[Mne_analysis] Maxwell Filter and Projections

[dgw]

On Fri, Mar 25, 2016 at 1:39 PM, Sam Zorowitz <szorowi1 at gmail.com> wrote:
> Absolutely. The short of it is that we were running into some issues with
> the Maxwell filter function, such that the SVD will not converge for certain
> buffers if there is an abundance of noise. As such, we were performing epoch
> rejections on the raw to determine time periods with high amounts of noise;
> removing these time periods from the raw; and passing the resulting raw
> object to Maxwell filter.
>

Sam, the easier way to do this, would be to find windows of noise, and feed
those to the call to maxfilter (using -skip, or the mne-python equivalent).

Honestly, there might be a much bigger issue lurking somewhere... Your
data shouldn't have noise that causes maxfilter not to work (we have an
incredible shielded room, and I don't think you should ever have noise issues
that maxfilter can't handle.

hth
d

> The process above would yield the following processing steps:
>
> Perform epoch rejections
> Crop raw data and re-stitch good
> Maxwell filter data
> Save filtered raw data
> Make EOG/ECG projections
> Perform epoch rejections
> Save epochs
>
> We were wondering if we could skip a few steps by making the EOG/ECG
> projections ahead of time. That way we wouldn't need to re-epoch and save
> out an additional raw file. Instead we could make and apply the projections
> before Step (1). Does that make sense?
>
> Thanks!
> -Sam
>
>
> On Fri, Mar 25, 2016 at 11:06 AM, dgw <dgwakeman at gmail.com> wrote:
>>
>> Hi Sam,
>>
>> Maybe the place to start is why would you want to do this?
>>
>> d
>>
>> On Fri, Mar 25, 2016 at 10:02 AM, Sam Zorowitz <szorowi1 at gmail.com> wrote:
>> > Hi all,
>> >
>> > Hopefully a quick question: Is there any reason why projections should
>> > not
>> > be applied in advance of using the Maxwell filter? I understand that
>> > doing
>> > so results in error for the Neuromag MaxFilter program, as well as the
>> > newly
>> > implemented maxwell_filter function in mne-python. Any reason for this?
>> >
>> > Thanks!
>> > -Sam
>> >
>> > --------------------------------------------------
>> >
>> > Sam Zorowitz
>> >
>> > Clinical Research Coordinator
>> >
>> > Division of Neurotherapeutics
>> >
>> > Department of Psychiatry: Neurosciences
>> >
>> > Massachusetts General Hospital
>> >
>> >
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