Multi-Plasticity Networks for Reinforcement Learning

Trains MPN (Multi-Plasticity Network), LSTM, and RNN agents on cognitive neuroscience tasks using A2C. MPNs combine long-term weight learning via backpropagation with short-term Hebbian plasticity as a recurrent memory layer.

Architecture

The actor-critic network uses a recurrent core selected by --model-type:

Observation → core (MPN / LSTM / RNN)
                → Linear(hidden_dim, 64) + ReLU
                → actor:  Linear(64, output_dim) → Softmax
                → critic: Linear(64, 1)

MPN update rules:

Hebbian plasticity:

M_t = λ·M_{t-1} + η·h_t·x_t^T

Multiplicative modulation:

h = activation(b + W·(M + 1)·x)

• M: synaptic modulation matrix (recurrent state)
• W: long-term weights (learned via backprop)
• η (eta): Hebbian learning rate
• λ (lambda): decay factor for M

Installation

git clone <repository-url>
cd mpn-rl
./setup.sh
source .venv/bin/activate

Quick Start

Train on NeuroGym environments

# LSTM baseline on GoNogo
python main_a2c.py train-neurogym --env-name GoNogo-v0 --model-type lstm

# MPN agent on DMS
python main_a2c.py train-neurogym --env-name DelayMatchSample-v0 --model-type mpn

# Multi-layer MPN with custom hyperparameters
python main_a2c.py train-neurogym \
    --env-name GoNogo-v0 \
    --model-type mpn \
    --hidden-dim 128 \
    --num-layers 2 \
    --learning-rate 1e-4 \
    --total-frames 500000

Train on custom environments

# IntervalTiming1D, IntervalDisc1D, DelayMatchSample
python main_a2c.py train-custom --env-name IntervalTiming1D --model-type mpn
python main_a2c.py train-custom --env-name DelayMatchSample --num-layers 2

Evaluate and render

python main_a2c.py eval --experiment-name <name> --num-eval-episodes 20
python main_a2c.py render --experiment-name <name> --output render.png

Query results

# Summary of all experiments
python query_experiments.py list

# Best runs for a given environment
python query_experiments.py best --env GoNogo-v0

# Compare model types
python query_experiments.py compare --model-type mpn

Key Parameters

Parameter	Default	Description
--model-type	lstm	lstm, rnn, mpn, mpn-frozen
--hidden-dim	128	Hidden layer size
--num-layers	1	Number of recurrent layers
--total-frames	500000	Training budget (frames)
--learning-rate	1e-4	Adam learning rate
--gamma	0.98	Discount factor
--entropy-coef	0.01	Entropy regularization
--eta-init	0.01	MPN Hebbian learning rate
--lambda-init	0.99	MPN decay factor

Key Files

• main_a2c.py: CLI entry point — train, eval, render
• src/mpn_rl/nn/mpn.py: MPN layer with Hebbian plasticity
• custom_envs.py: Custom RL environments (IntervalTiming1D, IntervalDisc1D, DelayMatchSample)
• src/mpn_rl/temporal_order_env.py: TemporalOrder environment family
• src/mpn_rl/experiment.py: ExperimentManager, checkpointing, JSONL metrics
• src/mpn_rl/oracle_agents.py: Oracle baselines for all supported environments
• query_experiments.py: Live DuckDB queries over experiment output files
• plots/: Plotting scripts for rewards, sweeps, trial lengths

Experiment Directory Structure

experiments/{experiment-name}/
├── config.json           # Hyperparameters
├── metrics.jsonl         # One JSON line per eval step (live-queryable)
├── checkpoints/
│   ├── best_model.pt
│   └── final_model.pt
└── render.png            # Episode render (if generated)

Running Jobs on HTCondor

The condor/ directory contains submit files (.job), shell scripts (.sh), and argument files (_args.txt) for running sweeps on the cluster.

Submit a sweep

# Submit a job
condor_submit condor/jobs/train_neurogym.job

# Check status
condor_q

# Monitor output
tail -f condor/logs/train_0.out

Create a new sweep

1. Add an args file to condor/args/ (one set of arguments per line)
2. Add a shell script to condor/scripts/ (activate .venv, call main_a2c.py)
3. Add a .job file to condor/jobs/ pointing at the script and args file

Resource guidelines

• CPU training: request_cpus = 1, request_memory = 4GB
• GPU training: request_cpus = 2, request_gpus = 1, request_memory = 8GB

Managing jobs

condor_q              # job status
condor_q -hold        # check held jobs
condor_release <id>   # release a held job
condor_rm <username>  # remove all your jobs