xeog - Electrooculogram Epoch Classification

Contents

Synopsis


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EEP 3.1  Max-Planck-Institute of Cognitive Neuroscience 1996-99
xeog 3.21   (OSF1 V4.0 alpha)                 Wed Sep 15 13:30:16 1999
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classification mode:
  xeog <cnt> [<cfg>] [<trg in>] [<rej in>] [<cls in>] [-a <average cfg>]
rejection mode:
  xeog -r <cnt> [<cfg>] [<trg in>] [<rej in>] -a <average cfg>


Generals

xeog offers two kinds of manual trial classification/selection according to EOG activity: There are two types of epochs one have to classify:
EOG Events
signal epochs highlighted by the cntreject utility; a represantative subset of blink and move epochs ("prototypes") has to be selected from the events offered here; the propagation factor sets are calculated from this prototype selection; this step is not needed in rejection mode
Trials
the parts of the EEG record one is going to use for averaging; one have to specify a correction method for each trial; this can be one of

uncorrected ("U")
use this trial "as is"
blink("B")
use the blink propagation factor set for the EOG compensation
move("M")
use the move propagation factor set for the EOG compensation
reject("R")
don't use this trial
In rejection mode you can choose only "U" or "R".
The xeog results in classification mode are In rejection mode there is only one result: Refer also to the prepared scripts in the demo/classify directory.

Requirements

xeog uses the general cnt-file Viewer xcnt. So you should simply try to view the raw data file at very first.

Second, you are required to have a valid xeog configuration file.

Finally you need some data input beside the EEG record and the configuration:

a trigger file which is used for
a rejection file which is used for
an EOG event classification file (.cls, optional) which is used for
the cntaverage configuration file which is used for

Configuration

Configuration File

The xeog configuration contains colors, sizes, scalings and channel selections for the data visualization and the EOG artifact compensation algorithm. The rejection mode usually needs an other setup than the classification mode - less channels, more epochs in the display. Accordingly, there are two example files in the sample configuration directory: xeog.cfg and xreject.cfg.

Resources

app-defaults/Xeog

User Interface

Menu Bar

File Menu
"Save..." functions for the results you can yield from xeog; note that you can load data only via command line. The exit function will display a warning message if unsaved classifications are found.
Classification Menu
Calculate Propagation Factors
calculates the propagation factors from the current prototype classification; a error message is displayed if no prototypes are available

be careful to keep your current classification, the saved classification, the current factors and the saved factors in a consistent state - so the best is to select the prototypes, calc factors, save both, forget it, and deal with the trials only after this - don't hop around

Sync Trials with Rejections
check the trial rejection windows for rejections and classify the trial "r" if rejections are found and "u" if not; this is done at startup by default if no trial classification is loadable

Sync Trials with Prototypes
check the trial average windows for common time ranges with prototypes; set the trial classification to this prototypes; if a trial contains more then one prototype, the latter one is used

Set Rejected Trials to Blink
nearly all rejections in trials are caused by eye blinks, so it may save some clicking if you start with blinks and remove the (few) non-blinks from this class

Set Unclassified Trials to Move
cntreject usually marks only "large" EOG events. You will find a lot of your trials infected by EOG but not marked. You can either
Display Menu/Options Menu
Selects the data to be displayed and how they are displayed; no data changes; remember that you have the xcnt raw data viewer beside xeog if you need a more facilitated display.

The Average Preview contains the averaged ERP's for the channels from the [preview channels] or [eog channels] cfg section. The first calculation (started after selecting a condition toggle) may take a while. Once the averages are calculated they are updated after each classification change.

Diagram Area

You can (and have to) adjust and classify your epochs manually here. If you prefer the keyboard to the mouse you can move the drawing cursor using cursor, PgUp, PgDown keys and classify epochs pressing the matching letters. The "return" key synchronizes xcnt to the current epoch. Adjusting prototype epoch limits is possible with the pointer only.

The pointer classification methods should need no explanations - click around a little.

In rejection mode there are no classification buttons available. The rejection is done by pointer clicks into the drawing and is indicated by dotted lines.

Control and Status Area

The Scaling group allows some basic diagram adaptions, the Window group gives you an impression where your displayed epochs are in the list (how much work is left). The First: field acceps an epoch index, a condition label string or a condition shortcut string. The Status group shows more detailed informations about the data you process in xeog.

