Age-group differences in medial cortex activity associated with thinking about self-relevant agendas.

Self-relevant thought (e.g., rating how characteristic trait adjectives are of self versus others) activates areas of medial cortex including both anterior (medial frontal gyrus and/or anterior cingulate cortex) and posterior (posterior cingulate cortex and/or precuneus) regions (for reviews, see, e.g., Cavanna & Trimble, 2006; Macrae, Moran, Heatherton, Banfield, & Kelley, 2004; Northoff et al., 2006; Ochsner et al., 2005; Vogt & Laureys, 2005). Identifying the functional specificity of subregions of medial cortex in self-relevant thought is the focus of current empirical and theoretical work in social-cognitive neuroscience (e.g., Johnson et al., 2006; Schmitz & Johnson, 2007; Uddin, Iacoboni, Lange, & Keenan, 2007; for reviews and conceptual discussions, see, e.g., Lieberman, 2007; Mitchell, 2008; Northoff et al., 2006; Northoff & Bermpohl, 2004; Olsson & Ochsner, 2008). One approach is to investigate the role(s) of medial cortex when individuals process different motivationally significant personal agendas, such as hopes and aspirations versus duties and obligations (related to a promotion or prevention self-regulatory focus, respectively, Higgins, 1997) (Johnson et al., 2006; Johnson, Nolen-Hoeksema, Mitchell, & Levin, 2008). Such agendas guide our perception, thought, and behavior, and help to define our “self”. Using functional magnetic resonance imaging (fMRI), Johnson et al. (2006) compared young adults’ brain activity associated with thinking about each of these agendas versus thinking about non self-relevant control topics (e.g., shape of USA). Both thinking about hopes and aspirations and thinking about duties and obligations were associated with greater activity than the control condition in an anterior medial region (medial frontal gyrus/anterior cingulate cortex) and a posterior medial region (cingulate cortex/precuneus). This was consistent with previous findings of activity in these areas during self-focused thought (for reviews, see, e.g., Cavanna & Trimble, 2006; Macrae et al., 2004; Northoff et al., 2006; Ochsner et al., 2005; Vogt & Laureys, 2005). In addition, there was a double dissociation. In anterior medial cortex, a more dorsal area (anterior cingulate/dorsomedial frontal gyrus) showed greater activity in both self-relevant conditions (which did not differ) than the control condition, and a more ventral portion of anterior cingulate showed relatively greater activity related to thinking about hopes and aspirations than to thinking about duties and obligations. In posterior medial cortex, a more superior/posterior area (posterior cingulate, cuneus, precuneus) showed greater activity in both self-relevant conditions (which did not differ) than the control condition, and a more inferior/anterior area (lingual gyrus, posterior cingulate, parahippocampus) showed relatively greater activity related to thinking about duties and obligations than hopes and aspirations. This dissociation suggests differential involvement of anterior and posterior medial cortex in self-relevant motivational thinking depending on either the content of such thought or the specific component processes called upon to generate, retrieve, or evaluate such information. Johnson et al. (2006) suggested several hypotheses, including that medial frontal cortex is associated with a more inward-directed self-focus, whereas posterior medial cortex is associated with a more outward-directed, social, or contextual focus when thinking about personal agendas (see, Northoff et al., 2006 for a similar distinction). One way to further investigate the relationship of these areas to the processing of motivationally-relevant information is to examine the pattern of brain activity associated with thinking about such agendas in populations that show reliable behavioral differences in motivational focus. Normal aging is associated with significant changes in motivational orientation. For example, there is evidence suggesting that older adults are more “other” or “outward” focused, whereas young adults are more “self” or “inward” focused in their motivational orientations. Older adults express, for instance, strong concerns for the state of the world and the future of family members and subsequent generations (McAdams & de St. Aubin, 1998) and family members make up a substantial part of their social networks (Antonucci, 2001). In addition, compared to young adults, older adults consider a more restricted range of motivational goals as self-relevant, for example, they focus on fewer, more central, goals and life domains than do young adults (Riediger & Freund, 2006; Staudinger, Freund, Linden, & Maas, 1999). Also, whereas young adults’ goals tend to center on growth and acquisition (e.g., of knowledge or physical health), older adults increasingly focus on maintenance and retention of resources and loss prevention (Ebner, Freund, & Baltes, 2006; Heckhausen, 1997; Ogilvie, Rose, & Heppen, 2001). These behavioral findings suggest that we should find age-group differences in activity in anterior and posterior medial cortex when young and older adults think about personal agendas: relatively greater activity in medial prefrontal cortex in young than older adults, related to an inward self-focus and concern for acquisition, and possibly greater activity in posterior medial cortex in older than younger adults, related to an outward-focus and concern for loss prevention. A recent fMRI study (Gutchess, Kensinger, & Schacter, 2007) did not find age-related differences in medial cortex activity when young and older participants were asked to rate the self-relevance of trait adjectives. Nevertheless, given the behavioral evidence for age-group differences in motivational focus, we would expect age-group differences in medial cortex related to differences in the processing engaged by young and older adults when they are asked to think about more motivationally relevant themes. This would support the idea that these areas are not simply “self regions”, but rather are differentially sensitive to certain types of self-focus or the particular content of self-relevant thought. Thus, the goal of the present study was to assess potential age-group differences in medial prefrontal cortex and medial posterior cortex in self-relevant thinking by examining the pattern of activity of young and older adults as they considered the motivationally significant agendas of hopes and aspirations and duties and obligations.