[OfflineAnalysis] Negative Topotimes

[TokyoBCI]

Hello,

I am currently rummaging through the Offlineanalysis.m to find a way to allow negative Topotimes for P300 offlineanalysis. As far as I understand, the lower bound on the topotimes isn't hardcoded somewhere, eventhough the static error message in line 224 hints towards such.

Do any of you know more about it ?

[mellinger]

Hi,

only time points after stimulus onset are used in the analysis, so it is not possible to enter negative topo times.

As a workaround, you can add the following to runBasicAnalysis.m, after line 281:

Code: Select all

timeshiftMs = 100;
timeshiftSamples=samplefreq * timeshiftMs / 1000;
signal=circshift(signal, timeshiftSamples);

Now, all time specifications will refer to 100ms prior to the specified time, i.e. when specifying "0ms", you will actually get a topography at -100ms samples.

HTH,
Juergen