<div dir="ltr"><div><div><div><div><div><div><div>Dear filedtripper,<br></div><br></div>That was quite a while I follow your activity.<br></div>But now I am back to active analysis and stucked...<br></div><div>I'd like to calculate ITC/PLF in a source space similar to described <ul style="display:inline" class="" id=""><li><a href="http://www.sciencedirect.com/science/article/pii/S1053811908004989#" class="" id="authname_N54b41c10N5bf977c0">T. Bardouille</a><sup>, </sup>,<a href="http://www.sciencedirect.com/science/article/pii/S1053811908004989#" class="" id="authname_N54b41c10N5bf97850">B. Ross, 2008 paper.</a></li></ul></div><div><br></div><div>I have 40Hz-auditory steady state response from 306 neuromag system. I figured out how to calculate ITC on sensor space from complex FFT coeficients obtained by ft_freqanalysis. <br><br>As a next step I need to do this in source space. My vision that I can use complex FFT coeficients, obtained in sensor space but "project" them to source space by multiplying with weigted matrix. In the above mentioned paper they applied the LCMV beamformer to determine the weighting function, <em>w</em><sub><em>jm</em></sub>,
that estimates the source activity across the steady-state time
interval in the frequency band of interest. How can I do this?<br><br></div><div>I tried to do it using ft_sourceanalysis but get lost. If I specified lcmv method and feed it with average timelocked data as in the example<br>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg
= [];</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.method
= </font></font></font><font color="#a020f0"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">'lcmv'</font></font></font><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">;</font></font></font></p><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.grid
= grid;</font></font></font>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.vol
= test_vol;</font></font></font></p><p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.lcmv.keepfilter
= </font></font></font><font color="#a020f0"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">'yes'</font></font></font><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">;</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2"></font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">sourceAll
= ft_sourceanalysis(cfg, test_data_LEar_avg);</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><br></p><p style="margin-bottom:0in;line-height:100%">or for a frequency decomposed data using disc</p><p style="margin-bottom:0in;line-height:100%">
</p><p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg
= [];</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.method
= </font></font></font><font color="#a020f0"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">'dics'</font></font></font><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">;</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.frequency
= 40;</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.grid
= grid;</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.vol
= test_vol;</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.dics.projectnoise
= </font></font></font><font color="#a020f0"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">'yes'</font></font></font><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">;</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.dics.lambda
= </font></font></font><font color="#a020f0"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">'5%'</font></font></font><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">;</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.dics.keepfilter
= </font></font></font><font color="#a020f0"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">'yes'</font></font></font><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">;</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">cfg.dics.realfilter
= </font></font></font><font color="#a020f0"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">'yes'</font></font></font><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">;</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%"><font color="#000000"><font face="lucidatypewriter, serif"><font style="font-size:10pt" size="2">sourceAll
= ft_sourceanalysis(cfg, test_freq_LEar);</font></font></font></p>
<p style="margin-bottom:0in;line-height:100%">As output I get in the sourceAll.avg.filter some weigth matrix (although I am not fully sure if that is what I need). Unfortunately, I did not find the way (filtrip function) to apply this filter/weigths to itc or complex FFT coeficients. Should I write my our code for this? Which way is better: multiply it to itc or first to complex fft and than calculate itc? Which matrix to use (from disc or lcmv)? Is my way of thinking makes sense or am I completely lost?<br>
</p>
<p style="margin-bottom:0in;line-height:100%">
</p>
</div><div>I would be really thankfull for any help. <br></div><div><br></div>Best Regards,<br></div>Olga Sysoeva, PhD,<br></div>Senior Researcher,<br></div>MEG-center, Moscow.<br></div>