<html><head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" style="display:none;"><!-- P {margin-top:0;margin-bottom:0;} --></style>
</head>
<body dir="ltr">
<div id="divtagdefaultwrapper" style="font-size:12pt;color:#000000;font-family:Calibri,Helvetica,sans-serif;" dir="ltr">
<p>Hello,</p>
<p><br>
</p>
<p>I am plotting outcomes from a frequency analysis of resting state sensor space EEG data, for the analysis I use the code below, and then plot with singleplotER, if I first high pass filter my data at 1Hz during a prepocessing step, my plotting shows no activity
until 35Hz then it spikes to a plateau for the rest of he higher frequencies, after a log transform I get a sine wave like shape. With no HP filter the data look like normal power spectrum data, why is the HP filter changing my data in this way?</p>
<p><br>
</p>
<div> cfg = [];<br>
cfg.output = 'pow' ;<br>
cfg.method = 'mtmfft';<br>
cfg.pad = 'nextpow2';<br>
cfg.taper = 'hanning';<br>
cfg.foilim = [3 50]; %change for appropriate range of frequencies<br>
% cfg.tapsmofrq = [2] ;<br>
cfg.keeptrials = 'no';<br>
%EEG_freq_segmented{i_run} = ft_freqanalysis(cfg, data_segmented_no_artifacts);<br>
%EEG_freq_segmented{i_run} = ft_freqanalysis(cfg, data_segmented);<br>
% freqfourier{i_run} = ft_freqanalysis(cfg, data_segmented_preproc_ICArm_no_artifacts);<br>
freqfourier= ft_freqanalysis(cfg, data_segmented_no_artifacts);<br>
%%%%%%log transform%%%%%%%%%%%%% <br>
cfg = [];<br>
cfg.parameter = 'powspctrm';<br>
cfg.operation = 'log10';<br>
freqfourier = ft_math(cfg, freqfourier);<br>
<br>
Thank you,<br>
Patrick<br>
</div>
<br>
<p></p>
</div>
<p><span style="font-size:11px;font-family: Calibri, Arial, Helvetica, sans-serif;"><span style="color: rgb(128, 128, 128);"><tt><em>Confidentiality Notice: This message and any attachments are only for the intended recipient(s) and may contain confidential,
privileged and/or protected health information. If you are not the intended recipient of this message, please: 1) be advised that unauthorized review, use, copying, disclosure, or distribution is strictly prohibited and may be unlawful; 2) notify the sender
of the delivery by reply e-mail or contact Shirley Ryan AbilityLab's Privacy Officer at 312.238.0766 or
</em></tt></span><tt><em><a href="mailto:privacyofficer@sralab.org"><span style="color: rgb(128, 128, 128);">privacyofficer@sralab.org</span></a></em></tt><span style="color: rgb(128, 128, 128);"><tt><em>; and 3) delete and destroy all copies of the message
and its attachments. Thank you.</em></tt></span></span></p>
</body>
</html>