System and method for bidirectional memory R/W via closed-loop processing.

The BCI Memory Read and Write System is a closed-loop brain–computer interface for reading and writing episodic memory. It detects, decodes, and selectively amplifies hippocampal replay during encoding and consolidation, and injects manifold-constrained engram patterns for de novo memory synthesis and reconsolidation editing. It unifies three natural memory timescales — 10 ms spike bursts, the 1–2 hr synaptic tagging window, and multi-night systems consolidation — under one decoder.

Closed-loop latency
< 18 ms
SWR detect → stim onset, Tier 1
Write fidelity
0.81 r
predicted vs. measured engram, n=24
Index dimensionality
1,024
sparse pointer, k=48 active
Voxel coverage
286k
1.5 mm iso, cortico‑limbic
LIVE · CA1 @ 30kHz
● REC
SUBJ 017 · SESSION 42
REPLAY +214ms
CA1-L · TARGET
01ARCHITECTURE

A four-phase closed loop across the memory lifecycle.

The system unifies four phases — encode, consolidate, retrieve, write — under a single hippocampal index layer. Each phase exposes reading (decode) and writing (stim) primitives at its native timescale. Unlike prior memory BCIs that target a single mechanism, This system operates simultaneously across millisecond ripples, hour-long tagging windows, and multi-day cortical integration.

PHASE · 01
Encode
θ–γ PAC · PE
1A · DECODER
Prediction-error monitor
Hierarchical cortical PE signal ≥ θnovel marks encoding-worthy moments.
read · 4 ms
1B · DECODER
Theta–gamma PAC tracker
Modulation index on CA1 LFP; gates tagging eligibility.
read · 5 ms
1C · CONTROLLER
Synaptic tagging scheduler
Schedules neuromod stim inside the 30–120 min tag window.
plan · 10 Hz
1D · STIM
VTA/LC paired bursts
Phasic DA/NE surrogate via patterned microstim; promotes PRP capture.
write · µs
TIMESCALE
100 ms → 2 hr
Ripple to tagging window
PHASE · 02
Consolidate
150–250 Hz SWR
2A · DECODER
SWR detector
Ripple-band power × duration, validated against offline oracle.
read · 8 ms
2B · DECODER
Content classifier
LFADS latent factors → memory id from per-subject library.
read · 12 ms
2C · SLEEP
SO–spindle phase tracker
Locks interventions to NREM up-state for optimal capture.
plan · 1 Hz
2D · STIM
Targeted replay boost
Single-pulse CA1 µstim on target-matched ripples only.
write · SWR-locked
2E · CUE
TMR auditory / olfactory
Learning-paired cues during N3 bias replay content.
write · N3 only
TIMESCALE
Minutes → Nights
Systems integration
PHASE · 03
Retrieve
HG 70–150 Hz
3A · DECODER
Retrieval-attempt detector
PFC activation pattern + hippocampal θ onset flag a search.
read · 15 ms
3B · DECODER
Cortical reinstatement monitor
High-gamma pattern similarity to stored engram template.
read · 20 ms
3C · STIM
CA3 index reactivation
Patterned 20–50 µA µstim matching sparse index code.
write · graded
3D · CONTROLLER
Confidence estimator
Cross-checks reinstatement; throttles assistance to avoid confabulation.
gate · 50 Hz
TIMESCALE
200 ms → 2 s
Pattern completion
PHASE · 04
Write
ENGRAM SYNTH
4A · SPEC
Memory descriptor language
Content + associative map + schema compatibility score.
input · offline
4B · GEN
Manifold-constrained encoder
Projects content onto subject's intrinsic hippocampal manifold.
plan · GPU
4C · STIM
Seed-pattern injection
20–30% of engram into CA3; autoassociator completes the rest.
write · burst
4D · STIM
Inhibitory co-sculpting
VIP+ disinhibition; SST+ caps engram size; PV+ tunes timing.
write · paired
4E · VERIFY
Retrieval probe + fidelity score
Read-back via cue-driven reinstatement; reject-on-drift.
read · 24 hr
TIMESCALE
2 hr → 7 d
Schema-primed path
READ · decoder / sensor WRITE · stim / cue CONTROL · scheduler / gate Fig. 01 — System architecture, all phases
02CORE PRINCIPLE

The sparse index.

The system does not attempt to read or write full cortical memory traces. Instead it operates on the hippocampal index — a sparse ~1,024-dim pointer whose reactivation reinstates distributed cortical patterns. This reduces decoder complexity by three orders of magnitude and makes stim precision tractable with current electrode densities.

FIG. 02 · INDEX SPARSITY · 32 × 32 POINTER k = 48 / 1024 ACTIVE
MEMORY ID · 0x4A19B3E7 DG-CA3 PROJECTION θ-lock 7.1 Hz
COMPRESSION
~104×
distributed cortical trace → hippocampal pointer
PATTERN COMPLETION
20–30%
seed sufficient for CA3 autoassociative convergence
SCHEMA SPEEDUP
48 hr
vs. ~3 weeks for schema-absent consolidation
TWEAKS×