“…The DMN is typically found deactivated during cognitive tasks requiring externally focused attention and activated during internally focused mental tasks, such as episodic memory retrieval, mental state attribution, and visual imagery (Buckner, Andrews-Hanna, & Schacter, 2008;Mason et al, 2007;Raichle et al, 2001;Shulman et al, 1997). In addition to the regional atrophy and neuronal hypometabolism affecting DMN nodes, disruptions in functional connectivity of the DMN in AD dementia have been widely replicated (Agosta et al, 2012;Binnewijzend et al, 2012;Greicius, Srivastava, Reiss, & Menon, 2004), and have been linked to core memory and visuospatial deficits Supekar, Menon, Rubin, Musen, & Greicius, 2008;Zhang et al, 2010). Intriguingly, connectivity disruption and impaired task-related down regulation of the DMN may already emerge during the presymptomatic phase of AD as modeled cross-sectionally on the basis of imaging evidence of cortical amyloid pathology Sperling et al, 2009) or an apolipoprotein E4 (APOE4) positive genotype, which is a major genetic risk factor for late onset AD (Damoiseaux et al, 2012;Machulda et al, 2011;Persson et al, 2008).…”