
<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><font class="Apple-style-span" face="Helvetica, Arial, sans-serif">Hi <span id="wsPlainWord_0" class="blackClass"><span id="wsPlainWord_0"><span id="wsPlainWord_0"><span class="blackClass" id="wsPlainWord_0">Eriksen</span></span></span></span>,<br> <span id="wsPlainWord_1" class="blackClass"></span><span id="wsPlainWord_3" class="blackClass"><span id="wsPlainWord_1" class="blackClass"><span id="wsPlainWord_1"><span id="wsPlainWord_1">The</span></span></span></span> <span id="wsPlainWord_4"><span id="wsPlainWord_2"><span id="wsPlainWord_2"><span id="wsPlainWord_2">original</span></span></span></span> <span id="wsPlainWord_5"><span id="wsPlainWord_3"><span id="wsPlainWord_3"><span class="blackClass" id="wsPlainWord_3">data</span></span></span></span> <span id="wsPlainWord_6"><span id="wsPlainWord_4"><span id="wsPlainWord_4" class="blackClass"><span id="wsPlainWord_4">has</span></span></span></span> <span id="wsPlainWord_7" class="blackClass"><span id="wsPlainWord_5"><span id="wsPlainWord_5"><span id="wsPlainWord_5">been</span></span></span></span> <span id="wsPlainWord_8" class="blackClass"><span id="wsPlainWord_6"><span id="wsPlainWord_6" class="blackClass"><span id="wsPlainWord_6">whitened</span></span></span></span> (to <span id="wsWordAdd11"></span><span id="wsWord11" class="mceItemWSSpelling">decorrelate</span> <span id="wsPlainWord_9"><span id="wsPlainWord_7"><span id="wsPlainWord_7"><span id="wsPlainWord_7">the</span></span></span></span> <span id="wsPlainWord_10"><span id="wsPlainWord_8"><span id="wsPlainWord_8"><span id="wsPlainWord_8">channels</span></span></span></span>) <span id="wsPlainWord_11" class="blackClass"><span id="wsPlainWord_9"><span id="wsPlainWord_9"><span id="wsPlainWord_9">before</span></span></span></span> be <span id="wsPlainWord_12"><span id="wsPlainWord_10"><span id="wsPlainWord_10"><span id="wsPlainWord_10">submitted</span></span></span></span> <span id="wsPlainWord_13" class="blackClass"><span id="wsPlainWord_11"><span id="wsPlainWord_11"><span id="wsPlainWord_11">into</span></span></span></span> <span id="wsPlainWord_14"><span id="wsPlainWord_12"><span id="wsPlainWord_12"><span id="wsPlainWord_12">the</span></span></span></span> <span id="wsPlainWord_15"><span id="wsPlainWord_13"><span id="wsPlainWord_13"><span id="wsPlainWord_13">ICA</span></span></span></span> <span id="wsPlainWord_16"><span id="wsPlainWord_14"><span id="wsPlainWord_14"><span id="wsPlainWord_14">decomposition procedure</span></span></span></span>.<br> So <span id="wsPlainWord_17"><span id="wsPlainWord_15" class="blackClass"><span id="wsPlainWord_15"><span id="wsPlainWord_15">the</span></span> <span id="wsPlainWord_16"><span id="wsPlainWord_16">ICA</span></span> <span id="wsPlainWord_17"><span id="wsPlainWord_17">activations</span></span> <span id="wsPlainWord_18"><span class="blackClass" id="wsPlainWord_18">should</span></span> be <span id="wsPlainWord_19" class="blackClass"><span id="wsPlainWord_19">given</span></span> by </span></span> ICA_activations = <span id="wsPlainWord_18" class="blackClass"><span id="wsPlainWord_16"><span id="wsPlainWord_20"><span id="wsPlainWord_20">wts</span></span></span></span> * <span id="wsPlainWord_19"><span id="wsPlainWord_17"><span id="wsPlainWord_21"><span id="wsPlainWord_21">sph</span></span></span></span> * <span id="wsPlainWord_20"><span id="wsPlainWord_18"><span id="wsPlainWord_22"><span id="wsPlainWord_22">data</span></span></span></span>;<br> <span id="wsPlainWord_21"><span id="wsPlainWord_19" class="blackClass"><span id="wsPlainWord_23"><span id="wsPlainWord_23">And</span></span></span></span> <span id="wsPlainWord_22"><span id="wsPlainWord_20" class="blackClass"><span id="wsPlainWord_24"><span id="wsPlainWord_24">the</span></span></span></span> <span id="wsPlainWord_23"><span id="wsPlainWord_21" class="blackClass"><span id="wsPlainWord_25"><span id="wsPlainWord_25">reversed</span></span></span></span> <span id="wsPlainWord_24" class="blackClass"><span id="wsPlainWord_22"><span id="wsPlainWord_26" class="blackClass"><span id="wsPlainWord_26">algorithm</span></span></span></span> <span id="wsPlainWord_25"><span id="wsPlainWord_23"><span id="wsPlainWord_27" class="blackClass"><span id="wsPlainWord_27">should</span></span></span></span> be <span id="wsPlainWord_28"><span id="wsPlainWord_28">given</span></span> by eeg_activations=<span id="wsPlainWord_26"><span id="wsPlainWord_24"><span id="wsPlainWord_29"><span id="wsPlainWord_29">pinv</span></span></span></span>(<span id="wsPlainWord_27"><span id="wsPlainWord_25"><span id="wsPlainWord_30"><span id="wsPlainWord_30">wts</span></span></span></span>*<span id="wsPlainWord_28" class="blackClass"><span id="wsPlainWord_26"><span id="wsPlainWord_31"><span id="wsPlainWord_31">sph</span></span></span></span>)*ICA_activations;<br><br><span id="wsPlainWord_29"><span id="wsPlainWord_27"><span id="wsPlainWord_32" class="blackClass"><span id="wsPlainWord_32">Hope</span></span> <span id="wsPlainWord_33"><span class="blackClass" id="wsPlainWord_33">this</span></span> is <span id="wsPlainWord_34" class="blackClass"><span id="wsPlainWord_34">helpful</span></span> <span id="wsPlainWord_35" class="blackClass"><span id="wsPlainWord_35">for</span></span> <span id="wsPlainWord_36" class="blackClass"><span id="wsPlainWord_36">you</span></span></span></span><span id="wsPlainWord_30"><span id="wsPlainWord_28" class="blackClass"></span></span><span id="wsPlainWord_31"><span id="wsPlainWord_29" class="blackClass"></span></span><span id="wsPlainWord_32"><span id="wsPlainWord_30" class="blackClass"></span></span>!<br>-<span id="wsPlainWord_33"><span id="wsPlainWord_31" class="blackClass"><span id="wsPlainWord_37"><span id="wsPlainWord_37">YANG</span></span></span></span>!</font></div><div><font class="Apple-style-span" face="Helvetica, Arial, sans-serif"><br></font></div><div><font class="Apple-style-span" color="#FF0000" face="Helvetica, Arial, sans-serif"><b><br></b></font><div>

