Precision functional mapping of human memory systems

Precision functional MRI has enabled identification of individual-specific network configurations. A comparison of these individual-specific maps with group-average maps has yielded novel insights into network organization of memory related brain systems. For example, the default mode network was previously thought to be comprised of three subsystems, but precision fMRI has demonstrated that one of those three subsystems may have arisen as an artifact of group averaging. Further, understanding of a second network-the parietal memory network-has been enhanced through precision fMRI. Specifically, one of the three canonical regions of this network-the posterior inferior parietal lobule-is identifiable within only about half of participants using current methods. In addition, 'network variants' have been identified, which are the existence of islands of network membership outside the typical configuration or regions that do not fall within the typical network assignment. The behavioral significance of such variants remains a topic for future consideration.