<p><span style="padding: 3px 10px; border-radius: 5px; color: #ffffff; font-weight: bold; display: inline-block; background-color: #ff0000;"> External Email - Use Caution </span></p><p></p><div dir="ltr"><div>here's some context to why mne treats the axial gradiometers as magnetometers from a conversation I had with Matti four years ago. We should probably have this documented somewhere:</div><div><br></div><div><br></div><div style="margin-left:40px">This is on purpose. “magnetometers” includes magnetometers and axial
gradiometers. The field is still computed correctly as defined by the
coil type. It is reasonable to have the units as Tesla in axial
gradiometers, since the compensation coil in this case is relatively far
from the brain so that the signal measured is still from the coil loop
close to the brain. <br>
<br>
In planar gradiometers both parts of the figure-of-eight loops are in
the cerebral magnetic field and, therefore, we use T/m: we measure a
gradient of the field of interest. Another way to say this is that the
figure-of-eight loop performs a dual purpose: the external homogeneous
disturbances are attenuated and, at the same time, the device measures a
derivative of the brain’s magnetic field.<br>
<br>
I hope this helps,<br>
Matti<br></div><div><div><div class="m_2943265882032459964gmail-im" style="margin-left:40px">
<br>
> On Apr 13, 2015, at 12:38 PM, Teon Brooks <<a href="mailto:teon.brooks@gmail.com" target="_blank">teon.brooks@gmail.com</a>> wrote:<br>
> <br>
> Hi Matti,<br>
> <br>
> I was looking through the code for the KIT reader in MNE and what I
am noticed is that although we have axial gradiometers, the channels
are being marked as magnetometers. I was wondering what is the reasoning
behind this. Also, the units are marked as Tesla instead of Tesla per
meter, another correspondence to the magnetometer. The same behavior
also occurs for CTF data.<br>
> <br>
> <br>
> Best,<br>
> -teon</div><div class="m_2943265882032459964gmail-im"><br></div><div class="m_2943265882032459964gmail-im"><br></div></div></div><div>Hope this helps,<br></div><div><br> </div><div><div><div dir="ltr" class="m_2943265882032459964m_-4744061209643497488gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>Best,</div><div>Teon<br></div><div>--<br></div><div><a href="https://teonbrooks.github.io" style="font-size:12.8px" target="_blank">@teonbrooks</a></div></div></div></div></div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Sep 6, 2019 at 2:01 PM <<a href="mailto:mne_analysis-request@nmr.mgh.harvard.edu" target="_blank">mne_analysis-request@nmr.mgh.harvard.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Send Mne_analysis mailing list submissions to<br>
<a href="mailto:mne_analysis@nmr.mgh.harvard.edu" target="_blank">mne_analysis@nmr.mgh.harvard.edu</a><br>
<br>
To subscribe or unsubscribe via the World Wide Web, visit<br>
<a href="https://mail.nmr.mgh.harvard.edu/mailman/listinfo/mne_analysis" rel="noreferrer" target="_blank">https://mail.nmr.mgh.harvard.edu/mailman/listinfo/mne_analysis</a><br>
or, via email, send a message with subject or body 'help' to<br>
<a href="mailto:mne_analysis-request@nmr.mgh.harvard.edu" target="_blank">mne_analysis-request@nmr.mgh.harvard.edu</a><br>
<br>
You can reach the person managing the list at<br>
<a href="mailto:mne_analysis-owner@nmr.mgh.harvard.edu" target="_blank">mne_analysis-owner@nmr.mgh.harvard.edu</a><br>
<br>
When replying, please edit your Subject line so it is more specific<br>
than "Re: Contents of Mne_analysis digest..."<br>
<br>
<br>
Today's Topics:<br>
<br>
1. Re: A bug in 'pick_types' function for CTF dataset<br>
(Alday, Phillip)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Fri, 6 Sep 2019 17:58:48 +0000<br>
From: "Alday, Phillip" <<a href="mailto:Phillip.Alday@mpi.nl" target="_blank">Phillip.Alday@mpi.nl</a>><br>
Subject: Re: [Mne_analysis] A bug in 'pick_types' function for CTF<br>
dataset<br>
To: Discussion and support forum for the users of MNE Software<br>
<<a href="mailto:mne_analysis@nmr.mgh.harvard.edu" target="_blank">mne_analysis@nmr.mgh.harvard.edu</a>><br>
