[Eeglablist] Source localization and hippocanpus

[Kevin Spencer]

Hi Makoto,

Here is something that sounds similar to what you propose:

Goldenholz DM, Ahlfors SP, Hämäläinen MS, Sharon D, Ishitobi M, Vaina LM, Stufflebeam SM (2009) Mapping the signal-to-noise-ratios of cortical sources in magnetoencephalography and electroencephalography. Human brain mapping 30:1077–1086.
10.1002/hbm.20571

We definitely need more work like this.

Cheers,
Kevin

---------------------------------------------------------------------------------
Kevin M. Spencer, Ph.D.
Research Health Scientist, VA Boston Healthcare System
Associate Professor of Psychiatry, Harvard Medical School
---------------------------------------------------------------------------------


On Thursday, February 5th, 2026 at 8:59 PM, Makoto Miyakoshi via eeglablist <eeglablist at sccn.ucsd.edu> wrote:

> Hi all,
> 
> If we develop an EEG version of this solution, we can answer the question.
> https://urldefense.com/v3/__https://www.sciencedirect.com/science/article/abs/pii/S105381190291102X?via*3Dihub__;JQ!!Mih3wA!HwsurlhLmCGSy6wCiD5l9SSb_thJ_sxE8EJlEsKXD0KDFSdVaEdxAC8dST2UIXhjpckQKpFDlX_vA2AqAYmVO9BujEY$
> Does anyone object to this claim?
> 
> Then, why don't we just do it?
> 
> That is because---Komal is already working on it. The project code is 'EEG
> impossibility atlas'.
> 
> Makoto
> 
> On Tue, Feb 3, 2026 at 4:22 AM Cedric Cannard via eeglablist <
> eeglablist at sccn.ucsd.edu> wrote:
> 
> > Yongxian,
> > 
> > Wow… this looks potentially incredibly groundbreaking. If the claims hold
> > up to further validation, it could address so many longstanding limitations
> > across neuroimaging modalities. Especially the low temporal resolution of
> > fMRI and the recent finding by Epp et al (2025) that ~40% of voxels with
> > significant BOLD changes showed oxygen metabolism going in the opposite
> > direction to what BOLD indicated (decreased CMRO₂).
> > 
> > I’ll be following the replication efforts closely. Thanks for sharing!
> > 
> > Cedric
> > 
> > Sent from Proton Mail for iOS.
> > 
> > -------- Original Message --------
> > On Monday, 02/02/26 at 15:51 Qian, Yongxian via eeglablist <
> > eeglablist at sccn.ucsd.edu> wrote:
> > Dear Eugen and Makoto,
> > 
> > I am very interested in this discussion about the EEG source localization,
> > especially at deep brain regions like the hippocanspus.
> > 
> > Accidentally, we just completed a research work about quantum sensing MRI
> > (qsMRI) for detection of neuronal electrical activity (
> > https://urldefense.com/v3/__https://arxiv.org/pdf/2601.16423__;!!Mih3wA!A5WTWbxQ1Fe5li2NSeeVa9LvVA5-JOIOgdygiOdvNUggK74DYpMfj4VuVR1y50JThTDHm-jp_iZrnUZdrXmd8Yz2ZPcYNUvvSQ$
> > ), in which neuronal firing source localization is definitive through MRI
> > imaging.
> > 
> > The qsMRI may help you all to clarify some issues regarding the EEG signal
> > source localization.
> > 
> > By the way, our group uses an MRI-compitable EEG system (32Ch, Brain
> > Vison) to study sleep impact on CSF flow in normal aging population (25 -
> > 100 years old).
> > 
> > Best,
> > 
> > Yongxian
> > 
> > ----------------------------------------------------------------------------------------------------
> > 
> > Yongxian Qian, PhD
> > 
> > Assistant Professor, Center for Biomedical Imaging, Department of Radiology
> > 
> > Investigator, Neuroscience Institute, Department of Neuroscience and
> > Physiology
> > 
> > Training Faculty, Vilcek Institute of Graduate Biomedical Sciences
> > 
> > NYU Grossman School of Medicine
> > 
> > Editorial Board Member, Scientific Reports, a Nature portfolio journal
> > 
> > Guest Editor, "Quantum Technologies for Healthcare", Scientific Reports, a
> > Nature portfolio journal
> > 
> > https://urldefense.com/v3/__https://www.nature.com/collections/bebgeadadf/guest-editors__;!!Mih3wA!A5WTWbxQ1Fe5li2NSeeVa9LvVA5-JOIOgdygiOdvNUggK74DYpMfj4VuVR1y50JThTDHm-jp_iZrnUZdrXmd8Yz2ZPfsJw6mfQ$
> > 
> > NYU Langone Health
> > 
> > Center for Biomedical Imaging (CBI)
> > 
> > 660 First Avenue, 4th Floor
> > 
> > New York, NY 10016
> > 
> > T: 212-263-1159
> > 
