Spatially aggregated multiclass pattern classification in functional MRI using optimally selected functional brain areas.
Spatially aggregated multiclass pattern classification in functional MRI using optimally selected functional brain areas.
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DOI：
10.1016/j.mri.2012.07.010
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发表时间：
2013-02
影响因子：
2.5
通讯作者：
Posse, Stefan
中科院分区：
文献类型：
--
作者：
Zheng, Weili;Ackley, Elena S.;Martinez-Ramon, Manel;Posse, Stefan
In previous works, boosting aggregation of classifier outputs from discrete brain areas has been demonstrated to reduce dimensionality, and improve the robustness and accuracy of fMRI classification. However, dimensionality reduction and classification of mixed activation patterns of multiple classes remain challenging. In the present study, the goals were (a) to reduce dimensionality by combining feature reduction at the voxel level and backward elimination of optimally aggregated classifiers at the region level, (b) to compare region selection for spatially aggregated classification using boosting and partial least squares regression methods and (c) to resolve mixed activation patterns using probabilistic prediction of individual tasks. Brain activation maps from interleaved visual, motor, auditory and cognitive tasks were segmented into 144 functional regions. Feature selection reduced the number of feature voxels by more than 50%, leaving 95 regions. The two aggregation approaches further reduced the number of regions to 30, resulting in more than 75% reduction of classification time and misclassification rates of less than 3%. Boosting and partial least squares (PLS) were compared to select the most discriminative and the most task correlated regions, respectively. Successful task prediction in mixed activation patterns was feasible within the first block of task activation in real time fMRI experiments. This methodology is suitable for sparsifying activation patterns in real-time fMRI and for neurofeedback from distributed networks of brain activation.
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