# How to create SourceSpaces WITHOUT MRI?

**URL:** <https://mne.discourse.group/t/how-to-create-sourcespaces-without-mri/10886>\
**Category:** Support & Discussions\
**Tags:** meg, bem\
**Created:** [March 6, 2025, 7:58am UTC](https://mne.discourse.group/t/how-to-create-sourcespaces-without-mri/10886 "2025-03-06T07:58:12Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Luessiaw](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/luessiaw/32/3978_2.png) [@Luessiaw](https://mne.discourse.group/u/Luessiaw)\
**Post date:** [March 6, 2025, 7:58am UTC](https://mne.discourse.group/t/how-to-create-sourcespaces-without-mri/10886/1 "2025-03-06T07:58:13Z")

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- MNE version: 1.8.0
- operating system: Windows11

Hello,

I’m trying to do some simulations with the simplest situation, namely the sphere model. I followed the [tutorial](https://mne.tools/stable/auto_tutorials/simulation/10_array_objs.html) and learned how to create MNE-Python data structures from scratch, including `info`,`ConductorModel` objects.

But to build a forword solution, I have to create `SourceSpaces` object as well. And according to the [api document](https://mne.tools/1.8/generated/mne.SourceSpaces.html#mne.SourceSpaces) there are three functions related to this: `setup_source_space`,`setup_volume_source_space` and `read_source_spaces`.

However, the functions `setup_source_space` and `setup_volume_source_space` both need `subject` path as an argument, and `read_source_spaces` needs a `FIF` fie.

**What should I do if I just use a spherical head, WITHOUT MRI** , and create  
a `SourceSpaces` object? Thanks!

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<div class="post-metadata">

**Author:** ![sappelhoff](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/sappelhoff/32/3276_2.png) [@sappelhoff](https://mne.discourse.group/u/sappelhoff)\
**Post date:** [March 11, 2025, 2:40pm UTC](https://mne.discourse.group/t/how-to-create-sourcespaces-without-mri/10886/2 "2025-03-11T14:40:02Z")

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I don’t know about a spherical head, but if you do not have a specific MRI, you could use `fsaverage`, see: [mne.datasets.fetch\_fsaverage — MNE 1.8.0 documentation](https://mne.tools/1.8/generated/mne.datasets.fetch_fsaverage.html#mne.datasets.fetch_fsaverage)