> > Yongxian.Qian at nyulangone.org
> > 
> > ----------------------------------------------------------------------------------------------------
> > 
> > ________________________________
> > From: eeglablist eeglablist-bounces at sccn.ucsd.edu on behalf of Евгений
> > Машеров via eeglablist eeglablist at sccn.ucsd.edu
> > Sent: Saturday, January 31, 2026 7:10 AM
> > To: Makoto Miyakoshi mmiyakoshi at ucsd.edu
> > Cc: EEGLAB List eeglablist at sccn.ucsd.edu
> > Subject: Re: [Eeglablist] Source localization and hippocanpus
> > 
> > [EXTERNAL]
> > 
> > The question of what source amplitude is required for a signal from deep
> > brain regions to be registered on the scalp arose when Professor Olga
> > Grindel, then head of the Clinical Neurophysiology Laboratory, suggested I
> > study and use the dipole localization method (Yu. M. Koptelov's BraibLoc
> > program) for clinical applications. Preliminary calculations showed
> > completely non-physiological amplitude values, and I approached the task
> > with extreme skepticism. However, not only were deep brain sources detected
> > by this method, but they were also confirmed during surgeries. Since I
> > didn't want to portray Admiral Nelson putting a telescope to his missing
> > eye and declaring "I see nothing," I also didn't like the explanation that
> > the signal from deep brain sources travels along neural pathways to the
> > cortex and we see the signal from the cortex, as this contradicted the
> > entire mathematical apparatus of localization. I tried to find other
> > explanations. One of them is monopole sources, the potential from which
> > decreases more slowly than from dipole sources. But then it's unclear why
> > they are detected by algorithms that implicitly assume dipoles. It's
> > possible that we're dealing with a pair of monopoles with opposite signs,
> > so a dipole at the point between them provides a good approximation.
> > Another explanation is a system of synchronized dipoles along the surface,
> > creating a potential that decreases significantly more slowly at distances
> > comparable to the size of the surface. Secondary dipoles arising at the
> > boundaries of regions of different conductivity may also contribute. It
> > seems to me that all of these mechanisms are at work, along with something
> > else that's still unclear. Sources of these two types—monopole and
> > dipole—as well as quadrupole, operate in all brain structures, but the
> > ability to register a signal from them on the scalp depends on the distance
> > and orientation of the source, to varying degrees for these three types,
> > but also on the synchronization between them. It seems to me (but this
> > doesn't even deserve the title of a full-fledged hypothesis, only a
> > suggestion) that monopoles are associated with low-frequency activity (but
> > not just delta, possibly up to alpha or even slightly higher) and the
> > formation of sinusoidal oscillations, and their physiological role is the
> > regulation of biochemical processes, in particular metabolism and ion
> > concentration levels. Dipoles are a product of neural activity itself,
> > EPSPs and IPSPs, while quadrupoles (not recorded from the scalp, except in
> > cases of synchronization of groups of sources) are associated with action
> > potentials. Perhaps such a complication of the generation model will not
> > only clarify the physiology of the brain but also provide a mathematical
> > framework more adequate to the problem.
> > 
> > Eugen Masherov
> > 
> > > Hi all,
> > > 
> > > I've read this discussion with great interest!
> > > Here are my thoughts.
> > > 
> > > 1. If I adopt a conventional dogma of generative mechanism of EEG i.e.,
> > > all/most of scalp-measured EEG signals entirely generated by
> > > post-synaptic
> > > membrane potential in cortical surface (Electric Fields of the Brain,
> > > EFB,
> > > by Nunez and Srinivasan 2006 adopts this assumption, for example),
> > > measuring EEG signals generated in the hippocampus using a conventional
> > > EEG
> > > recorder (i.e., sensitivity limit > 1 microV) would be impossible
