directly, the soma through its own glucose uptake. +The deep consequence is that a synapse must win on both economies to be potentiated. It must generate enough activity to pull lactate from the astrocyte (energy economy) AND accumulate enough tag to draw material during NIGHT (structural economy). A synapse that wins the structural competition but cannot pull energy will be unable to sustain the activity that justified its potentiation — it will be a large, expensive structure that keeps going silent. A synapse that pulls energy but never accumulates a tag stays metabolically supported but structurally weak. Only synapses that win both — active enough to be fueled, significant enough to be tagged — achieve and maintain full potentiation. The two economies together implement a stringent joint criterion: persistent significant activity that the metabolic infrastructure can sustain.