<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Dear Baris,<div><br></div><div>regarding your cluster, you should be very careful when using 2 STUDY to process the same datasets. There is a warning in EEGLAB that automatically pops up in case you have such a configuration: the two STUDY could potentially conflict with each other (the two studies could share the same data files and overwrite each other files). To process a given set of datafiles, it is better to create one STUDY and several design within a single STUDY. This might be the reason why you are observing the same clusters?</div><div><br></div><div>In the future, each STUDY will generate MD5 checksums for each design cell, and this conflict will be removed.</div><div>Best,</div><div><br></div><div>Arno </div><div><br><div><div>On Aug 30, 2011, at 6:00 PM, Baris Demiral wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">Dear all,<div><br></div><div>My question is related to the Independent Component - ERP component mapping. A bit theoretical. I will make a distinction between IC; independent component, and ERPC; ERP component.</div><div><br>
</div><div>I conducted ICA (runica-extended) by feeding the four conditions of my experiment (2x2; stimulus type x stimulus features).</div>
<div>I then separated two factors (stimulus types) from each other, and built two study files for each factor to compare the levels (features) in ERP and IC domains.</div><div><br></div><div>Then I did pre-clustering with PCA reduction to 10, then hierarchical clustering for the ICs in each study file separately, defining 3 final clusters.</div>
<div><br></div><div>Interesting thing was that one of the IC clusters' scalp map of study1 was almost identical to one of the IC clusters' scalp map of the study2, BUT in ERP waveforms these two ICs were showing two distinct "ERP components" (as eye balled over the ERP difference between the conditions, one condition differing from the other as in classical ERP component selection etc..) I was expecting that the IC clusters with the same scalp topography should map to the similar ERP waveforms (components) for both factors. </div>
<div><br></div><div>Is this possible? Can I conclude that the same IC and maybe the same cortical area generate two different ERP components depending on the condition?</div><div><div> </div>
-- <br>SB Demiral, PhD.<br>Department of Psychology <br>7 George Square<br>The University of Edinburgh<br>Edinburgh, EH8 9JZ<br>UK<br>Phone: <a href="tel:%2B44%20%280131%29%206503063" value="+441316503063" target="_blank">+44 (0131) 6503063</a><br>
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