occipital cortex) for both age groups, and did not differ across groups (Fig. 4b). Directionality analysis provided complementary support for these findings. Results from the theta band suggested prefrontal cortex was the sender and temporal cortex was the receiver for younger adults (t41 = −2.959, p = 0.005, dz = 0.457). However, PSIs in older adults did not reach significance (t41 = −0.382, p = 0.705, dz = 0.059). In contrast, no preferred direction in the flow of information between temporal and occipital regions was apparent in the gamma band for either age group (ts41 < 1.489, ps > 0.144, dsz < 0.230). The results suggest a preferential impact of age on maintenance-related neural connectivity, whereby local communication among sensory areas indexed by short-range occipitotemporal gamma synchronization appears intact in older age, but global communication directed by prefrontal cortex indexed by long-range frontotemporal theta synchronization appears disconnected or insufficiently active in older compared to younger people.
