{
  "id": 9625968,
  "title": "The balance of local and distributed excitation shapes brain stability and reflects aging- and Alzheimer's disease-related alterations",
  "url": "https://urgent.news/2026/09/24/the-balance-of-local-and-distributed-excitation-shapes-brain",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-24T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.17.752536v1?rss=1"
  },
  "original_language": "en",
  "account": "The human brain's function arises from the complex interplay between local activity and inter-regional interactions. Yet, a clear framework to measure this balance between these two factors across the entire brain has been missing. In this study, researchers built upon an existing biophysical model to quantify inter-regional excitation and introduced a new metric called the recurrent ratio (R-ratio). This ratio reflects the relative balance between excitation that occurs within specific brain regions (intra-regional) and between different regions (inter-regional).\n\nThrough dynamical analyses, the researchers found that an optimal R-ratio helps maintain a balance between network stability and flexibility. When they applied this framework to study healthy aging and Alzheimer's disease, they observed a trend of progressively higher R-ratios in both conditions as age increased or disease severity progressed. In healthy individuals, a higher R-ratio correlated with changes in brain morphology, molecular pathology, and cognitive abilities that are commonly associated with aging. In contrast, Alzheimer's disease was marked by elevated R-ratios combined with reduced dynamical persistence, indicating a loss of stability in brain network dynamics.\n\nOverall, these findings present the R-ratio as a biologically meaningful indicator of the balance between excitation within and between brain regions. This new metric not only enhances our understanding of the underlying mechanisms at play but also offers a valuable tool for linking large-scale brain dynamics with the processes of aging and neurodegeneration.",
  "summary": "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…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 3,
    "also_reported_by": [
      {
        "outlet": "PsyPost",
        "title": "Alzheimer’s proteins predict early brain shrinkage before dementia symptoms appear",
        "url": "https://urgent.news/2026/09/23/alzheimers-proteins-predict-early-brain-shrinkage-before-dementia",
        "published": "2026-09-23T22:00:30.000Z"
      },
      {
        "outlet": "Medical Xpress",
        "title": "How the APOE4 gene damages brain blood vessels in Alzheimer's disease",
        "url": "https://urgent.news/2026/09/24/how-the-apoe4-gene-damages-brain-blood-vessels-in-alzheimers-disease",
        "published": "2026-09-24T15:00:05.000Z"
      }
    ]
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}