[Eeglablist] Source localization and hippocanpus

[Makoto Miyakoshi]

In this preprint, the authors (me) reported that "80% of
[pre-qualified brain] ICs were localized at physiologically implausible
depths (19–26 mm)".
https://urldefense.com/v3/__https://www.medrxiv.org/content/10.64898/2026.01.23.26344529v2__;!!Mih3wA!C1nh8ACP-VTlqgwY31VeWS44yEGmEYniQ2NwoeqvKH5ZL4LvyhF548fevyL6twMijeDcEbe38QjQbt4_yBNR6FpDr0g$ 

So I would say there is always a systematic bias in a single dipole
fitting. I demonstrated it using a simple simulation in the above
manuscript.
I do not think it is because ICA is used. ICA, or ERP, imposes a model to
data to extract a stationary aspect of it. Your analysis method determines
what you can observe.

Another view of this 'depth bias' is that most of you simply misunderstand
what EEG 'source' would look like; it is in fact massive traveling waves
which you would never even think of 'localization'.
https://urldefense.com/v3/__https://elifesciences.org/reviewed-preprints/100674v1__;!!Mih3wA!C1nh8ACP-VTlqgwY31VeWS44yEGmEYniQ2NwoeqvKH5ZL4LvyhF548fevyL6twMijeDcEbe38QjQbt4_yBNRb2YX3CE$ 

Electric Fields of the Brain (Nunez and Srinivasan, 2006) also suggest a
similar view; this book even asks 'why do you assume that EEG sources are
localizable?'

Makoto

On Tue, Feb 24, 2026 at 12:11 PM Евгений Машеров via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> I understand that a pretty picture is not proof, but it can be useful as
> food for thought.
>
> https://urldefense.com/v3/__https://link.springer.com/article/10.1134/S0362119722700153__;!!Mih3wA!DTRo-WoUjLWsdEs9GAsBD53DyO2FOPeN0bq9CSpMgwe0-iLL7tMa09cehjO9ghsIwwQGn9ha77bQ2w3AQc6JMdEb7eE$
>
>
> > Hi Eugen,
> >
> > in my own past work I found sources (expected) in hippocampal/temporal
> regions. The ICA and volume localization I used implicated parts parts of
> the temporal lobe together with the hippocampus.
> >
> > I'm glad you're looking into this.
> >
> > Philip
> >
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