Maxfilter - Meg Wiki

Upload page content

You can upload content for the page named below. If you change the page name, you can also upload content for another page. If the page name is empty, we derive the page name from the file name.

File to load page content from
Page name
Comment
Type the odd letters out: scieNce GATHeRS knowledge fAster tHAN SOCIeTY GATHErS wisdom

location: Maxfilter

mrclogo.gif

MaxFilter

Background

A common first step in analysing your data is to pre-processing them using the Maxfilter program. This Neuromag sofware implements "Signal-Space Separation" (SSS), which is a clever mathematical way to separate magnetic signals coming from within the brain (or more precisely, a sphere within the sensors) from those coming from outside the brain (or more precisely, from outside a sphere outside the sensors). There are several technical papers on Maxfilter theory and applications e.g. this and this.

Maxfilter is helpful for 1) removing noise originating from sources outside the sensor array, 2) detecting bad channels, 3) realigning (interpolating) data after movement (provided you have used continuous HPI) and 4) moving the data to a standard space (e.g, across subjects).

Maxfilter use at the CBU

Our latest Maxfilter version is Maxfilter 2.2.14 (but the previous version 2.2.12 is also in use).

The following example will apply Maxfilter including Signal Space Separation (SSS), its temporal extension (ST), and movement compensation.

maxfilter-2.2.14  -f input_file.fif  -o output_file.fif  -st  -origin 0 0 45  -frame head  -autobad on  -movecomp  -cal /neuro/databases_triux/sss/sss_cal.dat -ctc /neuro/databases_triux/ctc/ct_sparse.fif

If you are using data from our previous Vectorview machine, the last two options should be

-cal /neuro/databases_vectorview/sss/sss_cal.dat -ctc /neuro/databases_vectorview/ctc/ct_sparse.fif

For more information on these and other options, see the Maxfilter 2.2 manual

Signal Space Separation is also implemented in MNE-Python.

Diagnostics

You can get information about movement parameters using these scripts to analyse maxfilter output.

See also the archives of this email list (www.jiscmail.ac.uk/lists/NEUROMEG.html‎) which you may also want to join to hear about latest maxfilter updates.

Other related Wiki pages: