In this study we combined event-related fMRI with a parametric manipulation of the go nogo paradigm to examine the effect of preceding context on inhibitory processes. Nogo trials were preceded by either 1, 3, or 5 go trials and then compared to one another. Two distinct patterns of activation were associated with behavioral inhibition: First, the ventral prefrontal cortex, cingulate gyrus, and superior parietal regions showed a context effect with an increase in MR signal to nogo trials with increasing number of preceding go trials. Second, anterior regions in the supplementary and premotor cortex showed an increase in MR signal on the nogo condition after 5 preceding go trials, but not after only 1 or 3. A model using the BOLD response in our data was used to verify that the effect of context was not an artifact of the randomization scheme used in the design.
Bibliographical noteFunding Information:
We thank D. Silbersweig and E. Stern for their consultation on designing the paradigm and B. van Berckel for his help in subject recruitment. This work was supported in part by an NIMH K01 award to B.J.C. and by awards from the Netherlands Royal Academy of the Arts and Sciences (KNAW), foundation “De Drie Lichten” and the Dutch Society for Neuropsychology to S.D.
- Functional MRI