EGI Neuroscan BTI CTF BDF
| EGI |
| Neuroscan |
| BTI |
| CTF |
| BDF |
EGI:
conditions are named according to the HIST-files. If trigger bits have
standard names (DIN1, DIN2, etc.) the DIN-number specifies the bit
order (1 is the lowest bit (1), 2 the next higher (2), 3 the next
higher (4) etc. ). If bits have non-standard names specified by the
user, bit orders are assigned according to their order of occurence in
the HIST-file: the first bit-code encountered is take as lowest bit,
the second as the next higher etc. [Top]
Neuroscan:
(under
construction)[Top]
BTI:
(under
construction)[Top]
CTF:
(under
construction)[Top]
BDF: For BDF data, trigger data is stored as an
extra channel in the data file. This status channel data is analyzed
and written to a user editable text file by the function emegsreadbdfmarker, that identifies
non-zero values of the status channel and saves one line for each value
change, along with its begin time, end time and duration. This
resulting textfile has the same name as the data file, except that the
file extension is set to HIST. As only value changes are extracted, it is
important to set the status channel back to zero by the presentation
software, before presenting a trial of the same status value. An
example of a HIST-file is given below: a Timing variable is defined
(T), with it's first column beeing the status channel value, the second
the begin time in seconds since file begin, the third the end time and
the fourth the duration.
T = [...
5
17 17.582 0.582
;...
1
17.582 17.9141
0.3321 ;...
5
17.9141 18.24743
0.33333 ;...
5
18.24743 18.58076
0.33333 ;...
5
18.58076 18.91409
0.33333 ;...
5
18.91409 19.24742
0.33333 ;...
1
19.248 19.582
0.334 ;...
3
19.582 19.9141
0.3321 ;...
1
19.9141 20.2471
0.333 ;...
1
20.2471 20.58043
0.33333 ;...
3
20.5801 20.9141
0.334 ;...
1
20.9141 21.2461
0.332 ;...
.
.
.
You can manually change this file
to obtain different trial sorting, condition naming or data segments.
Note that only the condition name (first column) and the begin time
(second column) are used for extracting data epochs: relative to the
begin time, pretrig samples and posttrig samples are extracted and
stored as evoked data epochs. The end time and duration are ignored for
standard ERP analyses. [Top]