Classification Hints


EEP 3.1 - MPI/ANT(eeprobe@ant-software.nl), 15.09.1999
Copyright © 1996-99 Max-Planck-Institute of Cognitive Neuroscience. All rights reserved.
emplate (evaluated in PostScript only) The default label position is (0;0) (lower-left corner of the diagram). The x-offset is fieldwidth, the y-offset is fieldheight, and the alignment is top-right. This means that the label appears in the upper right corner of the diagram field.

Axis division values are not permitted to cover axis lines and the spacing between division lines must be larger than 3 * division linewidth. Otherwise, nothing is drawn.

The probability axis of the semilogarithmic t-ttest diagram is hard-coded (min:1 max:0.001). Linestyle parameters are inherited from time/ampl axes. Divisions lines (ttest_div) are possible with pos only, not with step.

Map Templates

Example

[map template]
name         default
field        width:60 palette:bluered
time_axis    unit:s  scale:1 fmt:"&C: %.3f .. %.3f %s" tsize:2 ty:5
ampl_axis    unit:uV scale:1 min:-5.5 max:5.5
ampl_div     step:1 lw:0.2
outline      lw:0.2 
sensors      size:1 
legend       height:5 width:40 fmt:"%+.1f"

Reference

field
  width:    width/height of the square covering all map parts (in mm)
  palette:  color palette for amplitude (z-axis) encoding
            (the name of an own map palette or one of
             the predifined palettes "bluered","grey","mapview",
             "spectrum")
  sel:      file selection
  mesh:     for debugging; toggle drawing 0f the triangle mesh (0 or 1)
time_axis
  unit:   time unit string ("s" or "ms")
  scale:  size of the unit above in terms of xavr base units (seconds)
  fmt:    format string for map label output
          (printf placeholders for tmin, tmax and the time axis unit and
          ERP attribute placeholders)
  t...:   textstyle parameters for the label string
          (text origin is the map object position)
ampl_axis
  unit:   amplitude unit string ("uV" or "fT", "z" enables 
          z-standardization)
  scale:  size of the unit above in terms of average data units
  min:    amplitude value assigned to the lower end of the color scale
  max:    amplitude value assigned to the upper end of the color scale
ampl_div
  step:   the amplitude range represented by one color
  l...:   linestyle parameters for the iso... lines 
          (0 means no isolines)
outline
  l...:   linestyle parameters for the outline polygon
sensors
  size:   diameter of the dot which represents the sensor pos. (in mm)
  fmt:    printf format string for sensor label plot ("%s")
  t...:   textstyle parameters for sensor label plot
          (text origin is sensor position)
  l...:   linestyle parameters for sensor dot plot
legend
  height: height of the color scale legend
  width:  width of the color scale legend
  fmt:    printf format string for min/max amplitude values ("%.1f")
  t...:   textstyle parameters for min/max amplitude values

Map Palette

Description

A [map palette] section describes a sequence of colors which can be used in [map template] sections.

The first line defines the name of the palette. This line is optional. A palette without a name is used for all maps.

It is followed by a list of <color> [<coordinate>] pairs, where <color> can be any valid X color specification and the optional <coordinate> is the relative position of the given color (0.0 - minimum, 1.0 - maximum) in the generated palettes.

The actual palette colors are computed by linear interpolation of the red/green/blue components between these given supporting points. (Eventually, your display hardware gives you only approximations of the requested colors. You need to look at the final PostScript output then.)

Examples

[map palette]
name strange
rgb:00/f0/00  0.0
rgb:00/00/f0  0.2
rgb:00/00/ff  1.0

[map palette]
name bluered
blue
white
red

Legend Template

The [legend template] section instructs xavr to create line and text objects which together form a legend. This way you have a dynamic legend which explains the current view without any interaction. This can be disabled in the Options menu.

