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<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hello Rajesh:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Firstly, the data is recorded in CONTINUOUS mode, and when you import it into EEGLab the data is always in continuous mode.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Secondly, when we record EEG signals, we often make use of triggers (markers that help you to know when specific events happened). Those triggers are recovered
by EEGLab and it’s very frequently to study our EEG signals according to them. For instance, in the paradigm illustrated below, we have four events (4 different kind of sounds) that were marked by four triggers (1,2,3,4). The recording is continuous, but we
have marked the moments that we are interested in. When we “epoch” the data, we indicate to EEGLab what are the segments of the continuous we are interested in. Then the software will extract only the EEG segment that are framed by the triggers (according
to the time points you previously indicate) along the whole continuous data. After this procedure, you stop having continuous data.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><img width="550" height="120" id="Picture_x0020_1" src="cid:image003.jpg@01CCFB22.7A571910"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Finally, as far as I understand, the frames correspond to the number of samples that your equipment record per second. This sample frequency depends on the
characteristics of your equipment, it may be 128 samples per second, 256 samples per second, or 512 samples per second (these are just examples).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hope this helps!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Luz<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> eeglablist-bounces@sccn.ucsd.edu [mailto:eeglablist-bounces@sccn.ucsd.edu]
<b>On Behalf Of </b>D.rajesh<br>
<b>Sent:</b> 03 March 2012 01:45<br>
<b>To:</b> eeglablist@sccn.ucsd.edu<br>
<b>Subject:</b> [Eeglablist] What is meant by 'epoch' and 'frames' in EEG Lab<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="background:white"><span style="color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black"> Hi ,<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black"> I am new to EEG lab and to the subject. I'd like to know what is meant<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black">by 'epoch' in EEG. Isn't the EEG signal is collected continuously in time ? Then where<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black">does the concept of 'epoch' and 'frames' come from and what do they mean ?<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black">Thanks and regards<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black">Rajesh.D<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="color:black"><o:p> </o:p></span></p>
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