The balance of local and distributed excitation shapes brain stability and reflects aging- and Alzheimer's disease-related alterations
- 1Korea University
Abstract
Human brain function emerges from the interplay between recurrent local activity and distributed inter-regional interactions. However, a biologically interpretable framework for quantifying this balance between the two factors at the whole-brain level remains lacking. Here, we extended an established biophysical model to quantify inter-regional excitation and newly introduced the recurrent ratio (R-ratio), a measure of the relative balance between intra- and inter-regional excitation. Dynamical analyses showed that an optimal R-ratio supports a trade-off between network stability and flexibility. Applying this framework to healthy aging and Alzheimer's disease revealed progressively increased R-ratios with advancing age and disease severity. In healthy individuals, higher R-ratios were associated with age-related alterations in brain morphology, molecular pathology, and cognitive function, whereas Alzheimer's disease was characterized by increased R-ratios accompanied by reduced dynamical persistence. Together, these findings establish the R-ratio as a biologically interpretable marker of whole-brain excitation balance and demonstrate its utility for linking biophysical mechanisms with large-scale brain dynamics, aging, and neurodegeneration.
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BibTeX
@misc{park2026balance,
title = {{The balance of local and distributed excitation shapes brain stability and reflects aging- and Alzheimer's disease-related alterations}},
author = {Y. Park and S. Kim and H. Park and T. D. Satterthwaite and B. Bernhardt and B.-y. Park},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.17.752536},
url = {https://www.biorxiv.org/content/10.64898/2026.09.17.752536v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - The balance of local and distributed excitation shapes brain stability and reflects aging- and Alzheimer's disease-related alterations
AU - Y. Park
AU - S. Kim
AU - H. Park
AU - T. D. Satterthwaite
AU - B. Bernhardt
AU - B.-y. Park
PY - 2026
DA - 2026/09/17
PB - bioRxiv
DO - 10.64898/2026.09.17.752536
UR - https://www.biorxiv.org/content/10.64898/2026.09.17.752536v1
AB - Human brain function emerges from the interplay between recurrent local activity and distributed inter-regional interactions. However, a biologically interpretable framework for quantifying this balance between the two factors at the whole-brain level remains lacking. Here, we extended an established biophysical model to quantify inter-regional excitation and newly introduced the recurrent ratio (R-ratio), a measure of the relative balance between intra- and inter-regional excitation. Dynamical analyses showed that an optimal R-ratio supports a trade-off between network stability and flexibility. Applying this framework to healthy aging and Alzheimer's disease revealed progressively increased R-ratios with advancing age and disease severity. In healthy individuals, higher R-ratios were associated with age-related alterations in brain morphology, molecular pathology, and cognitive function, whereas Alzheimer's disease was characterized by increased R-ratios accompanied by reduced dynamical persistence. Together, these findings establish the R-ratio as a biologically interpretable marker of whole-brain excitation balance and demonstrate its utility for linking biophysical mechanisms with large-scale brain dynamics, aging, and neurodegeneration.
ER -