[Eeglablist] Different clusters within thalamus?

[Scott Makeig]

This recent paper<http://link.springer.com/article/10.1007/s10548-012-0274-6/fulltext.html>by
Zeynep Akalin Acar finds that mis-specification of the skull
conductivity ratio (versus scalp or brain) may drive the equivalent dipoles
deeper than they actually are.  This is a variable for which there is
currently no easy/best method of measurement.  Therefore, the radial depth
of equivalent dipole localizations may be their least well-defined
dimension.  Before accepting a thalamic localization for an equivalent
dipole, I would want to thoroughly test the influence of the head model
being used on the depth of the imputed source location.

Scott

On Thu, Mar 28, 2013 at 2:14 AM, Arnaud Delorme <arno at ucsd.edu> wrote:

> Dear Aleksandra,
>
> the Thalamus as all subcortical structure most likely has a minor effect
> on scalp EEG (because it is a node, if all neurons are active at the same
> time, their net potential is null). A perfect spherical domain of synchrony
> cannot be seen on the scalp.
>
> Now the interaction between the thalamus and the cortex is what might be
> seen. I guess it would be seen as ICA components with a cortical location.
>
> Best,
>
> Arno
>
> On 22 Mar 2013, at 17:48, Makoto Miyakoshi wrote:
>
> Dear Aleksandra and Tom,
>
> > However Tom's email indicates that the source analysis model used in EEG
> lab is not adequate for localising sources in deeper structures, or I got
> it wrong?
>
> My naive thought is that thalamus is involved in alpha rhythm but that
> does not mean it project it to the scalp. It is one of nodes of network
> that drives the occipital cortical patches to oscillate in alpha. Let me
> know if you find more information about it.
>
> Tom's input is informative as usual. Thanks.
>
> Makoto
>
> 2013/3/19 Aleksandra Vuckovic <Aleksandra.Vuckovic at glasgow.ac.uk>
>
>>  My modest understanding is that thalamus generates rhythmic oscillatory
>>  activity and is one of the generators of the alpha rhythm. I taught
>> therefore that it should not be surprising that some ICs are located in
>> thalamus. However Tom's email indicates that the source analysis model used
>> in EEG lab is not adequate for localising sources in deeper structures,
>> or I got it wrong?
>> Thanks,
>> Aleksandra
>>
>>  ------------------------------
>> *From:* Makoto Miyakoshi [mmiyakoshi at ucsd.edu]
>> *Sent:* 19 March 2013 17:14
>> *To:* Aleksandra Vuckovic
>> *Cc:* EEGLAB List
>>
>> *Subject:* Re: [Eeglablist] Different clusters within thalamus?
>>
>>  Dear Aleksandra,
>>
>>  >Even some that I see consistently across subjects?
>>
>> Consistency across subjects does not increase the possibility that the
>> ICs are really located in or near thalamus, unless you are using the
>> combination of digitized channel locations, subject's MRI head image, and
>> Zeynep Akalin Acar's NFT...
>>
>>  To generate a dipole, neuron arrays should have a specific pattern. I'm
>> not sure if thalamus also has this pattern. It's a matter of
>> cytoarchitecture, so you may want to read papers about electrophysiological
>> mechanism of generating EEG. I don't know much about it, so if you find
>> something interesting please share with us.
>>
>>  Makoto
>>
>> 2013/3/19 Aleksandra Vuckovic <Aleksandra.Vuckovic at glasgow.ac.uk>
>>
>>>  Hi
>>> does it mean that these sources are not of a physiological origin (EEG
>>> related)? Even some that I see consistently across subjects?
>>> Many thanks,
>>> Aleksandra
>>>
>>>  ------------------------------
>>> *From:* Makoto Miyakoshi [mmiyakoshi at ucsd.edu]
>>> *Sent:* 19 March 2013 00:27
>>> *To:* Aleksandra Vuckovic
>>> *Cc:* eeglablist at sccn.ucsd.edu
>>> *Subject:* Re: [Eeglablist] Different clusters within thalamus?
>>>
>>>   Dear Aleksandra,
>>>
>>>  Independent components located in or near thalamus should be mostly
>>> due to localisation error in dipole fitting (forward model error/inverse
>>> solution error/channel location error/...etc). We see it often though :-)
>>>
>>>  Makoto
>>>
>>> 2013/3/16 Aleksandra Vuckovic <Aleksandra.Vuckovic at glasgow.ac.uk>
>>>
>>>>   Hi
>>>> has anybody tried to cluster components at different locations within
>>>> thalamus and according to which criteria?
>>>> Many thanks!
>>>>  Aleksandra
>>>>
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>>>
>>>
>>>
>>>  --
>>> Makoto Miyakoshi
>>> JSPS Postdoctral Fellow for Research Abroad
>>> Swartz Center for Computational Neuroscience
>>> Institute for Neural Computation, University of California San Diego
>>>
>>
>>
>>
>>  --
>> Makoto Miyakoshi
>> JSPS Postdoctral Fellow for Research Abroad
>> Swartz Center for Computational Neuroscience
>> Institute for Neural Computation, University of California San Diego
>>
>
>
>
> --
> Makoto Miyakoshi
> JSPS Postdoctral Fellow for Research Abroad
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
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-- 
Scott Makeig, Research Scientist and Director, Swartz Center for
Computational Neuroscience, Institute for Neural Computation, University of
California San Diego, La Jolla CA 92093-0559, http://sccn.ucsd.edu/~scott
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