The goal of the present study was to investigate evoked power density and its topographical distributions of neural oscillatory dynamics underlying response execution and its inhibition using S-transform analysis as well as to assess its differences between controls and alcoholics. Based on the previously reported literature, it was hypothesized that (i) evoked power would increase with increasing cognitive control demand, such that response execution (Go) and suppression (NoGo) involving competing response tendencies (response conflict), and necessitating decision making will be characterized by a higher evoked power, (ii) evoked power density in NoGo trials would be distributed more anteriorly as compared with the Go trials in slow frequency bands, especially delta and theta, based on the evidence regarding the role of the prefrontal cortex in conflict monitoring, decision making, and response inhibition, and (iii) alcoholics would show lower evoked power compared to controls in different frequency bands. This effect would be substantial in the brain regions that respond to task situations with increased cognitive control demand, such as frontal regions. For this purpose, we derived evoked power of different frequency bands for both task conditions at all electrode locations.