Example

[legend template]
headline    fmt:"Legend:" x:230 y:100 tsize:4.5
avr_entry   fmt:"&C (n=&N)"           tsize:3.5 len:6
diff_entry  fmt:"&s4 &c - &S4 &C"     tsize:3.5 len:6

Reference

headline
  fmt:    legend headline string
  x:      position of the legend headline text
  y:      position of the legend headline text
  dh:     horizontal distance between entries (in mm), default:0
  dy:     vertical distance between entries (in mm), default:-1.4*fontsize
  t...:   textstyle parameters for the legend strings
avr_entry/diff_entry
  fmt:    legend format string, subject to 
          ERP attribute expansion
  len:    length of the sample line segment (in mm)
  t...:   textstyle parameters for the legend strings

Style Template

The [style template] assigns individual linestyle parameters to selected trace lines in time series diagrams. It overrides the trace_line parameters in the [global defaults] section and the color which is stored in the avr files. It is overridden by the interactive trace style settings.

Example

[style template]
trace  sel:"&C=rare"     lcol:red  ldash:dotted
trace  sel:"&C=/^freq/"  lcol:blue ldash:solid lw:5
This would plot all ERP's with the condition label "rare" using red-dotted lines and all ERP's with a condition label starting with "freq" using 5mm-thick blue-solid lines.

Objects

Description

The [objects] section defines the drawing elements. If you want to see a diagram/map/line... in your drawing, you need to add a line to this list.

Since xavr allows interactive modifications of objects, it has to reflect such changes into the list. For this reason, whenever you have made such changes and enter the Edit - Configuration... dialog, xavr looks for the [objects] keyword in the file, throws away all stuff that follows and creates a completely new object list from the current internal state.

Therefore, the [objects] section has to be the last section in the file and should contain no special user formattings or comments!

Some object lines are generated as comments. Currently, this are the objects which form the legend. Since they are generated dynamically at each data loading time, it is not necessary to load them at layout creation time. If you are not satisfied with the automatic legend, you can comment out the [legend template], uncomment the legend objets and adapt them as needed. After this you have a static legend in the drawing.

Example

[objects]
text       x:148.00 y:185.00 txt:"Page Title" tsize: 8.00 tah:center
diagram    x: 38.00 y:126.00 tpl:default lab:FZ     
diagram    x: 38.00 y: 58.00 tpl:default lab:PZ     
maplegend  x:176.34 y: 26.46 tpl:default
map        x:172.00 y:108.00 tpl:default tmin: 0.200 tmax: 0.400 file:1
map        x:172.00 y: 38.00 tpl:default tmin: 0.200 tmax: 0.400 file:2

Reference

diagram
  x:
  y:      coordinates of the lower left corner of the diagram (in mm)
  tpl:    name of the assigned diagram template
  lab:    diagram label, the diagram will show the data for this channel
          if no sel:... is specified
  sel:    file/channel selection, overrides the template settings
map
  x:
  y:      coordinates of the lower left corner of the map field (in mm)
  tpl:    name of the assigned map template
  tmin:   start of the time slice for this map (in time_axis units)
  tmax:   stop of the time slice for this map (in time_axis units)
  file:   file selection
          (1 means: this map will show the first loaded/calculated file, 
           2 means: this map will show the second loaded/calculated file,
           ...
           0 means: this map will show the last loaded/calculated file)
  sel:    file selection, overrides file: and the template settings
maplegend
  x:
  y:      coordinates of the lower left corner of the
          map legend color bar(in mm)
  tpl:    name of the assigned map template
line
  x: 
  y:
  x2:
  y2:     coordinates of the line end points (in mm)
  l...:   linestyle parameters
  ang:    opening angle of the arrow head triangle (in degrees)
  len:    length of the arrow head triangle (in mm)
text
  x: 
  y:      coordinates of the text origin point (in mm)
  txt:    text string to be drawed
  t...:   textstyle parameters
epsf
  x: 
  y:      lower left corner of the illustration field (in mm)
  w:      width of the illustration field (in mm)
  h:      height of the illustration field (in mm); unspecified means
          fixed scale, height is computed from width and the EPS file 
          bounding box
  rot:    rotation angle for the included illustration (in deg); 
          unspecified means 0 or -90 (%%Orientation: Landscape)
  name:   name of a strictly conforming EPS file

EEP 3.1 - MPI/ANT(eeprobe@ant-software.nl), 13.07.1999
Copyright © 1996-99 Max-Planck-Institute of Cognitive Neuroscience. All rights reserved.
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