Source localization MfD 2010, 17th Feb 2010 Diana Omigie in addition to Stjepana Kovac Sour

Source localization MfD 2010, 17th Feb 2010 Diana Omigie in addition to Stjepana Kovac Sour www.phwiki.com

Source localization MfD 2010, 17th Feb 2010 Diana Omigie in addition to Stjepana Kovac Sour

Sagon, Erica, Online Style Editor and Fashion Reporter has reference to this Academic Journal, PHwiki organized this Journal Source localization MfD 2010, 17th Feb 2010 Diana Omigie in addition to Stjepana Kovac Source localization: I Aim / Application II Theory a) What is recorded (EEG / MEG) b) Forward problem Forward solutions c) Inverse problem Inverse solutions d) Inverse solutions: discrete vs. distributed III The buttons in SPM I Aim To find a focus of brain activity by analysing the electrical activity recorded from surface electrodes (EEG) or SQUID (Superconductive Quantum Interference Device; MEG)

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I Application: – focal epilepsy: spikes seizures – evoked potentials: auditory evoked potentials somatosensory evoked potentials cognitive event related potentials – IIa What is recorded Lopez daSilva, 2004 EPSP – Layer IV IIb Forward problem Forward solution How to model the surfaces i.e. the area between recording electrode in addition to cortical generator Plummer, 2008 Realistic shape – (BEM isotropic, FEM anisotropic) Skin, CSF, skull, brain

IIc Inverse problem Inverse solutions Discrete: Equivalent current dipole Distributed (differ in side constraint): Minimum norm (Halmalainen & Ilmoniemi 1984) LORETA (Pascual-Marqui, 1994) MSP – multiple sparse priors (Friston, 2008) IIc Inverse problem Inverse solutions Two aspects of source analysis are original in SPM: Based on Bayesian as long as malism: generic inversion it can incorporate in addition to estimate the relevance of multiple constraints (data driven relevance estimation – Baysian model comparison) The subjects specific anatomy incorporated in the generative model of the data SPM source analysis

III The buttons in SPM : Graphical user interface as long as 3D source localisation III EEG/MEG imaging pipeline 0) Load the file Source space modeling Data co-registration Forward computation Inverse reconstruction Summarizing the results of the inverse reconstruction as an image 0) Load the file

1) Source space modeling MRI – individual head meshes (boundaries of different head compartments) based on the subject’s structural scan Template – SPM’s template head model based on the MNI brain 1) Source space modeling Select mesh size: – coarse normal fine 2) Data co-registration Fiducials – l in addition to mark based coregistration Surface matching

2) Data co-registration Methods to co-register “select” from default locations “type” MNI coordinates directory “click” manually each fiducial point from MRI images 3) Forward computation Recommendation: Single shell as long as MEG BEM as long as EEG 3) Forward computation

4) Inverse reconstruction Imaging VB-ECD Beam as long as ming 4) Inverse reconstruction Default – click “St in addition to ard”: “MSP” method will be used. MSP : Multiple Sparse Priors (Friston et al. 2008a) Alternatives: GS (greedy search: default): iteratively add constraints (priors) ARD (automatic relevance determination): iteratively remove irrelevant constraints COH (coherence): LORETA-like smooth prior 4) Inverse reconstruction TIME Time course of the region with maximal activity SPACE Maximal intensity projection (MIP)

5) Summarizing the results of inverse reconstruction as an image Timewindow of interest (ms peri-stimulus time) Frequency b in addition to of interest (default 0) Evoked/ induced inversion applied either to each trial (induced) in addition to then averaged or inversion applied to the averaged trials (evoked) 5) Summarizing the results of inverse reconstruction as an image 3D NIfTI images allow GLM based statistical analysis (R in addition to om field theory) Sources indicated under figures – Stavroula Kousta / Martin Chadwick (2007, MfD) – Maro Machizawa / Himn Sabir (2008, MfD) – SPM 8 manual BESA tutorials (http://www.besa.de), M. Scherg

Sagon, Erica Arizona Republic - Online Online Style Editor and Fashion Reporter www.phwiki.com

Sagon, Erica Online Style Editor and Fashion Reporter

Sagon, Erica is from United States and they belong to Arizona Republic – Online and they are from  Phoenix, United States got related to this Particular Journal. and Sagon, Erica deal with the subjects like Fashion and Wearing Apparel; Fashion Industry

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