Intracortical functional connectivity during deep sleep reveals prosocial preferences

Prosociality is crucial for cohesive community functioning. Recently, we found that increased slow-wave activity during deep sleep in the right temporoparietal junction (TPJ), a key component of the social brain, is associated with stronger prosocial preferences. Building on this finding, we here investigate connectivity between the right TPJ and other regions of the social brain as a marker of inter-individual differences in prosocial preferences. Using whole-night high-density sleep electroencephalography (EEG) recordings from 54 participants (mean age = 21.5 ± 2 years; 28 females), we employed source localization to derive intracortical EEG functional connectivity during deep sleep in the slow-wave frequency range (0.8 to 4.6 Hz). We correlated connectivity between the right TPJ and 23 other key social brain regions with prosocial preferences, assessed in an incentivized public goods game with real monetary consequences. Our results revealed a negative correlation between prosocial preferences and connectivity for 22 of the 23 analyzed connections. Six of these connections demonstrated a significant negative correlation with prosocial preferences after adjusting for multiple testing (-0.36 ≤ rho ≤ -0.30; 0.006 ≤ p ≤ 0.038), indicating lower functional connectivity of the right TPJ with other social brain regions during deep sleep in individuals with stronger prosocial preferences. These results suggest that the benefits of deep sleep for prosocial decision-making may be enhanced when the right TPJ reduces its interactions within the social brain during this sleep stage.