Using PPI analysis, we found group differences in connectivity between the STN and median cingulate cortex, a default network region (Fransson and Marrelec, 2008), when contrasting a low-level (0-back) and a cognitively demanding (2-back) task. In the High resiliency group, these regions showed greater coupling in 0-back than in 2-back condition, whereas the Low resiliency group showed the opposite pattern. A recent PET study showed that stimulation of the STN decreased metabolism in a large region of the cingulate gyrus, centered in BA24 and encompassing the median cingulate region identified in the present study, substantiating a link between these regions (Le Jeune et al., 2010). Anatomically, in non-human primates, the cingulate regions of BA23 (controlling movement execution) and BA24 (controlling higher cognitive aspects of movement) both send projections to the STN providing integrated motor information to the basal ganglia (Takada et al., 2001). Consistent with this, we found that connectivity between the STN and median cingulate was related to increased processing speed during the low demand 0-back condition. As an influence on inter-regional communication efficiency, this connectivity may represent a pathway linking resiliency and flexible implementation.
