Integrating MEG, EEG and fMRI data
Integrating MEG, EEG and fMRI data
Integrating MEG, EEG and fMRI data
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How can we integrate <strong>MEG</strong>, <strong>EEG</strong>, <strong>and</strong> <strong>fMRI</strong> ?<br />
d. Use of distributed sources <strong>and</strong> regularization of<br />
Linear inverse Estimation (LE)<br />
• since the number of dipole components (5,000-10,000) is<br />
much larger than the number of measurements (150-500),<br />
we must minimize the following expression (cost<br />
function):<br />
⎜⎜Ax - b⎜⎜ + λ 2 ⎜⎜Cx ⎜⎜<br />
where λ is the so-called regularization parameter <strong>and</strong> C is<br />
simply a weight matrix that depends on the head model.<br />
• By appropriately shaping C we can take into account the<br />
possible constraints used in various LE analysis methods<br />
(Minimum Norm, SLORETA, etc.), but also the <strong>fMRI</strong><br />
constraints