The Comparison between Visually and Auditory Oddball Tasks in the EEG Experiment with Healthy Subjects

Abstract

Purpose: We compare the two oddball tasks for auditory and visually in the healthy subjects with the EEG experiment. In this regard, we compare three different dimensions of the EEG, including regional, longitudinal, and functional effects. The regional dimension defines as the region of the brain, the longitudinal dimension is the repetition of the stimuli, and the functional dimension is the whole curve of ERP, evoked related potential, instead of the only amplitude and latency of it. We also study the trial effects for each stimulus in each task.

Materials and Methods: Seventeen healthy patients, 11 of whom are males, have participated in this study. The dataset was downloaded from the internet. The EEG dataset was cleaned. There are three trials and each has a total of 25 target stimuli per group. The functional data analysis, Hybrid principal component analysis, were used to estimate three effects among two different visually and auditory oddball tasks. The 95% Bayesian credible sets were estimated with three trials of each stimulus and each group. The Generalized Additive Mixed Model was used for studying the effect of trials as random effects.

Results: The first eigenfunctions of functional and longitudinal dimensions and first and second eigenvector of regional dimensions were estimated. The 95% Bayesian credible sets indicated that the variability between trials exists and is different for each stimulus and each target. The GAMM model indicates that the interaction effects in the functional dimension are statistically significant for both tasks. The interaction effect in the longitudinal dimension is not statistically significant in the Auditory Task and is statistically significant in the visual task. The brain regions are statistically significant and the main effect of the target stimuli is significant for auditory (P-Value: <0.00) and is not significant for the visual tasks (P-Value: >0.06). The interaction effect for target stimuli and the region of the brain is only significant for Occipital, Parietal, and Right Temporal (P-values < 0.05) for the auditory task. The random effects of trials are statistically significant in most of them.

Conclusion: The functional data analysis provides many statistical methods to analyze the EEG dataset. The HPCA can capture the functional-longitudinal and regional dimensions and we also study the new dimension, trials with GAMM. The different regions of the brain have not the same activity in these two tasks. The repeating of the stimuli has a positive effect on complex tasks. The between trial's variability are statistically significant, and we conclude to study this effect to show the stability of the trials.