[Eeglablist] ERSP calculation with no baseline

[Lustenberger Caroline]

Dear all
 
I have questions concerning the timef() function. 
I have EEGs from 2 nights (2 sleep EEGs) in one night with sham pulses
and another night with RF EMF pulses. First, my aim was to verify
whether the EMF pulse leads to an ERSP, but unfortunately, the baseline
is no real baseline (because the pulse affect the baseline from the
following pulse). Thus, I only have the EEG after the pulse. Then I
tried to compare the EEG after the EMF pulse with the EEG after sham
pulse (just trigger, no physiological effect). Therefore, I calculated
the ERSP using the timef() function, but set the baseline (NAN), because
I have no baseline (see function below). Now I have 2 ERSP (c1: EEG
after sham pulse, c2: EEG after EMF pulse).
 
EEG information: electrode C4, EEG  after pulse 3584 datapoints,
sampling rate (1024Hz), I need ERSP for Frequency range 1-4.5 Hz
% SHAM pulses

[ersp_c1(i).ersp, ersp_c1(i).itc ersp_c1(i).powbase, ersp_c1(i).times,
ersp_c1(i).freq, ersp_c1(i).erspboot]=timef(g_c1,3584,[0
3500],1024,0.25,'alpha',0.05,'maxfreq',4.5,'baseline',NaN);

% EMF pulse 

[ersp_c2(i).ersp, ersp_c2(i).itc ersp_c2(i).powbase, ersp_c2(i).times,
ersp_c2(i).freq, ersp_c2(i).erspboot]=timef(g_c2,3584,[0
3500],1024,0.25,'alpha',0.05,'maxfreq',4.5,'baseline',NaN);

--> Compare ersp_c1(i).ersp with ersp_c2(i).ersp for each timepoint
using t-tests (and all frequencies)

*	1. Question: Is the the timef() ,as I used it, correct? 
*	2. Question: Normally, the output ERSP values are log spectral
diffs. from baseline, but what do they describe, if no baseline is
available (baseline set NaN)? Do they then refelect Event related
spektral power after the pulse (in dB?)? 
*	3. Question: I set cycles number to 0.25 (that I earn frequency
range 1-4.5 with 0.25 Hz bins), can I use that? 
*	4. Question: Can I assume, when the ersp_c1(i).ersp differ from
the ersp_c2(i).ersp in any timepoint, that the EMF pulse leads to a
change in spektral power (after the pulse) for this timepoint(s)?

Thank you very much for your help.
 
Best wishes
Caroline 
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