2021-02-02T16:14:49Z

Mateusz: Created page with "{{BESAInfobox |title = Module information |module = BESA Research Standard or higher |version = 6.1 or higher }} In EEG/MEG data analysis frequency filtration is one of the m..."

{{BESAInfobox
|title = Module information
|module = BESA Research Standard or higher
|version = 6.1 or higher
}}

In EEG/MEG data analysis frequency filtration is one of the most basic and at the same time important operations. In BESA Research filtration is implemented as a linear operation so it is interchangeable in the processing pipeline - it can be changed at every processing step in almost all situations. There are however some moments that filtration cannot be applied in a linear manner - i.e. averaging. In general, we recommend not apply filtration during such types of operations as it can be replied afterward. You will be prompted by the application if you encounter such a moment in data analysis:

[[File:Filter_notification.jpg]]

Also at some stages of the data processing, the filtration is of major importance, therefore we made it more accessible and you can easily redefine it. Please have a look at the table below:
{| class="wikitable" style="text-align:center;"
! style="font-weight: bold;" | Filter type
! style="font-weight: bold;" | Review window
! style="font-weight: bold;" | Search Average View
! style="font-weight: bold;" | Averaged buffer
! style="font-weight: bold;" | FFT
! style="font-weight: bold;" | lienear corelation/regression
! style="font-weight: bold;" | Combine Conditions
! style="font-weight: bold;" | ERP
! style="font-weight: bold;" | Coherence
! style="font-weight: bold;" | Time Frequency plot (single click)
! style="font-weight: bold;" | TopViewer
! style="font-weight: bold;" | Source Analysis
|-
| style="font-weight: bold;" | Low/High pass
| style="background: #F2D16B" |Main
| style="background: repeating-linear-gradient(45deg, #F2D16B,#F2D16B 10px, #BA9588 10px, #BA9588 20px);"| Main / can be redefine to default values(2-35Hz)
| style="background: #BA9588" |as used during buffer creation
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| None
| style="background: #6BCFF2" |ERP
| style="background: #6BCFF2" |ERP
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| style="background: #CFF26B" |SA
|-
| style="font-weight: bold;" | Notch
| style="background: #F2D16B" |Main
| style="background: repeating-linear-gradient(45deg, #F2D16B,#F2D16B 10px, #BA9588 10px, #BA9588 20px);"| Main / can be redefine to default values(2-35Hz)
| style="background: #BA9588" |as used during buffer creation
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| None
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
|-
| style="font-weight: bold;" | Bandpass
| style="background: #F2D16B" |Main
| style="background: repeating-linear-gradient(45deg, #F2D16B,#F2D16B 10px, #BA9588 10px, #BA9588 20px);"| Main / can be redefine to default values(2-35Hz)
| style="background: #BA9588" |as used during buffer creation
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| None
| style="background: #6BCFF2" |ERP
| style="background: #6BCFF2" |ERP
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
|-
| style="font-weight: bold;" | Polygraphic
| style="background: #F2D16B" |Main*
| style="background: repeating-linear-gradient(45deg, #F2D16B,#F2D16B 10px, #BA9588 10px, #BA9588 20px);"| Main* / can be redefine to default values(2-35Hz)
| style="background: #BA9588" |as used during buffer creation
| style="background: #F2D16B" |Main*
| style="background: #F2D16B" |Main*
| None
| style="background: #F2D16B" |Main*
| style="background: #F2D16B" |Main*
| style="background: #F2D16B" |Main*
| style="background: #F2D16B" |Main*
| n.a.
|-
| style="font-weight: bold;" | artifact correction
| style="background: #F2D16B" |Main
| style="background: repeating-linear-gradient(45deg, #F2D16B,#F2D16B 10px, #BA9588 10px, #BA9588 20px);"| Main / can be redefine to default values(2-35Hz)
| style="background: #BA9588" |as used during buffer creation
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| style="background: #6BCFF2" |ERP
| style="background: #6BCFF2" |ERP
| style="background: #F2D16B" |Main
| style="background: #F2D16B" |Main
| style="background: repeating-linear-gradient(45deg, #F2D16B,#F2D16B 10px, #CFF26B 10px,#CFF26B 20px);"| Main/SA
|}

==Main settings==
The main setting for artifact correction can be set using '''EdF''' or menu entry '''Filters/Edit Filter Settings'''...

[[File:filter_main.jpg]]

==Specific ERP settings==
The ERP filter settings can be set during paradigm definition. Note that there are two different settings - for artifact scan and for averaging

[[File:filter_ERP.jpg]]

==Specific Source Analysis settings==
For source analysis (SA), if you press ''''ESI/MSI''' button on the toolbar ribbon ''Main'' filter settings will be used.) Filters for SA can be set during sending a block of data to Source Analysis (right-click on the highlighted block and select '''Source Analysis''').

[[File:filter_SA.jpg]]

==Notch filter==
Note that because of its generic nature - power line artifact removal - notch filter is treated differently. The notch filter value populates from ''Main'' setting to all subsequent applications.

==Bandpass filter==
Bandpass filter is complementary to high/low pass filter combination. For convenience, it is treated differently and also populates to all subsequent applications from ''Main'' setting.

==Polygraphic filter==
Polygraphic channels are filtered using Main settings. Note that there are additional settings that can be applied to the polygraphic filter accessible via '''Filters/Polygraphic/Additional Chans...'''

[[File:filter_poly.jpg]]

[[Category:Preprocessing]]

File:Filter poly.jpg

2021-02-02T16:13:20Z

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