AUTHOR=Kampel Nikolas , Abdellatif Farah , Shah N. Jon , Neuner Irene , Dammers Jürgen 

TITLE=Contrastive learning for neural fingerprinting from limited neuroimaging data

JOURNAL=Frontiers in Nuclear Medicine

VOLUME=Volume 4 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/nuclear-medicine/articles/10.3389/fnume.2024.1332747

DOI=10.3389/fnume.2024.1332747

ISSN=2673-8880

ABSTRACT=Neural fingerprinting is a technique used to identify individuals based on their unique brain activity patterns. While deep learning techniques have been demonstrated to outperform traditional correlation-based methods, they often require retraining to accommodate new subjects. Furthermore, the limited availability of samples in neuroscience research can impede the quick adoption of deep learning methods, presenting a challenge for their broader application in neural fingerprinting. This study addresses these challenges by using contrastive learning to eliminate the need for retraining with new subjects and developing a data augmentation methodology to enhance model robustness in limited sample size conditions. 
We utilized the LEMON dataset, comprising 3 Tesla MRI and resting-state fMRI scans from 138 subjects, to compute functional connectivity as a baseline for fingerprinting performance based on correlation metrics. We adapted a recent deep learning model by incorporating data augmentation with short random temporal segments for training and reformulated the fingerprinting task as a contrastive problem, comparing the efficacy of contrastive triplet loss against conventional cross-entropy loss.
The results of this study confirm that deep learning methods can significantly improve fingerprinting performance over correlation-based methods, achieving an accuracy of about 98% in identifying a single subject out of 138 subjects utilizing 39 different functional connectivity profiles. The contrastive method also showed added value in the "leave subject out" scenario, aligning with the flexibility of correlation-based similarity methods, and demonstrated robustness regardless of the data size.