[Eeglablist] When to perform re-reference?

[Brian Scally]

Hi there,

I have been following the discussion. So it is recommended to re-reference
to average after removing channels/epochs and right before running
ICA. Suppose I plan on running ICA twice: the first time to identify epochs
that are affected by improbable components, after which the epochs will be
removed. The second time would be to remove actual components. Do I need to
re-reference before the first, or will before the second suffice?

Cheers,
Brian


On 19 June 2014 00:56, Makoto Miyakoshi <mmiyakoshi at ucsd.edu> wrote:

> yes.
>
>
> On Wed, Jun 18, 2014 at 3:45 PM, Jerry Zhu <jerryzhu at siu.edu> wrote:
>
>> Hi Makoto,
>> Thank you again for your reply.
>>
>> Did you mean "averaging AFTER removing bad epoches" in your sentence "you
>> should apply average referencing AFTER removing bad channels."?
>>
>> So here are my processing:
>> 1) re-reference  (from Cz to average in my case)
>> 2) remove bad epoches
>> 3) interpolate bad channels
>> 4) ICA
>>
>> Sounds like you would recommend the order: 2143?
>>
>> Looking forward to your and others inputs!
>> Thanks all!
>> Jerry
>>
>> --
>> Jian Zhu, M.A.
>> Brain and Cognitive Sciences
>> Department of Psychology
>> Southern Illinois University Carbondale
>> Web: http://zhupsy.com
>>
>> We have two halves in the brain: left and right. Nothing is right in the
>> left. Nothing is left in the right.
>>
>>
>> On Wed, Jun 18, 2014 at 1:38 PM, Makoto Miyakoshi <mmiyakoshi at ucsd.edu>
>> wrote:
>>
>>> Dear Jason,
>>>
>>> I remember you said that average reference should be applied before ICA,
>>> but I did not understand exactly why. Could you comment on this?
>>>
>>> Jerry, you should apply average referencing AFTER removing bad channels.
>>>
>>> I don't think it makes big differences between average referencing
>>> before or after interpolation. However we don't necessarily recommend
>>> interpolation before ICA.
>>>
>>> Makoto
>>>
>>>
>>> On Tue, Jun 17, 2014 at 12:20 PM, Jerry Zhu <jerryzhu at siu.edu> wrote:
>>>
>>>> Hi all,
>>>> At which stage do you re-reference your data? It was suggested do
>>>> re-ref before ICA (
>>>> http://sccn.ucsd.edu/pipermail/eeglablist/2011/003795.html). How about
>>>> re-ref before/after bad epochs rejection and bad channel interpolation? The
>>>> note here  (
>>>> ftp://ftp.egi.com/pub/documentation/technotes/SplineInterpolation.pdf)
>>>> suggests after interpolation. ("Since the interpolated potentials can be
>>>> used to better approximate the average reference (Junghofer et al., 1999),
>>>> it may be somewhat advantageous to compute the interpolated potentials
>>>> directly from the measured data, in which case the voltages below are best
>>>> thought of as referring to these measured potentials")
>>>>
>>>> What is your experience? Thanks for your sharing and suggestions!
>>>>
>>>> Jerry
>>>> --
>>>> Jian Zhu, M.A.
>>>> Brain and Cognitive Sciences
>>>> Department of Psychology
>>>> Southern Illinois University Carbondale
>>>> Web: http://zhupsy.com
>>>>
>>>> We have two halves in the brain: left and right. Nothing is right in
>>>> the left. Nothing is left in the right.
>>>>
>>>> _______________________________________________
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>>>
>>>
>>>
>>> --
>>> Makoto Miyakoshi
>>> Swartz Center for Computational Neuroscience
>>> Institute for Neural Computation, University of California San Diego
>>>
>>
>>
>
>
> --
> Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
>
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-- 
Brian Scally
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