The brain's default network and eudaimonic - hedonic interaction. (a - c) The brain's default network has been linked to self-awareness, remembering the past and prospecting the future (Addis et al. 2007; Gusnard et al. 2001; Schacter et al. 2007). Some components overlap with pleasure networks, including midline structures such as the orbitofrontal, medial prefrontal and cingulate cortices. We wonder whether happiness might include a role for the default network, or for related neural circuits that contribute to computing relations between self and others, in evaluating eudaimonic meaning and interacting with hedonic circuits of positive affect. Examples show key regions of the default network such as (d) the anterior cingulate and orbitofrontal cortices that have a high density of opiate receptors (Willoch et al. 2004), (e) have been linked to depression (Drevets et al. 1997), and (f) its surgical treatment. (g) have been implicated by connectivity analyses (Beckmann et al. 2009), (h) are implicated in pleasure-related cognitive functions such as monitoring, learning and memory (Kringelbach 2005), (i) or in self-knowledge, person perception and other cognitive functions (Amodio and Frith 2006). (j) The default network may change over early life in infants and children (Fair et al. 2008; Fransson et al. 2007), (k) in pathological states including depression and vegetative states (Laureys et al. 2004), (l) and after cortical lesions that disrupt reality monitoring and create spontaneous confabulations (Schnider 2003).