Objective: 

Examination of EEG power bands during resting, cold stress (CS), mental stress (MS)and MA+CS conditions.

Methods: 

Eleven channel EEG was recorded from 7 volunteered university students during resting, cold stress (CS) mental stress MS) and MS+CS conditions. Blood pressures and heart rates of the participants were also recorded during aforementioned conditions. An arithmetical calculation task (Mental calculation) was used as Mental Stress. Cold stres was induced by immersing hands alternately into cold water (4°C). Paired t-tests and power spectra were analysed with repeated measures ANOVA with condition (4), channel (11) within subject factors. Reduced degrees of freedom (Greengouse-Geisser) were used to counter violations of sphericity assumption where necessary.

Results: 

There were significant differences in each power band for the Condition factor. delta: F(1,7)= 79,93, p<000.1; theta: F(1,7)=77,52, p<0.001; alfa: F(1,7)=17,75; p<0.001; beta: F(1,7)=118,37, p<0.001.

In pairwise comparisons LSD was used. Delta and theta powers were most apparently increased in the MS+CS (p<0.001). Alpha power was significantly decreased in the MS condition. Beta power was significantly increased in the MS and MS+CS. Channel and Channel X Condition interaction was not significant.

Conclusions: 

Our preliminary results suggest that during MS, there is a cortical activation and increased vigilance reflected by alpha decrease and beta increase. Whereas in double stress (MS+CS), presence of concomittant increases of delta, theta and beta bands, might suggest decrease of vigilance in the background of increased arousal.