<div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; font-family: STHeiti; font-size: 12px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: STHeiti; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="font-family: Verdana; font-size: 14px; ">Yang Zhang<br>------------------------------------<br>Department of Psychology<br>Northeast Normal University<br>Chang Chun, Ji Lin, China<br>130024<br><a href="mailto:Zhangyang873@yahoo.com.cn">zhangyang873@yahoo.com.cn</a></span></div><div><span class="Apple-style-span" style="font-family: Verdana; font-size: 14px; "><a href="mailto:zhangyang873@gmail.com">zhangyang873@gmail.com</a><br>-------------------------------------</span></div><div><br></div></div></span><br class="Apple-interchange-newline"></div><br class="Apple-interchange-newline"><br class="Apple-interchange-newline">

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<br><div><div>On Jun 25, 2011, at 8:47 AM, Jeff Eriksen wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); font-size: 14px; font-family: Calibri, sans-serif; "><div><div>I am hoping to do some specialized processing in Matlab using the icawinv and icaweights, part of the the ALLEEG Matlab structure. First I tried to reconstruct the EEG with one component removed but it did not look quite right. Next I decided to leave all components in and see if I could construct all the component time courses and then use them to reconstruct the whole EEG epoch. This did not come out right either. To get the components, I do this:</div><div><br></div><div>comp_acts = ica_weights * eeg</div><div><br></div><div>Then to get the EEG back I do this:</div><div><br></div><div>eeg-recon = ica<span style="font-style: italic; ">winv * comp_acts</span></div><div><br></div><div>But find that the reconstructed EEG does not quire match the original EEG, and is much larger in amplitude as well.</div><div><br></div><div>I must not be understanding fully what these matrices are.</div><div><br></div><div>Thanks,</div><div>-Jeff</div></div><div><br></div></div>

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