[Eeglablist] Can amygdala activity be detected on the scalp?

Rey R. Ramirez rey at sccn.ucsd.edu
Fri Dec 30 18:29:08 PST 2005


The MEG work of Andy Ioannides has shown amygdala activation on several
tasks. A simple google search should get you the right info. It is very
unlikely that these amygdala sources are electrically silent but not
magnetically silent. Keep in mind that a lot of activity in the brain is
non-phase-locked, so the ERP paradigm is not well suited to extract such
signals.

-Rey.


> That's all true, but it's worth noting that the amygdala has a lot of
> connections and interactions with other regions, such as prefrontal
> cortex, that are measured by EEG. So while you probably can't measure
> amygdala activity directly with scalp EEG, it doesn't mean that tasks
> that recruit the amygdala won't generate scalp-recorded ERPs. You just
> have to be careful about how exactly you interpret the results.
>
>
> On 12/30/05, Bradley Voytek <semiconscious at gmail.com> wrote:
>> Teresa--
>>
>> I'm sorry to say that the location of the amygdala in the anterior,
>> inferior, medial temporal lobe makes the attenuation due to distance
>> such that getting ERPs would be nearly impossible. Source localization
>> is limited because much of the signal from the amygdala is not being
>> recorded--it's on the ventral surface of the brain.
>>
>> The neurons in the amygdala are not as well aligned as in the cortex,
>> thus making dipole localization rather difficult: you'd get a lot of
>> cancelling effects due to different neuronal orientation.
>>
>> As for other limbic structures, the cingulate cortex has proven to be
>> a fairly reliable source of ERPs, so that is likely your best bet.
>> Without depth-electrodes, I just don't think you're going to get
>> signal from other limbic regions (hippocampus, hypothalamus, amygdala,
>> etc.)
>>
>> So, that's my impression.
>>
>> --brad voytek
>>
>> On 12/30/05, Teresa Wong <wongkwt at gmail.com> wrote:
>> > Dear colleagues,
>> >
>> > I would like to hear your views on whether scalp ERPs can reflect
>> activity
>> > of the amygdala.
>> > Is it possible/valid to localize dipole sources (using 128-channel
>> > recordings, emotional faces as stimuli) in subcortical brain regions,
>> limbic
>> > areas, amygdala, etc?
>> >
>> > Wishing you all a very happy and healthy 2006 with much success in
>> research!
>> >
>> > Teresa
>> > --
>> > Teresa Ka Wai Wong
>> > PhD Student
>> > Department of Psychiatry
>> > The University of Hong Kong
>> >
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>
>
> --
> Mike Cohen
> UC Davis Psychology
> Epilepsy and Psychiatry Clinics, Bonn, Germany
> http://www.DynamicMemoryLab.org/mcohen
>
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-- 
Rey R. Ramirez, Ph.D.
Swartz Center for Computational Neuroscience
Institute for Neural Computation
University of California, San Diego
La Jolla, CA, USA
tel: (858) 458-1927 ext. 18
e-mail: rey at sccn.ucsd.edu
web: http://sccn.ucsd.edu



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