Brain connectivity repository

This repository contains code to run machine learning experiments with functional connectivity matrices, including training scripts with nested cross validation.

You can read my 2022 Master thesis from MMF UK in Prague on "Utilization of brain connectivity in classification and regression tasks in brain data" here.

Contents

• brain-connectivity/: Package with code powering the experiments.
  • README.md: Info about the package.
• data-exploration/
  • timeseries.ipynb: Preprocessing raw data for experiments. Exploration of raw timeseries.
  • functional-connectivity.ipynb: Visual exploration of functional connectivity matrices.
• data/: All data goes here. FC matrices are cached after first computation.
  • timeseries.pickle: Pickled numpy array of shape [num_subjects, num_brain_regions, num_time_points].
  • subjects.csv: CSV with modeling targets that presumes header and index. Targets in header are {"target", "age", "sex"}.
• experiments/
  • run_experiment.py: Script for deep learning experiments.
  • run_ml_experiment.py: Script for standard machine learning experiments.
  • <model>_config.py: Hyperparameter configuration for <model>.

Data

fMRI data are private and therefore not provided. Instead, the data folder contains dummy time series and targets.

Get started

Clone the repository.

git clone https://github.com/janarez/brain-connectivity.git

Since installing PyTorch and PyTorch Geometric using the correct wheels from setup.py is tricky, the whole repository has its own requirements.txt file. Install requirements by running:

cd brain-connectivity
pip install -r requirements.txt

You might need to adjust the CUDA version for your machine (or don't use it).

Then install the brain-connectivity package via pip from its top level directory (where setup.py is located):

cd brain-connectivity
pip install -e .

Surrogates

The brain-connectivity package supports creating surrogate time series using the nolitsa repository. It, however, needs to be patched. If you want to use this functionality run the following steps:

cd ..
git clone https://github.com/manu-mannattil/nolitsa.git
cd nolitsa
git checkout 40bef
git apply ../nolitsa.patch
pip install -e .

Developing

The brain_connectivity package uses isort, black and flake8 for consistent formatting (see .vscode/settings.json for used settings). For development purposes you might want to include these dependencies during package install by:

pip install -e .[dev]

Run experiments

For standard machine learning experiments run the run_ml_experiment.py script. For PyTorch deep learning models run the run_experiment.py script.

To see the required and optional script arguments use the --help flag.

Each model's hyperparameter configuration is in its config file (e.g., gin_config.py). The hyperparameter names correspond to initialization arguments of either model, trainer or dataset class. You can check the relevant class for description of each hyperparameter.

If you want to replicate the experiments from the diploma thesis read thesis_experiments.md. The frozen requirements might come in handy too.

Notebooks

The data-exploration folder contains two notebooks. They are saved with outputs, so you can check what functional connectivity data look like.

The timeseries.ipynb notebook in the first part loads raw data and prepares them for experiments. This can only be run with the raw data files. The second part visualizes the time series and can be run independently of the first part.

The functional-connectivity.ipynb notebook explores functional connectivity matrices. You can create the matrices using connectivity functions from the brain_connectivity package.