<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif;font-size:large"><div class="gmail_default"><span style="color:rgb(40,40,40)">Hello All, </span></div><div class="gmail_default"><span style="color:rgb(40,40,40)">Has anyone tried to compare cluster locations between different conditions within the same experimental session?</span><br>
</div><div class="gmail_quote" style="font-family:arial;font-size:small"><div dir="ltr"><div style="font-size:12pt;color:rgb(0,0,0);font-family:'Times New Roman',Times,serif"><div style="font-size:16px"><font face="Segoe UI WPC,Segoe UI,Tahoma,Microsoft Sans Serif,Verdana,sans-serif" color="#282828"><span style="font-size:15px"><font face="arial,helvetica,sans-serif" size="4">We are interested in locating dipoles associated specifically with encoding versus maintenance during a working memory task, and are using EEGLAB to conduct ICA and then PCA to examine dipoles.</font></span></font></div>
<div style="font-size:16px"><font face="Segoe UI WPC,Segoe UI,Tahoma,Microsoft Sans Serif,Verdana,sans-serif" color="#282828"><span style="font-size:15px"><font face="arial,helvetica,sans-serif" size="4"><br></font></span></font></div>
<div style="font-size:16px"><font face="Segoe UI WPC,Segoe UI,Tahoma,Microsoft Sans Serif,Verdana,sans-serif" color="#282828"><span style="font-size:15px"><font face="arial,helvetica,sans-serif" size="4">Our first method did not give us much success--originally, we tried running ICA on the entire dataset (including both encoding and maintenance conditions), and epoched after ICA was run, so that we ended up with separate files for the two conditions, each with the same ICA weights. When we ran STUDIES for each condition separately, we found the resulting clusters were the same between encoding and maintenance conditions, even though we expected differences to exist. <br>
</font></span></font></div><div style="font-size:16px"><font face="Segoe UI WPC,Segoe UI,Tahoma,Microsoft Sans Serif,Verdana,sans-serif" color="#282828"><span style="font-size:15px"><font face="arial,helvetica,sans-serif" size="4"><br>
</font></span></font></div><div style="font-size:16px"><font face="Segoe UI WPC,Segoe UI,Tahoma,Microsoft Sans Serif,Verdana,sans-serif" color="#282828"><span style="font-size:15px"><font face="arial,helvetica,sans-serif" size="4">Because we didn't experience success with this method, we are wondering whether it would be advisable to create two separate files for each participant (from the same session) BEFORE running ICA-- One file would contain EEG data epoched from the first condition (encoding--two seconds per trial), and the second EEG data epoched from the second condition (maintenance--2 seconds per trial). We would then run ICA </font><font face="arial,helvetica,sans-serif" size="4"><strong>separately</strong></font><font face="arial,helvetica,sans-serif" size="4"> for each file and look to see if there were dipoles from the encoding condition ICA that</font><font face="arial,helvetica,sans-serif" size="4"><em> consistently </em></font><font face="arial,helvetica,sans-serif" size="4">were not in the maintenance condition ICA results (and vice versa). We have a priori hypotheses of where maintenance activity would be taking place source-wise as compared to where encoding would be taking place. We are wondering if it is advisable to compare dipoles that result from different ICA weights- even when they are collected from the same session and just seconds apart. If there were unique sources of brain activity (dipoles) would it be possible, from this design, to conclude that the unique dipoles were in fact associated with the different stages of the working memory task (all other factors being held constant)? </font></span></font></div>
<div style="font-size:16px"><font face="Segoe UI WPC,Segoe UI,Tahoma,Microsoft Sans Serif,Verdana,sans-serif" color="#282828"><span style="font-size:15px"><font face="arial,helvetica,sans-serif" size="4"><br></font></span></font></div>
<div style="font-size:16px"><font face="Segoe UI WPC,Segoe UI,Tahoma,Microsoft Sans Serif,Verdana,sans-serif" color="#282828"><span style="font-size:15px"><font face="arial,helvetica,sans-serif" size="4">Thanks for your thoughts on this. We are aware that we need to make sure we have large enough files in order to conduct ICA in the first place.</font></span></font></div>
<p><span style="color:rgb(34,34,34);font-family:arial;font-size:small">Kathleen (Kathy) Van Benthem M.H.S., B.Sc.O.T </span><br></p><div><span style="color:rgb(34,34,34);font-family:arial;font-size:small">Carleton University, Institute of Cognitive Science, </span><span style="color:rgb(34,34,34);font-family:arial;font-size:small">Ph.D. Candidate, </span><span style="font-family:arial,helvetica,sans-serif;font-size:large"></span><div name="divtagdefaultwrapper">
<div style="font-size:13px"><div style="font-size:13px"><div style="font-size:13px"><font face="Times New Roman, Times, serif"><br></font></div><div style="font-size:13px"><font size="6" face="Times New Roman, Times, serif">Sarah</font></div>
<div style="margin:0px"><font face="Times New Roman, Times, serif">Sarah Cebulski</font></div><div style="margin:0px"><font face="Times New Roman, Times, serif">PhD candidate</font></div><div style="margin:0px"><font face="Times New Roman, Times, serif">Cognitive Science, Carleton University</font></div>
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