Neurophysiological changes with age probed by inverse modeling of EEG spectra

ObjectiveTo investigate age-associated changes in physiologically-based EEG spectral parameters in the healthy population.MethodsEyes-closed EEG spectra of 1498 healthy subjects aged 6–86 years were fitted to a mean-field model of thalamocortical dynamics in a cross-sectional study. Parameters were synaptodendritic rates, cortical wave decay rates, connection strengths (gains), axonal delays for thalamocortical loops, and power normalizations. Age trends were approximated using smooth asymptotically linear functions with a single turning point. We also considered sex differences and relationships between model parameters and traditional quantitative EEG measures.ResultsThe cross-sectional data suggest that changes tend to be most rapid in childhood, generally leveling off at age 15–20 years. Most gains decrease in magnitude with age, as does power normalization. Axonal and dendritic delays decrease in childhood and then increase. Axonal delays and gains show small but significant sex differences.ConclusionsMean-field brain modeling allows interpretation of age-associated EEG trends in terms of physiological processes, including the growth and regression of white matter, influencing axonal delays, and the establishment and pruning of synaptic connections, influencing gains.SignificanceThis study demonstrates the feasibility of inverse modeling of EEG spectra as a noninvasive method for investigating large-scale corticothalamic dynamics, and provides a basis for future comparisons.