Fourth, we show here for the first time that the whole pattern of functional DMN integrity captures between-subject variance in memory capacity better than focal activation or even one connection. This finding corroborates the idea that episodic memory capacity does not rely simply on the integrity of one region, even if that region, for example the hippocampus, is essential to episodic memory (McIntosh, 2000). Instead, our data indicate that episodic memory, even as measured in a clinical setting that is expressly designed to assess memory capacity involving MTL regions, is supported by a large-scale brain network. Of course the DMN is not defined by a pattern of activation directly related to memory performance, but it is largely co-extensive with networks involved in memory retrieval such as the autobiographical memory network and recollection memory (Spreng and Grady, 2010; Rugg and Vilberg, 2013; Buckner, 2012). Nonetheless, the extent to which our findings can be generalized to memory networks defined by such tasks and beyond patients with mTLE, in whom longstanding seizures and structural damage may result in unique patterns of plasticity or remodelling, remains to be seen.
