README.md

Latent Predictive Learning

This repository contains code for reproducing results reported in our preprint on LPL, a framework for biologically plausible self-supervised learning.

Erratum (updated Jan 2024): Despite careful checking, some errors and typos have made it into the published manuscript. We collect these errors here.

Setup

The deep learning simulations are based on the pytorch lightning framework. We've provided a requirements file to help you install everything you need by just running:

pip install -r requirements.txt

We recommend that you install these into a separate project-specific virtual environment.

For the spiking simulations, you'll need to install Auryn.

Usage

To train a deep net with layer-local LPL, simply run

python lpl_main.py

in the virtual environment you just created. Several useful command-line arguments are provided in lpl_main.py and models/modules.py. A few are listed below to assist you in playing around with the code on your own:

• --train_with_supervision trains the same network with supervision.
• --use_negative_samples trains the network with a cosine-distance-based contrastive loss. Note: this needs to be combined with setting the decorrelation loss coefficient to 0, and enabling the additional projection MLP.
• --train_end_to_end is a flag for training the network with backpropagation to optimize the specified loss (lpl, supervised or neg. samples) at the output layer only.
• --no_pooling optimizes the specified loss on the unpooled feature maps.
• --use_projector_mlp adds additional dense projection heads at every layer in the network where the loss is optimized.
• --pull_coeff, --push_coeff, and --decorr_coeff are the different loss coefficients. Default values are 1.0, 1.0, and 10.0 respectively.
• --dataset specifies the dataset to be used. The Shapes3D dataset needs a separate preprocessing step to make the required sequence of images (detailed in notebooks/E5 - 3D shapes.ipynb).
• --gpus is an integer that specifies the number of GPUs to use. If you have multiple GPUs, you can use this to speed up training or support larger datasets/batches by setting it to a number greater than 1, for example --gpus 2 to use 2 GPUs.

By default, the code trains a VGG-11 network on the CIFAR-10 dataset with LPL. The default hyperparameters are the same as those used in the paper. The code will automatically download the dataset if it is not already present in the ~/data/datasets/ directory. Model performance and other metrics are logged under ~/data/lpl/$DATASET/, where $DATASET is the name of the dataset used. You can monitor training progress by running tensorboard --logdir ~/data/lpl/$DATASET/ in a separate terminal window.

Note on network architectures

Only a VGG-11 architecture has been extensively tested, but the framework easily extends to other architectures. You can simply configure another encoder in models/encoders.py, and add it to models/network.py. In principle, everything should work with residual architectures (provided as an option) as well, but layer-local learning in this case is not well-defined because of the non-plastic skip connections.

Analysis and reproduction of figures

Jupyter notebooks under notebooks contain instructions on extracting and visualizing several metrics for the quality of learned representations. Also provided in the notebooks is the code for generating figures from the paper.

Spiking network code

You find the spiking network code and instructions for reproducing the corresponding results under spiking_simulations/.

Citation

@article{halvagal_combination_2023,
    title = {The combination of {Hebbian} and predictive plasticity learns invariant object representations in deep sensory networks},
    author = {Halvagal, Manu Srinath and Zenke, Friedemann},
    year = {2023},
    journal = {Nature Neuroscience},
    volume = {26},
    number = {11},
    pages = {1906--1915},
    issn = {1546-1726},
    url = {https://www.nature.com/articles/s41593-023-01460-y},
    doi = {10.1038/s41593-023-01460-y},
}