Command: PrePro, FilterNetFile, FiltNeuroscanFiles, TransNetGeoHist, NeuroScanToEgis, TransMsiContSess, CalcAutoEditMat, CalcAutoEditMEGMat
Filtering and segmentation can be done manually, using scripts like
'Batch.m' that call 'FilterNetFile', or, or by using 'PrePro' user
interface (under construction).
Filtering and
segmentation using
PrePro (under construction)
PrePro, when started, is disabled, and waits for you to open a
data file, or to load a batchfile containing paths of datafiles.
Datafiles must have the same format (EGI, Neuroscan or BTI) and the
same sampling rate and the same number of channels. After succesfully
loading a file, the number of channels and the sampling rate are
displayed in the upper right corner.
Filters: After
loading a file, you can activate and configure highpass, lowpass and
stopband filters by enabling their radio-buttons. Initially you have to
configure every filter, that you enable.
Segmentation: By
entering numbers in the PreTrig and PostTrig boxes, you can define how
many points will be taken before each event and how many after.
Events: The default behaviour
in PrePro segmets your data for every kind of event it encounters. If
you do not like this, you can activate the 'use only'-box and enter
numbers, corresponding the trigger values that you wish to use. All
others will be ignored.
Artifact
detection: PrePro automatically chooses
the entire extracted intervall, to calculate statistical parameters,
that afterwards can be used for artifact detection. If you wish to use
only a certain part of the intervall for this purpose, you can define
separate PreTrig- and PostTrig-points for artifact detection. Generally
a longer intervall is more likely to contain artifacts, thus leading to
less good trials.
Amplifier
calibration: This options so far is only available for EGI data.
Neuroscan data is analyzed presuming all GAINS to be 1 and all ZEROS to
be 0. For EGI-data, you can one specific set of GAIN and ZEROs, that
will be used for all files, or have PrePro search for a GAIN and ZERO
for every data file in the batch separately. This is done simply by
using the filename, so be sure, to have consistent filenaming.
Miscellaneous: The options 'change RAW
to TAW' and 'remove additional AR-channels' again only apply to
EGI data, and normally can be left active. The option 'skip step if
file exists' lets you avoid repeating one step if it already has been
performed and procuded a result file. 'One step for all' vs. 'All
steps for one' refers only to batch processing, and decides
wether PrePro will perform one step (for instance the segmentation) for
all files in the batch before going one with the next step. Otherwise,
all steps will be performed for one file, and then all steps for the
next etc. The latter is generelly preferable for long batches, that you
do not want to crash half way through. Thus, if a problem occurs on one
file, PrePro will still get the other files right.
All settings including the filematrix can be saved and loaded using the
menu \File\Default File.
Manual filtering and segmentation
Generally, filtering a raw-data-file saves the filtered data in a new
file, adding filter-dependant characters to the filename. A lowpass
40Hz filter, for instance, transform the file '01.run1.taw' to 01.run1.fl40.taw'.