Cc: "<a href="mailto:fanwang@ibp.ac.cn" target="_blank">fanwang@ibp.ac.cn</a>" <<a href="mailto:fanwang@ibp.ac.cn" target="_blank">fanwang@ibp.ac.cn</a>><br>
Message-ID: <<a href="mailto:bcf661e7-8d45-4e37-a706-91726f177477@mpi.nl" target="_blank">bcf661e7-8d45-4e37-a706-91726f177477@mpi.nl</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
External Email - Use Caution <br>
<br>
If you look at <a href="http://raw.info" rel="noreferrer" target="_blank">raw.info</a>, you'll see that MNE thinks that the CTF sensors are all mag and not grad. This is something I noticed recently and haven't had time to examine systematically enough to put in a pull request for yet.<br>
<br>
Phillip<br>
<br>
Sent from my mobile, please excuse the brevity.<br>
________________________________<br>
Von: boo <<a href="mailto:1401110602@pku.edu.cn" target="_blank">1401110602@pku.edu.cn</a>><br>
Gesendet: Freitag, 6. September 2019 20:20<br>
An: <a href="mailto:mne_analysis@nmr.mgh.harvard.edu" target="_blank">mne_analysis@nmr.mgh.harvard.edu</a><br>
Cc: <a href="mailto:fanwang@ibp.ac.cn" target="_blank">fanwang@ibp.ac.cn</a><br>
Betreff: [Mne_analysis] A bug in 'pick_types' function for CTF dataset<br>
<br>
<br>
External Email - Use Caution<br>
<br>
Dears:<br>
<br>
I am wondering whether 'mne.pick_types' has a bug for CTF dataset. When I use ?gradiometer? as parameter there is no gradiometer channels were selected (mne.pick_types(<a href="http://raw_data.info" rel="noreferrer" target="_blank">raw_data.info</a><<a href="http://raw_data.info" rel="noreferrer" target="_blank">http://raw_data.info</a>>, meg='grad?)), while the 275 gradiometer channels could be selected by using the ?magnetometer? as parameter (mne.pick_types(<a href="http://raw_data.info" rel="noreferrer" target="_blank">raw_data.info</a><<a href="http://raw_data.info" rel="noreferrer" target="_blank">http://raw_data.info</a>>, meg=?mag?)) as shown by the screenshot. I report this information please let me know if I misunderstood anything.<br>
<br>
<br>
My system and MNE environment is shown below:<br>
<br>
Platform: Darwin-18.7.0-x86_64-i386-64bit<br>
Python: 3.6.8 |Anaconda, Inc.| (default, Dec 29 2018, 19:04:46) [GCC 4.2.1 Compatible Clang 4.0.1 (tags/RELEASE_401/final)]<br>
Executable: /anaconda3/envs/mne/bin/python<br>
CPU: i386: 12 cores<br>
Memory: 32.0 GB<br>
mne: 0.19.dev0<br>
numpy: 1.16.4 {blas=mkl_rt, lapack=mkl_rt}<br>
scipy: 1.2.1<br>
matplotlib: 3.1.0 {backend=MacOSX}<br>
sklearn: 0.21.2<br>
nibabel: 2.4.0<br>
mayavi: 4.6.2 {qt_api=pyqt5, PyQt5=5.12.1}<br>
cupy: Not found<br>
pandas: 0.24.2<br>
dipy: 0.16.0<br>
<br>
<br>
Best regards<br>
bo<br>
<a href="mailto:bo.zhang@pku.edu.cn" target="_blank">bo.zhang@pku.edu.cn</a><mailto:<a href="mailto:bo.zhang@pku.edu.cn" target="_blank">bo.zhang@pku.edu.cn</a>><br>
<br>
<br>
<br>
[cid:5c200c35-eda5-44ed-8249-65f2263f8856]<br>
-------------- next part --------------<br>
An HTML attachment was scrubbed...<br>
URL: <a href="http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20190906/0f228f24/attachment.html" rel="noreferrer" target="_blank">http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20190906/0f228f24/attachment.html</a> <br>
-------------- next part --------------<br>
A non-text attachment was scrubbed...<br>
Name: screenshot.png<br>
Type: image/png<br>
Size: 935676 bytes<br>
Desc: screenshot.png<br>
Url : <a href="http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20190906/0f228f24/attachment.png" rel="noreferrer" target="_blank">http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20190906/0f228f24/attachment.png</a> <br>
<br>
------------------------------<br>
<br>
_______________________________________________<br>
Mne_analysis mailing list<br>
<a href="mailto:Mne_analysis@nmr.mgh.harvard.edu" target="_blank">Mne_analysis@nmr.mgh.harvard.edu</a><br>
<a href="https://mail.nmr.mgh.harvard.edu/mailman/listinfo/mne_analysis" rel="noreferrer" target="_blank">https://mail.nmr.mgh.harvard.edu/mailman/listinfo/mne_analysis</a><br>
<br>
End of Mne_analysis Digest, Vol 140, Issue 9<br>
********************************************<br>
</blockquote></div>