The present study aimed to test several hypotheses regarding the patterns of functional connectivity underlying retrieval of spatiotemporal contextual details. By leveraging a new approach, whole brain functional connectivity with graph theory, we were able to better understand the contributions of different brain regions to episodic memory retrieval. Under the different conditions we examined (such as correct versus incorrect or spatial versus temporal trials), particular networks emerged as important to episodic memory retrieval. Specifically, successful retrieval resulted in greater overall connectivity combined with greater connectivity to specific hubs, including the hippocampus. Past fMRI studies employing univariate analyses have also focused on a primary role for the hippocampus in episodic memory56212223242526, although studies have also shown activation in the parahippocampal cortex627, prefrontal cortex82829303132, precuneus3133, visual cortex31, posterior parietal cortex/angular gyrus3435, and retrosplenial cortex3637. These findings have not been unified across studies, however, and univariate methods alone cannot indicate whether and to what extent these disparate areas interact38. Thus, our results provide a potentially new perspective on the neural basis of episodic memory, emphasizing the importance of interactions across multiple brain regions rather than the computations of a single primary brain region (such as the hippocampus).
