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

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n Fusion ICA Toolbox [Vince Calhoun and colleagues]

n

http://mialab.mrn.org/software/fit/docs/v2.0a_FIT_Manual.pdf

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

Symmetric fusion

n Different features “at same level” in decomposition

n Joint ICA (blind) n Parallel ICA (semi-blind) 3

Data (X)

feature 1 controls

=

Common mixing matrix

x

Joint independent components (S)

feature 2 patients feature 1 feature 2

Data (X)

feature 1 controls

=

mixing matrix 1

x

ICs (S1)

patients feature 1

Data (X)

controls

=

mixing matrix 2

x

ICs (S2)

feature 2 patients feature 2 maximize correlation

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Joint ICA

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

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[Calhoun et al., 2006]

Joint ICA: Input

n Group average of fMRI peak map & ERP

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[Calhoun et al., 2006]

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

• pen to select the

directory where all the analysis information will be stored

n Set the initial

parameters

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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

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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

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[Calhoun et al., 2006]

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Components with ERP load

[Calhoun et al., 2006]

Maps at specific ERP timepoints

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[Calhoun et al., 2006] N1 - primary auditory cortex N2 - sensory integration, secondary aud. cortex P3a - frontal and parietal lobes

ERPs at specific positions in the brain

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[Calhoun et al., 2006]