Examining the Impact of fMRI Preprocessing Steps on Machine Learning-Based Classification of Autism Spectrum Disorder
Bibliographic record
Abstract
The use of functional magnetic resonance imaging (fMRI) data in machine learning (ML)-based classification of autism spectrum disorder (ASD) has been a topic of increasing research interest in past years due to the noninvasiveness of the fMRI technique and its potential for providing valuable biomarkers. However, there are still controversies surrounding some fMRI data preprocessing steps, such as bandpass filtering and global signal regression (GSR). It still needs to be determined whether or how these preprocessing steps impact the classification accuracy of ML algorithms. This paper uses fMRI signals from the ABIDE-I dataset to train a long short-term memory (LSTM) network to classify subjects into ASD or healthy controls (HC). We considered 18 preprocessing pipelines comprising all combinations of with and without filtering, with and without global signal regression, and three different segment lengths of 1 min, 2 min, and 3 min. The best model was obtained when using a segment length of 2 min. Our results suggest that not filtering produces significantly higher classification accuracies than filtering, whereas there were no significant differences in classification accuracies when removing or not the global signal.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".