[FieldTrip] NAI noise normalization beamforming

Merkel, Nina nina.merkel at esi-frankfurt.de
Thu Sep 22 13:57:56 CEST 2022

Dear Fieldtrip Community,

I am using NAI normalization for my resting state MEG data. It does something to my data that I don't quite understand­čś│.

Before normalization I have the average power of groupA > groupB (also true for the sensor data). After normalization the pattern turns, while the variance of groupA decreases and the variance in groupB increases. I am not exactly sure what that means. Is the change in power completely explainable by the higher variance of groupA? Are there any limitations of using NAI? Is there a situation where I should not use it?

I am especially wondering about the variance since during my whole analysis it was quite clear that this a a major difference between the groups.

I am posting this question since I was not able to figure out how exactly the NAI is estimated during source reconstruction.

Does anyone have more information about the computation of NAI?

Thanks so much

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20220922/ffaaa0ae/attachment.htm>

More information about the fieldtrip mailing list