15.02.2014 Views

Integrating MEG, EEG and fMRI data

Integrating MEG, EEG and fMRI data

Integrating MEG, EEG and fMRI data

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

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

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!