<p>It all depends:</p>
<ul>
<li>'<em>...do we need to remove artifacts from the whole EEG signal</em>' - yes you have to in case you are using the entire EEG trace for spectral analysis <em>and</em> if there are artifacts in the first place <em>and</em> if the artifacts share at least part of the frequency spectrum with your target band. In case you do not perform spectral analyses and/or you cut out regions of slow-wave sleep that are devoid of artifacts, and/or you use FFT and the artifact features frequencies outside the band of interest, you don't have to bother about artifacts whatsoever.</li>
<li>'<em>...or do we simply need to extract those epochs that correspond to slow-wave sleep and remove artifacts from those</em>' - extracting relevant epochs increases the FFT power because there is less noise from wake EEG. And of course, if you throw away part of the data, you don't have to worry about artifacts in those ditched data, unless the artifacts swamp the EEG so much that slow-wave sleep isn't recognizable in the trace in the first place.</li>
<li><em>...can artifacts from regions of the EEG that are not slow-wave sleep have an effect on analyses carried out specifically on slow-wave regions</em>' - no, if you extract target epochs and throw away the raw signal outside those epochs, you obviously don't have to worry about the ditched data, but that raises the question why the artifacts would occur only outside your target areas (awake people indeed move more, causing movement artifacts).</li>
</ul>

CC BY-SA 4.0
2024-03-14T21:10:16.683Z
Thanks for the answer
lafinur
CC BY-SA 4.0
2024-03-15T07:21:09.607Z
@lafinur, you're welcome, I will edit a little bit for clarity; I didn't add resources, because this is basic signal processing - an introductory work on EEG or signal processing or electrophysiology will be of great help to you I reckon
AliceD
CC BY-SA 4.0
2024-03-13T10:33:40.497Z
2024-03-15T07:23:46.047Z
2024-03-15T07:23:46.047Z
AliceD
<p>If we want to study a sleep EEG signal in any way (e.g. compute its power spectrum), do we need to remove artifacts from the whole EEG signal, or do we simply need to extract those epochs that correspond to slow-wave sleep and remove artifacts from those?</p>
<p>In other words, can artifacts from regions of the EEG that are not slow-wave sleep have an effect on analyses carried out specifically on slow-wave regions?</p>
<p>I'd appreciate relevant sources. Thanks.</p>

CC BY-SA 4.0
2024-03-10T14:23:15.820Z
The answer is entirely dependent on the specific method used. You're not going to find a citation for "data not used in analysis do not affect analysis" or vice versa.
Bryan Krause
<neuroscience><eeg><signal-processing>
Slow-wave EEG artifact removal
lafinur
# Slow-wave EEG artifact removal

(Asked by: username_0 on 2024-03-09)

If we want to study a sleep EEG signal in any way (e.g. compute its power spectrum), do we need to remove artifacts from the whole EEG signal, or do we simply need to extract those epochs that correspond to slow-wave sleep and remove artifacts from those?

In other words, can artifacts from regions of the EEG that are not slow-wave sleep have an effect on analyses carried out specifically on slow-wave regions?

I'd appreciate relevant sources. Thanks.

**Tags:** neuroscience, eeg, signal-processing

> **Comments:**
> **username_1**: The answer is entirely dependent on the specific method used. You're not going to find a citation for "data not used in analysis do not affect analysis" or vice versa.  

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## 1 answers

### Answer by username_2 on 2024-03-13. Score: 2 | Accepted answer

It all depends:

* '*...do we need to remove artifacts from the whole EEG signal*' - yes you have to in case you are using the entire EEG trace for spectral analysis *and* if there are artifacts in the first place *and* if the artifacts share at least part of the frequency spectrum with your target band. In case you do not perform spectral analyses and/or you cut out regions of slow-wave sleep that are devoid of artifacts, and/or you use FFT and the artifact features frequencies outside the band of interest, you don't have to bother about artifacts whatsoever.
* '*...or do we simply need to extract those epochs that correspond to slow-wave sleep and remove artifacts from those*' - extracting relevant epochs increases the FFT power because there is less noise from wake EEG. And of course, if you throw away part of the data, you don't have to worry about artifacts in those ditched data, unless the artifacts swamp the EEG so much that slow-wave sleep isn't recognizable in the trace in the first place.
* *...can artifacts from regions of the EEG that are not slow-wave sleep have an effect on analyses carried out specifically on slow-wave regions*' - no, if you extract target epochs and throw away the raw signal outside those epochs, you obviously don't have to worry about the ditched data, but that raises the question why the artifacts would occur only outside your target areas (awake people indeed move more, causing movement artifacts).

> **Comments:**
> **username_0**: Thanks for the answer  
> **username_2**: @username_0, you're welcome, I will edit a little bit for clarity; I didn't add resources, because this is basic signal processing - an introductory work on EEG or signal processing or electrophysiology will be of great help to you I reckon  

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