Third and in line with our previous observation (McCormick et al., 2013a), functional connectivity alterations of the DMN indicated episodic memory capacity reliably in patients with mTLE, but structural alterations did not. Whereas some studies indicate a relationship between structural integrity of the hippocampus and episodic memory (Poppenk and Moscovitch, 2011; Rausch, 1987), our results point to a more fundamental but indirect role of structural integrity. That is, the influence of structural DMN alteration on episodic memory capacity is mediated by alterations in functional networks. This finding is generally in line with the idea of the Human Brain Connectome project that the structural foundation of the brain enables its dynamic, functional repertoire which in turn is expressed as flexible behaviour (Sporns, 2013; Sporns et al., 2005; Honey et al., 2009; Honey et al., 2010).
