Changes in the temporal variability of the EEG functional connectivity during aging

This work is aimed at investigating changes in the temporal variability of EEG functional connectivity (FC) during agin. The variability in the FC has been linked to cognitive performance. The study was carried out in two groups of healthy subjects: one of 10 adults between 50-65 years old and another of 15 subjects ranging 66-85 years. EEG recordings were made at rest using 16 monopolar channels: under eyes closed (EC) and under hyperventilation (HV). The cortical FC between all EEG channel pairs was estimated from an index (L) of nonlinear generalized synchronization. For each subject and condition, the global connectivity (GC) of each area/channel with the rest of them was calculated, then the GC average and the GC temporal variability (TVC) of such connectivities was computed from the GC mean and standard deviation of successive EEG recordings respectively. The changes with age and condition of GC and TVC of each cortical area were estimated via a MANOVA. We found that the GC does not change with age during OC or HV, but the TVC of all cortical areas is significantly higher (p<0.01) for subjects under 65 and mainly for the central, temporal and parietal areas (p<0.01). It is concluded that TVC decreasing with aging may be related to cognitive performance deficits.