A study on the neural mechanism of inhibition of return by the event-related potential in the Go/Nogo task

Inhibition of return (IOR) is a slowed response to a stimulus at recently cued locations when stimulus-onset asynchromes (SOAs) are longer than 250 ms. Using an uninformative peripheral cued Go/Nogo (commit/withdrawal response) task experiment, this study aimed to characterize the neural mechanism of IOR by studying not only the early event-related potentials (ERPs), P1 and N1, but also the late ERPs, Go/ Nogo-N2 and P3. Scalp topographies and LORETA showed that the changes in PI and N1, the cueing effects, were distributed mainly over the dorsal occipito-parietal areas, such as the bilateral middle occipital gyrus and the occipital portion of the cuneus. The changes in the late Nogo-N2 and P3 were distributed mainly over frontal-central areas, such as the right medial frontal gyrus. The Nogo-N2 was smaller and earlier in valid trials than in invalid trials, suggesting that the late component related to IOR was modulated by response preparation inhibition. The Nogo-P3 was larger and later in valid trials than in invalid trials, perhaps indicating that the control system (FEF) was free from an inhibitory marker in the cued locations. These data support a mechanism of IOR consisting of both sensory inhibition and response preparation inhibition. (C) 2008 Elsevier B.V. All rights reserved.