Time-frequency-topographic analysis of induced power and synchrony of EEG signals during a Go/No-Go task.

Induced changes in electroencephalographic power and synchrony between pairs of electrodes were assessed during the Go/No-Go task in 15 young adults. Processes common to both conditions, such as attention, activation of working memory, letter identification, and discrimination processes were characterized by increased power and synchrony in the following frequency ranges: delta band (inhibition of the non-relevant stimuli), theta band (activation of working memory), and low alpha band in occipital regions immediately after the stimulus (withhold or control of the execution of a response), and decreased power in the high alpha band from 300 to 700 ms. However, the most important findings were those specific for each condition. Changes in power in frontal areas were observed immediately after the stimulus in delta and high alpha bands for the Go condition and in the theta band for the No-Go condition. Increased synchrony and power at 1 Hz from 350-500 ms and increased power at 1, 5 and 6 Hz after 300 ms in the No-Go condition may be related to inhibition. Other important difference between conditions was observed in the synchronization increases of the gamma band between 33 and 36 Hz in the Go condition, whereas synchrony decreased at these frequencies in the No-Go condition; these differences may be due to the preparation and execution of the motor response during the Go condition and its inhibition in the No-Go condition.