Complexity Of EEG Reflects Socioeconomic Context And Geofootprint

The fine scale structure and resulting activity of the brain are largely shaped by experience, suggesting that the faster rate and complexity of experience offered by modern civilization may have significant impact on human brain dynamics. Here we defined a new measure of complexity of the EEG signal and compared it across populations spanning incomes from <$1/day to ~$410/day with a wide range of access to features of modern life such as urban environments, higher education, electricity, motorized transport and telecommunication. Complexity across our sample spanned a 2.75-fold range, separating into two distinct distributions of pre-modern and modern experience. Furthermore, complexity scaled systematically with various technologies and experience factors, of which travel or geofootprint had the strongest relationship. Complexity also had a steep non-linear relationship with income that leveled out at an income of ~$30/ day. Finally, it was strongly correlated to performance on a pattern completion task indicating its relevance as a cognitive measure. In light of growing income inequality and divergence in access to the tools of modern living across the globe, our findings have significant implications for social policy.