Two fMRI studies, both from the same group of investigators, have examined the relationship between prenatal marijuana exposure and adolescent/young adult neural functioning during tasks requiring response inhibition and visuo-spatial working memory, while controlling for covariates such as IQ, prenatal nicotine, alcohol and caffeine exposure, and current marijuana, nicotine and alcohol use121, 125. In the first study, subjects with and without prenatal marijuana exposure underwent fMRI while performing a two condition Go/No-Go task. There were no significant group differences for reaction time and errors of omission for either condition, however the prenatally exposed group had significantly more errors of commission on the more difficult of the two tasks. The amount of prenatal marijuana exposure was significantly positively related to bilateral prefrontal cortex (PFC) and right premotor cortex activity, and significantly negatively related to left cerebellar activity, suggesting to the authors the possible need for increased effort to perform the task, perhaps as a compensatory response to altered or delayed development of the PFC or a larger neural system involving these three brain regions. In the second study, fMRI was conducted
