Multimodal cortical connectome in the default mode network across the adult lifespan

The default mode network (DMN) critically underpins cognitive and affective functions throughout the adult lifespan; however, detailed insights into its complex neuroarchitecture and connectivity patterns across aging remain limited. Leveraging the open-access CamCAN dataset, comprising structural and diffusion magnetic resonance imaging (MRI) alongside magnetoencephalography (MEG) data from 599 adults spanning ages 18 to 88 years, we systematically investigated age-associated changes in multimodal connectomes within the DMN. Our analyses revealed a progressive decline in both structural and functional connectivity among DMN subregions with advancing age. Additionally, MEG-based connectivity assessment demonstrated age-related decreases in high-frequency oscillatory activity (alpha, beta, gamma bands) accompanied by increases in low-frequency oscillations (theta band). Integrating structural data with neurophysiological measures further revealed age-dependent shifts in neurophysiological-structural coupling within the prefrontal cortex, characterized by strengthened coupling at theta frequencies but weakened coupling at higher frequencies. Conversely, coupling within the posterior cingulate cortex consistently declined across all examined frequency bands. Notably, theta-band coupling within the prefrontal cortex significantly correlated with age-related memory performance variations. Collectively, our findings delineate nuanced changes in DMN information transmission dynamics across adulthood, underscoring its promise as a neurobiological biomarker reflective of cognitive aging heterogeneity.