Six anatomical regions of interest (ROI) corresponding to the hippocampus, anterior cingulate, and dorsolateral prefrontal cortex were hand drawn bilaterally using AFNI’s graphical user interface by trained research assistants who used a human brain atlas for reference.30 These ROI’s were used as seed volumes to extract average time series data in subjects’ native space (see Figure 1). Due to low spatial resolution involved in fMRI, seeding the anterior cingulate unilaterally may include signal from both left and right hemispheres and ultimately make interpreting interhemispheric connectivity difficult. The ACC seed ROI was drawn by excluding slices on either side of the midline.