> > > primarily
> > > because of the geometry (too small, too deep, rolled shape, etc..)
> > > 2. However, a modern electrodiffusive neural-extracellular-glia (edNEG)
> > > model indicates the possibility that non-synaptic source activity affects
> > > scalp EEG as well, which is much less studied. See Saetra et al. (2021)
> > > for
> > > full details (but this one is super technical).
> > 
> > https://urldefense.com/v3/__https://journals.plos.org/ploscompbiol/article?id=10.1371*journal.pcbi.1008143*libraryItemId=11397962__;LyM!!Mih3wA!HKOkIU0i7obnN2bi48-tFzXvjoC4GDRCU_PNDuM4JjgXO5eU64BD7_JedfcOwGzJ1sa-MaQUQsJcYI8SaWZ6uQfdIgo$
> > 
> > > 3. I read the dispute between Joseph's group and Mike's group with great
> > > interest. If I stand on the conventional viewpoint, I agree with Mike,
> > > and
> > > I usually stand on it. But that does not mean non-conventional source
> > > cannot exist, particularly if it is observed in a low-frequency range
> > > (below delta). After all, we do not know EEG phenomenon completely, so we
> > > are not there yet to make an a priori prediction that can properly bound
> > > the observation (i.e., "If we observe X under certain conditions, it MUST
> > > BE noise because it cannot be there from biophysics!")
> > > 4. That said, I still want to emphasize that learning the conventional
> > > synaptic dogma and EEG's unique scaling law (i.e., volume conductor
> > > theory,
> > > including what I call 'transducer array effect' of a dipole layer) is
> > > very
> > > important. For those who are curious, below I provide two sources of
> > > information:
> > > 
> > > The first material to read is an excerpt from EFB 2nd ed page 81-83.
> > > Here,
> > > the authors demonstrate a typical misconception/misuse of both equivalent
> > > current dipole model and assumption of EEG source distributions (i.e.,
> > > small vs. large cortical patches). As a result, such an incorrect
> > > application leads to an implicit conclusion that there was a 5V
> > > (=5,000,000
> > > microV) source inside the brain. The authors' following concluding remark
> > > suggests there exists this known pitfall/misconception in literature
> > > reporting dipole source models in general (ouch...)
> > > 
> > > Of course, such extracellular potentials are too large by a factor of
> > > 1000
> > > or more to be physiologically realistic. However, such considerations
> > > have
> > > not prevented reports of such magical dipoles. One wonders if this
> > > explains
> > > why source magnitudes are often not reported.
> > 
> > https://urldefense.com/v3/__https://drive.google.com/open?id=1LGyydB9ZucbBG9EQoZDKAg4CEUJlAWon__;!!Mih3wA!HKOkIU0i7obnN2bi48-tFzXvjoC4GDRCU_PNDuM4JjgXO5eU64BD7_JedfcOwGzJ1sa-MaQUQsJcYI8SaWZ6jRpcvKE$
> > 
> > > The second material to read is my manuscript under review, in which I
> > > described what I believe is the correct 'scaling law' of scalp-recorded
> > > EEG
> > > signals. Please find the section "Where did the small patch model come
> > > from, and what does it miss?" in Discussion.
> > 
> > https://urldefense.com/v3/__https://www.medrxiv.org/content/10.64898/2026.01.23.26344529v1*libraryItemId=18612094__;Iw!!Mih3wA!HKOkIU0i7obnN2bi48-tFzXvjoC4GDRCU_PNDuM4JjgXO5eU64BD7_JedfcOwGzJ1sa-MaQUQsJcYI8SaWZ6Qhjxqso$
> > 
> > > I will submit a separate post about this manuscript, as this 'scaling
> > > law'
> > > is a tool for a larger aim.
> > > 
> > > I have one more thing I wanted to report here, which would make a
> > > practical
> > > (and I believe substantial) contribution to this debate. But because
> > > Komal
> > > wants to keep it a low profile until he comes up with some proof of
> > > concept, I cannot tell you what it is ha ha. I believe that this solution
> > > provides a clear answer to the question "Can EEG measure the hippocampus'
> > > at least within the limitation of the conventional synaptic dogma +
> > > volume
> > > conductor theory.
> > > 
> > > Makoto
> > > _______________________________________________
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> > > .
> > 
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