Semantic Decoding

This repository contains code used in the paper "Semantic reconstruction of continuous language from non-invasive brain recordings" by Jerry Tang, Amanda LeBel, Shailee Jain, and Alexander G. Huth.

Usage

1. Download language model data and extract contents into new data_lm/ directory.

2. Download training data and extract contents into new data_train/ directory. Stimulus data for train_stimulus/ and response data for train_response/[SUBJECT_ID] can be downloaded from OpenNeuro.

3. Download test data and extract contents into new data_test/ directory. Stimulus data for test_stimulus/[EXPERIMENT] and response data for test_response/[SUBJECT_ID] can be downloaded from OpenNeuro.

4. Estimate the encoding model. The encoding model predicts brain responses from contextual features of the stimulus extracted using GPT. The --gpt parameter determines the GPT checkpoint used. Use --gpt imagined when estimating models for imagined speech data, as this will extract features using a GPT checkpoint that was not trained on the imagined speech stories. Use --gpt perceived when estimating models for other data. The encoding model will be saved in MODEL_DIR/[SUBJECT_ID]. Alternatively, download pre-fit encoding models.

python3 decoding/train_EM.py --subject [SUBJECT_ID] --gpt perceived

5. Estimate the word rate model. The word rate model predicts word times from brain responses. Two word rate models will be saved in MODEL_DIR/[SUBJECT_ID]. The word_rate_model_speech model uses brain responses in speech regions, and should be used when decoding imagined speech and perceived movie data. The word_rate_model_auditory model uses brain responses in auditory cortex, and should be used when decoding perceived speech data. Alternatively, download pre-fit word rate models.

python3 decoding/train_WR.py --subject [SUBJECT_ID]

6. Test the decoder on brain responses not used in model estimation. The decoder predictions will be saved in RESULTS_DIR/[SUBJECT_ID]/[EXPERIMENT_NAME].

python3 decoding/run_decoder.py --subject [SUBJECT_ID] --experiment [EXPERIMENT_NAME] --task [TASK_NAME]

7. Evaluate the decoder predictions against reference transcripts. The evaluation results will be saved in SCORE_DIR/[SUBJECT_ID]/[EXPERIMENT_NAME].

python3 decoding/evaluate_predictions.py --subject [SUBJECT_ID] --experiment [EXPERIMENT_NAME] --task [TASK_NAME]