[Eeglablist] Source localization and hippocanpus

[Joseph Dien]

We made a good case that the Feedback Negativity (FN) originates from 
the striatum (Foti, Weinber, Dien, & Hajcak, 2011, 2011). It's not a 
claim to be made lightly.  The cortex is a strong candidate as far-field 
generators because it is rich on pyramidal neurons, which have 
asymmetrical dendrites and tend to be oriented in the same direction, 
but that does not mean it is the only possible source.  To make a case 
for a subcortical generator, you have to be able to demonstrate 
convergent validity with data from methods like intracranial EEG 
recordings.  See our papers for arguments and references.

The hippocampus, on the other hand, is the classic example of a 
structure that is likely to be a closed field generator because it is in 
the form of a tube, wherein the field from a given neuron is likely to 
be canceled out by the field from a neuron pointing the opposite 
direction on the other side of the tube, resulting in a net zero voltage 
field when measured from outside the tube.  No amount of electrodes or 
computational sophistication is going to help with that.  Of course, 
it's all complicated because the entire tube isn't necessarily equally 
active.  Also, the adjoining parahippocampal cortex isn't a tube.  There 
seems to be a lot of discussion going on right now about what can be 
measured.  But yeah, making a plausible claim for a hippocampal 
generator would require very strong evidence.  As John says, it's easy 
to put a equivalent dipole in the hippocampal region and get non-zero 
results, so not strong evidence by itself.  But I'd also be wary of 
making sweeping generalizations.

Joe

Foti, D., Weinberg, A., Dien, J., & Hajcak, G. (2011). Event-related 
potential activity in the basal ganglia differentiates rewards from 
nonrewards: Temporospatial principal components analysis and source 
localization of the feedback negativity. /Hum Brain Mapp/, /32/(12), 
2207–2216. https://urldefense.com/v3/__https://doi.org/10.1002/hbm.21182__;!!Mih3wA!F6lfB756tGdH_QFKwL5mIWetNG672s_aafnqgyt9T8wO7nrcuWuqfT_GvDz4sGND_j85H6f_kjzDtWSplqI$ 

Foti, D., Weinberg, A., Dien, J., & Hajcak, G. (2011). Event-related 
potential activity in the basal ganglia differentiates rewards from 
nonrewards: Response to commentary. /Hum Brain Mapp/, /32/(12), 
2267–2269. https://urldefense.com/v3/__https://doi.org/10.1002/hbm.21357__;!!Mih3wA!F6lfB756tGdH_QFKwL5mIWetNG672s_aafnqgyt9T8wO7nrcuWuqfT_GvDz4sGND_j85H6f_kjzDCIoX_BY$ 

On 1/14/26 18:52, Richards, John via eeglablist wrote:
> The hippocampus, caudate, putamen, amygdala, sometimes are classified with "cortex" as gray matter and people might try to do source analysis.  However, only the cortex has the perpendicular pyramidal structure that conducts current to the scalp, and the "subcortical" brain areas do not have the correct structure to generate current on the scalp.  If you put source locations in these areas and do source analysis you will get "something", likely due to activity in other brain areas, noise, or other non-neuron activity.
>
> I think that a couple of the "internal" cortex ROIs, like the insula, have the cortex structure to generate current.  But its possible that it cannot be measured because the area is relatively far from the scalp and any current would be small.
>
> John
>
> ***********************************************
> John E. Richards
> Carolina Distinguished Professor
> Department of Psychology
> University of South Carolina
> Columbia, SC  29208
> Dept Phone: 803 777 2079
> Fax: 803 777 9558
> Email:richards-john at sc.edu
> https://urldefense.com/v3/__https://jerlab.sc.edu/__;!!Mih3wA!ETNTEAJ6TN4Jy-leSX_wNE4oEjcJRGEvhvPv9VUow0FLXB7TonoRBJczbLfGx7O-lhiZ8zLs-rOV6e3nqjWwi01tM5J3lQ$ 
> ***********************************************
>
> -----Original Message-----
> From: eeglablist<eeglablist-bounces at sccn.ucsd.edu> On Behalf Of Cedric Cannard via eeglablist
> Sent: Wednesday, January 14, 2026 3:43 PM
> To: EEGLAB List<eeglablist at sccn.ucsd.edu>
> Subject: [Eeglablist] Source localization and hippocanpus
>
> Hi everyone,
>
> My understanding is that it is impossible to reliably pick up activity from the hippocampus when doing any form of source localization/reconstruction from 64 channels EEG data (or more?). Is that still correct or are there solutions I am not aware of?
>
> Thanks,
>
> Cedric
>
> Sent from [Proton Mail](https://urldefense.com/v3/__https://proton.me/mail/home__;!!Mih3wA!H46-4iFcBgfgy3ULwhOg2lRNA9hx14UKJ51O7YOQGv_qxIo73r6XogOPtdkKmYkAhgU-ZAxb7wodi1BOqhUQ1w$ ) for iOS.
> _______________________________________________
> To unsubscribe, send an empty email toeeglablist-unsubscribe at sccn.ucsd.edu or visithttps://sccn.ucsd.edu/mailman/listinfo/eeglablist .
> _______________________________________________
> To unsubscribe, send an empty email toeeglablist-unsubscribe at sccn.ucsd.edu or visithttps://sccn.ucsd.edu/mailman/listinfo/eeglablist.

-- 
--------------------------------------------------------------------------------

Joseph Dien, PhD
Senior Research Scientist
Department of Human Development and Quantitative Methodology
University of Maryland, College Park
E-mail:jdien at umd.edu
https://urldefense.com/v3/__http://joedien.com__;!!Mih3wA!F6lfB756tGdH_QFKwL5mIWetNG672s_aafnqgyt9T8wO7nrcuWuqfT_GvDz4sGND_j85H6f_kjzDInHV-ww$