# EEG Source Reconstruction with eLORETA: Choosing the snr, normalising source time courses, removing subcortical structures effect and spatial resolution

**URL:** <https://mne.discourse.group/t/eeg-source-reconstruction-with-eloreta-choosing-the-snr-normalising-source-time-courses-removing-subcortical-structures-effect-and-spatial-resolution/10759>\
**Category:** Support & Discussions\
**Tags:** list-archive, source-localization, eeg\
**Created:** [January 30, 2025, 7:53pm UTC](https://mne.discourse.group/t/eeg-source-reconstruction-with-eloreta-choosing-the-snr-normalising-source-time-courses-removing-subcortical-structures-effect-and-spatial-resolution/10759 "2025-01-30T19:53:56Z")\
**Posts on this page:** 1\
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**Author:** ![richard](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/richard/32/15_2.png) [@richard](https://mne.discourse.group/u/richard)\
**Post date:** [January 31, 2025, 5:08pm UTC](https://mne.discourse.group/t/eeg-source-reconstruction-with-eloreta-choosing-the-snr-normalising-source-time-courses-removing-subcortical-structures-effect-and-spatial-resolution/10759/4 "2025-01-31T17:08:56Z")

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> [@Rohmer](#):
>
> - I appreciate your clarification about choosing the right `lambda2`. How would you go around setting this parameter given the inherent circularity in picking a good value? Is sensor level `snr` as can be guessed through `evoked.plot_white(noise_cov_reg, time_unit="s")` or other means truly a wrong proxy for source level `snr`?

For evoked data, set SNR to 3  
For continuous data, set it to 1

See:

> [@Estimating the regularization parameter for HCP MEG resting state source reconstruction](https://mne.discourse.group/t/estimating-the-regularization-parameter-for-hcp-meg-resting-state-source-reconstruction/5177/15):
>
> @Dominik I just asked @agramfort about this while we were fighting with the coffee machine (spoiler: we won! muscle coffee) He said this parameter (SNR of 3 for averaged, 1 for non-averaged data) “was established by Matti Hämäläinen 20 years ago”, and that “no one touches this parameter”. Hence … I would say, case closed. wink Best wishes, Richard

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