and then compared across trials to determine whether amplitude or frequency modulation has occurred in bands of interest. The objective of the experiment was to produce the entrainment of alpha EEG activity by photic driving (through the use of a flashing background stimulus on which a non-flashing foreground stimulus appears), and to affect the entrainment by imposing an oddball task. Higher peak gamma amplitude was consistently observed during post-target-stimulus (300-750 ms) alpha suppression than at the time of maximum alpha activity during the immediate post-stimulus period. Further, the amplitude modulation of gamma (i.e., the amplitude envelope of the gamma activity) was at alpha frequency which was the frequency of entrainment). The authors suggested that there was an interaction between the alpha and gamma generating systems, in which gamma triggered alpha activity and was subsequently inhibited by it, thus producing the observed amplitude modulation. EROs have been used to understand not only normal cognitive processes but also neuro cognitive dysfunctions underlying psychopathological conditions and disorders that include alcoholism.
