[Eeglablist] Low density system questions

[Fran Copelli]

Thanks Scott, that's helpful. Are there any guidelines for
removing/interpolating components for low density systems?

Fran

SMART Lab, Psychology Department


On Sat, May 2, 2020 at 5:11 PM Scott Makeig <smakeig at ucsd.edu> wrote:

> Usually the 'CNS' reference electrode is (in Biosemi) part of a CNS-DRL
> pair. If it is here a single reference electrode then you should'nt need to
> rereference unless you want to do source analysis. But remember that
> electrodes placed near the reference channel will record very little
> signal, because they and the reference will have nearly the same signal,
> and each EEG channel is the difference between two (or more) electrodes.
>
> Scott
>
> On Sat, May 2, 2020 at 5:04 PM Fran Copelli <fcopelli at ryerson.ca> wrote:
>
>> Hi Scott — thanks for your reply — but the system is actually the
>> Starstim 20 from Neuroelectrics; we are using 18 scalp channels following a
>> 1020 system layout. I’m not sure if the same rule applies to this system—
>> can you advise?
>>
>>
>> On May 2, 2020, at 4:45 PM, Scott Makeig <smakeig at gmail.com> wrote:
>>
>> 
>> If you are using a Biosemi system (with CMS-DRL electrodes) then you must
>> re-reference to eliminate a <=40 dB noise contamination (see the Biosemi
>> website). You may reference as you wish -- using average reference is
>> typically a good choice.
>>
>> Scott Makeig
>>
>> On Sat, May 2, 2020 at 8:40 AM Fran Copelli <fcopelli at ryerson.ca> wrote:
>>
>>> Dear list,
>>>
>>> My colleague is collecting data using a low density (18 channel) system.
>>> With so few channels, what are the guidelines regarding a) whether noisy
>>> channels should be deleted or interpolated and b) what is the maximum
>>> value
>>> to remove and still have interpretable data.
>>>
>>> My second question is regarding referencing. The manual for the system
>>> suggests that all data is referenced to CMS. Should we be rereferencing
>>> to
>>> another channel/to the average? Is average referencing suitable for such
>>> a
>>> low density system? Note that there are no mastoids to reference, only
>>> scalp and eye channels.
>>>
>>>
>>> Thanks very much and looking forward to hearing any suggestions,
>>>
>>> Fran
>>>
>>> Fran
>>>
>>> SMART Lab, Psychology Department
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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
>>
>>
>
> --
> Scott Makeig, Research Scientist and Director, Swartz Center for
> Computational Neuroscience, Institute for Neural Computation, University of
> California San Diego, La Jolla CA 92093-0961, http://sccn.ucsd.edu/~scott
>