Generalized sparse classifiers for decoding cognitive states in fMRI

  • Authors:
  • Bernard Ng;Arash Vahdat;Ghassan Hamarneh;Rafeef Abugharbieh

  • Affiliations:
  • Biomedical Signal and Image Computing Lab, The University of British Columbia;Vision and Media Lab, Simon Fraser University;Medical Image Analysis Lab, Simon Fraser University;Biomedical Signal and Image Computing Lab, The University of British Columbia

  • Venue:
  • MLMI'10 Proceedings of the First international conference on Machine learning in medical imaging
  • Year:
  • 2010

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Abstract

The high dimensionality of functional magnetic resonance imaging (fMRI) data presents major challenges to fMRI pattern classification. Directly applying standard classifiers often results in overfitting, which limits the generalizability of the results. In this paper, we propose a new group of classifiers, "Generalized Sparse Classifiers" (GSC), to alleviate this overfitting problem. GSC draws upon the recognition that numerous standard classifiers can be reformulated under a regression framework, which enables state-of-the-art regularization techniques, e.g. elastic net, to be directly employed. Building on this regularized regression framework, we exploit an extension of elastic net that permits general properties, such as spatial smoothness, to be integrated. GSC thus facilitates simultaneous sparse feature selection and classification, while providing greater flexibility in the choice of penalties. We validate on real fMRI data and demonstrate how explicitly modeling spatial correlations inherent in brain activity using GSC can provide superior predictive performance and interpretability over standard classifiers.