Bidimensional ensemble empirical mode decomposition of functional biomedical images taken during a contour integration task

• FMRI data from a contour integration task are analyzed with empirical mode decomposition.
• Extracted textures show high discriminative power with a SVM classifier.
• Extracted intrinsic mode functions represent spatially localized activity distributions.
• Distributed activity in bilateral inferior temporal and superior occipital lobe is maximally predictive for the stimulus condition.
• Furthermore, results distinctly show the participation of frontal brain areas in contour integration.

In cognitive neuroscience, extracting characteristic textures and features from functional imaging modalities which could be useful in identifying particular cognitive states across different conditions is still an important field of study. This paper explores the potential of two-dimensional ensemble empirical mode decomposition (2DEEMD) to extract such textures, so-called bidimensional intrinsic mode functions (BIMFs), of functional biomedical images, especially functional magnetic resonance images (fMRI) taken while performing a contour integration task. To identify most informative textures, i.e. BIMFs, a support vector machine (SVM) as well as a random forest (RF) classifier is trained for two different stimulus/response conditions. Classification performance is used to estimate the discriminative power of extracted BIMFs. The latter are then analyzed according to their spatial distribution of brain activations related with contour integration. Results distinctly show the participation of frontal brain areas in contour integration. Employing features generated from textures represented by BIMFs exhibit superior classification performance when compared with a canonical general linear model (GLM) analysis employing statistical parametric mapping (SPM).

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