Signal Processing for Functional Brain Imaging: ICA Lab Exercise - PowerPoint PPT Presentation

Signal Processing for Functional Brain Imaging: ICA Lab Exercise Dimitri Van De Ville Medical Image Processing Lab, EPFL/UniGE dimitri.vandeville@epfl.ch April 25, 2013

Lab exercise n Fusion ICA Toolbox [Vince Calhoun and colleagues] http://mialab.mrn.org/software/fit/docs/v2.0a_FIT_Manual.pdf n n Download and install the toolbox and data from the course’s website n http://miplab.epfl.ch/teaching/micro-513/ n Add path of toolbox n use the “set path” GUI, or, alternatively: n addpath(genpath(‘/path/to/toolbox’)); n Make new directory n ! mkdir my_analysis n cd my_analysis n Launch toolbox n fusion 2

Symmetric fusion n Different features “at same level” in decomposition n Joint ICA (blind) feature 1 feature 2 feature 1 feature 2 controls Common Joint independent = x Data (X) mixing patients components (S) matrix n Parallel ICA (semi-blind) feature 1 feature 1 controls mixing = x Data (X) ICs (S1) patients matrix 1 feature 2 maximize feature 2 controls correlation mixing = x Data (X) ICs (S2) patients matrix 2 3

Joint ICA 4

Dataset #1: fMRI + EEG ERP n Combine (non-simultaneously acquired) EEG & fMRI n Auditory oddball experiment n Data n For each subject n fMRI feature = peak of “target”-locked fMRI map n EEG feature = electrode Cz of “target”-locked EEG signal [Calhoun et al., 2006] 5

Joint ICA: Input n Group average of fMRI peak map & ERP [Calhoun et al., 2006] 6

Dataset #1: fMRI + EEG ERP n Setup analysis n Joint ICA n One group, two features (fMRI & EEG) n Do not use “file selection window” for data selection, but use pattern at root data directory n FMRI beta maps & EEG ERP of all subjects are in the subdirectory erp_fmri n Run analysis n Visualize n Also try utils: histograms for fMRI & EEG features 7

Practical n After launching “fusion”, select “joint ICA” n Clicking on “Setup Analysis”, a window will open to select the directory where all the analysis information will be stored n Set the initial parameters 8

Practical n Select the data in setup analysis window n One group, two features (fMRI & EEG) n Do not use “file selection window” for data selection but use pattern at root data directory n Enter the file patterns for both features n Select the data directory. FMRI beta maps & EEG ERP of all subjects are in the subdirectory erp_fmri n Run Analysis 9

Practical n Click on “Display” button n Create EPR-FMRI movie n In “Utilities” menu in Display GUI window n Create Histogram for fMRI & EEG features n Select “Histogram plot” from Joint ICA Toolbox window 10

[Calhoun et al., 2006]

Components with ERP load [Calhoun et al., 2006] 12

Maps at specific ERP timepoints N1 - primary auditory cortex N2 - sensory integration, secondary aud. cortex P3a - frontal and parietal lobes 13 [Calhoun et al., 2006]

ERPs at specific positions in the brain 14 [Calhoun et al., 2006]