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 on the same subjects during a visuo-spatial 2-back test. There were no significant performance differences between the prenatally exposed and unexposed groups. However, as in the previous study, the amount of prenatal marijuana exposure was significantly positively related to increased activity in the left medial PFC, the left inferior frontal gyrus, and the left cerebellum, and significantly negatively related to activity in the right dorsolateral, medial, and ventral PFC, left pre-supplemental motor cortex, and the right parahippocampal gyrus. The authors speculated that prenatal marijuana exposure may have altered the lateralization and functional connectivity of multiple brain regions, which, along with the PFC, are important in the performance of a complex EF task.
