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Measuring Activation and Causality using multiple Prior Information Pedro A. Valdés-Sosa Cuban Neuroscience Center
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Mapping
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Brain Maps
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Multimodal T1-Nissl-cryotomy-PET-myelin stain
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Localization versus Connectivity Hiparcus ( II BC) Jackson US air Traffic Luria
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Localization versus Connection AnatomicalPhysiological Localization Morphometry: Voxel based Region based Cortical thickness Activation: EEEG/MEG fMRI Connection Anatomical Connectivity Diffusion Weighted Functional Connectivity Effective Connectivity
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Brain Tomographies Physical Model of some brain characteristic Prediction of measurement Direct Problem Image of some brain characteristic measurement Inverse Problem a Priori Information
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EEG/MEG Forward Problem Primary current j EEG/MEG v
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EEG inverse Problem Bayesian Inference!!
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Methods for Regression Data VARETA LORETA ICA Non Negative Matrix Factorization In fact can be unified or combined
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L0 Norm “Sparsness” AIC, BIC, TIC, RIC “subset selection”“Matching Purusit”“Dipoles”
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L1 Norm “Sparseness” “Lasso”“Basis Pursuit”“FOCUSS” Connection with ICA
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Fast LARS Algorithm (Friedman, Hastie, Tibshirani) Regularization path for diabetes data
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L2 Norm “Minimum Norm” “Ridge”“Frames”“Minimum Norm”
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Simplest EEG inverse Problem Bayesian Inference!!
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Multiple Priors SparsenessMinimal Norm Non smoothDipoles=FOCUSSMinimum Norm SmoothVARETALORETA
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Which inverse solution to choose?: let the data decide combining all solutions
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Bayesian Model Averaging For 69 compartments
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Simulations with Bayesian Model Averaging
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BMA during concurrent EEG/fMRI
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Combining Priors Fused Lasso VARETA-LORETA
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Combining penalties (L1,I) (L1,L)
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Between LORETA and VARETA LORETA VARETA Solution Chosen
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Further Combination: Multiple Priors plus (semi) Non Negative Matrix Factorization Non Negative Matrix Factorizations used for data reduction Equivalent to Cluster Analysis
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Multiple Priors plus (semi) Non Negative Matrix Factorization
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Fast Non-negative LARS Algorithm (Morup) Regularization paths for diabetes data
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Results for a Simulation 64 Channels, 1 Patch complex time series BIC Regularization path
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Results of a Simulation
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Localization versus Connection AnatomicalPhysiological Localization Morphometry: Voxel based Region based Cortical thickness Activation: EEEG/MEG fMRI Connection Anatomical Connectivity Diffusion Weighted Functional Connectivity Effective Connectivity
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Effective vs. Functional Connectivity (Karl Friston)
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Statistical Analysis of Causal Modeling "Beyond such discarded fundamentals as 'matter' and 'force' lies still another fetish amidst the inscrutable arcana of modern science, namely, the category of cause and effect.“ Karl Pearson (1911)
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Granger (Non) Causality for TWO time series 1212 1212 Granger Non Causality t t-1 t =1,…,N
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Granger Causality of EEG signals Freiwald et al. (1999) J. Neurosci. Methods. 94:105-119 C3 C4 t t-1
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What happens when you have a LOT of time series? 12…p12…p … t t-1 t =1,…,N Long history: Bressler, Baccala, Kaminski, Eichler, Goebel
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Problems with the Multivariate Autoregressive Model for Brain Manifolds p→∞p→∞ # of parameters likelihood
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Regions of Interest Alemán-Gómez Y. et al. PS0103
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Point influence Measures is the simple test
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38 Spike and Wave
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39 Spike and Wave
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What happens when you have a LOT of time series? 12…p12…p … t t-1 t =1,…,N Long history: Bressler, Baccala, Kaminski, Eichler, Goebel
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a) Teat CG as a Random Field Concept applied to correlation fields by Worsley Usual SPM: RF is the brain New Idea RF is Cartesian product of Brain by Brain = = X
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Granger Causality must be measured on a MANIFOLD
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Influence Measures defined on a Manifold An influence field is a multiple test and all for a given
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Discretization of the Continuos AR Model
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Influence Fields and Bayesian Estimation Influence field likelihood prior
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Influence Fields Outield Infield
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Priors for Influence Fields maximal SMOOTHNESS Valdés-Sosa PA Neuroinformatics (2004) 2:1-12 Valdés-Sosa PA et al. Phil. Trans R. Soc. B (2005) 360: 969-981 Minimum norm I Minimum spatial laplacian L prior
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vs FFA Amigdala Fear Static + Fear Dynamic Neutral Neural basis of emotional expression processing
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Emotional Network (Dipole)
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Cuban Neuroscience Center Concurrent EEG-fMRI recordings Fine time scale
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Cuban Neuroscience Center Concurrent EEG-fMRI ( Rhythm)
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Basis of concurrent EEG/MEG-fMRI analysis-voxel level Trujillo et al. IJBEM (2001) BOLD Vasomotor Feed Forward Signal VFFS Ensemble of Postsynaptic Potentials ePSP net Primary Current Density nPCD EEG/MEG
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EEG/MEG-fMRI-voxel Inverese solution Association BOLD VFF S ePSP nPCD EEG/MEG
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correlationlog BOLD-log j
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First order Autoregressive Model for fMRI and EEG
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Estimated A for fMRI-EEG (f,s) using L1 regularizer
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EEG-fMRI influence Fields Maximal Evidence dipole MN non smooth smooth nonsmooth+smooth dipole+MN
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http://journals.royalsociety.org/content/md5e04y6bgm8 /
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Localization versus Connection AnatomicalPhysiological Localization Morphometry: Voxel based Region based Cortical thickness Activation: EEEG/MEG fMRI Connection Anatomical Connectivity Diffusion Weighted Functional Connectivity Effective Connectivity
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