Estimating the Tangent Space of States of Consciousness via EEG Microstate Analysis: Age-Related Disappearance of Hyper-Flexible States

Ageing is associated not with a general decline in brain connectivity but with the disappearance of a subgroup of individuals who exhibit extremely high connectivity (>0.55) in electroencephalographic (EEG) microstate transitions. Analysis of data from the Dortmund Vital Study (608 participants aged 20–70, with a 5‑year follow‑up in 208 individuals) shows that most people maintain stable connectivity over five years, while the average decrease is driven by a sharp drop in a small subgroup (about 12 out of 208). The findings suggest that ageing involves the loss of hyper‑flexible neurodynamic states rather than a uniform contraction of the neurodynamic space.

Study at a glance

Abstract

This study proposes an operational estimate of the tangent space of states of consciousness based on the analysis of transitions between electroencephalographic (EEG) microstates. As a measurable parameter, we use connectivity — the average probability of microstate switching — which reflects the dynamical flexibility of the system. Using data from the open longitudinal Dortmund Vital Study (608 participants, age range 20–70 years, with a 5‑year follow‑up in 208 individuals), we demonstrate that ageing is associated not so much with a generalised decline in connectivity, but rather with the elimination of a subgroup exhibiting extremely high connectivity (>0.55): such individuals are present among younger adults but are virtually absent in the elderly. Longitudinal analysis confirms that the majority of subjects maintain stable connectivity over the 5‑year interval, while the observed decrease in mean connectivity is driven by a sharp drop in a small subgroup (approximately 12 out of 208). These findings suggest that ageing is linked not to a uniform contraction of the neurodynamic space, but to the disappearance of hyper‑flexible states. The proposed approach opens new avenues for the quantitative assessment of age‑related changes in neurodynamics.