For the time domain analysis the event-related potentials (ERPs) for the first 1000 ms after stimulus presentation were calculated for each group and participant, for subsquent analysis of the most relevant ERP components: segments were averaged according to the groups they belonged to and a the area of the LPP component, between 400 and 600 ms was exported and analyzed for differences between the groups for all subjects, using paired t-tests for the electrodes in the
medial centroparietal area (CZ, CPZ and PZ). Finally, analysis in the spatial dimension was done using LORETA. First, time-average LORETA images for long periods of time were calculated in order to compare with fMRI data that does not have the same temporal resolution of the EEG. These images were obtained using statistical non-parametric mapping methodology (Nichols 4 and Holmes, 2002). Then the ERPs were compared using a topographic analysis of variance (TANOVA, Strik et al., 1998) for the first 1000 ms. This method tests, with high time resolution, for differences between scalp potentials, using statistical comparisons carried out using the nonparametric randomization methodology, which
corrects for multiple testing (time and electrodes). Only the periods of time that were significantly different between the groups of brands were used in the following step. In this last step, for all time segments longer than 10 ms, statistical analyses of functional LORETA images were performed. This step is justified because different scalp potentials can only be due to different neuronal source distributions
For the time domain analysis the event-related potentials (ERPs) for the first 1000 ms after stimulus presentation were calculated for each group and participant, for subsquent analysis of the most relevant ERP components: segments were averaged according to the groups they belonged to and a the area of the LPP component, between 400 and 600 ms was exported and analyzed for differences between the groups for all subjects, using paired t-tests for the electrodes in the
medial centroparietal area (CZ, CPZ and PZ). Finally, analysis in the spatial dimension was done using LORETA. First, time-average LORETA images for long periods of time were calculated in order to compare with fMRI data that does not have the same temporal resolution of the EEG. These images were obtained using statistical non-parametric mapping methodology (Nichols 4 and Holmes, 2002). Then the ERPs were compared using a topographic analysis of variance (TANOVA, Strik et al., 1998) for the first 1000 ms. This method tests, with high time resolution, for differences between scalp potentials, using statistical comparisons carried out using the nonparametric randomization methodology, which
corrects for multiple testing (time and electrodes). Only the periods of time that were significantly different between the groups of brands were used in the following step. In this last step, for all time segments longer than 10 ms, statistical analyses of functional LORETA images were performed. This step is justified because different scalp potentials can only be due to different neuronal source distributions
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