Neural networks involved in self-judgement in young and elderly adults

Recent studies have shown that both young and elderly subjects activate the ventromedial
prefrontal cortex (VMPFC) when they make self-referential judgements. However, the
VMPFC might interact with different brain regions during self-referencing in the two
groups. In this study, based on data from Ruby et al (2009), we have explored this issue
using psychophysiological interaction analyses. Young and elderly participants had to
judge adjectives describing personality traits in reference to the self versus a close friend
or relative (the other), taking either a first-person or a third-person perspective. The
physiological factor was the VMPFC activity observed in all participants during self
judgement, and the psychological factor was the self versus other referential process. The
main effect of first-person perspective in both groups revealed that the VMPFC was coactivated
with the left parahippocampal gyrus and the precuneus for self versus other
judgments. The main effect of age showed a stronger correlation between activity in the
VMPFC and the lingual gyrus in young compared to elderly subjects. Finally, in the
interaction, the VMPFC was specifically co-activated with the orbitofrontal gyrus and the
precentral gyrus when elderly subjects took a first-person perspective for self judgements.
No significant result was observed for the interaction in young subjects. These findings
show that, although the VMPFC is engaged by both young and older adults when making
self-referential judgements, this brain structure interacts differently with other brain
regions as a function of age and perspective. These differences might reflect a tendency
by older people to engage in more emotional/social processing than younger adults when
making self-referential judgements with a first-person perspective