Slow wave EEG oscillations during sustained attention to response task.

Objective: Although event related oscillations during attentional tasks have been studied comprehensively in the literature, EEG delta and theta during sustained attention task performance has not been extensively examined in the literature. The aim of our research group was to investigate the changes in slow wave oscillations (Delta and Theta) during attentional processes. Methods: Electroencephalography (EEG) of 13 healthy participants was recorded at the Fz, Cz, Pz, Oz locations during the auditory SART task which is a long and repetitive task requires withholding the response to the rare target stimuli. Time frequency decomposition was conducted via wavelet convolution using a Morlet-wavelet from 0.5 to 4 Hz (Delta) and 4 to 8 Hz (Theta). Average amplitude was calculated within 750 ms time window after the stimulus onset. Results: Delta F(3.36)=33.96, p<.001 and theta F(1.68, 20.10)= 29.32, p<.001 activity increased at mid-frontal region at the beginning of the experiment both in time domain (digital filtering) and time-frequency domain. However, decrease in fronto-central theta F(2.24)=3.55, p<.05, r=.36 activity was observed toward the end of the experiment. Conclusion: The changes in attention has been investigated based on new analytical methods event related oscillations (EROs) and inter-trial coherence (ITC) with respect to time domain and the localization of brain in the SART. Overall, sustained attention shown to increase fronto-central delta and theta activity during especially in behavioral inhibition process. This strong frontal midline delta and theta activity which is known to be parallel to executive control also occurs in inhibition control reported consistency with the literature. This increase was attenuated together with decreased delta and theta ITC towards the end of the experiment. Decrease in delta and theta activity can be associated with mental fatigue and decreased attention. [ABSTRACT FROM AUTHOR]