Connectivity maintenance cost in the brain CMC II: energetic margins, local reserves, and failure thresholds

Abstract

This theoretical study develops the Connectivity Maintenance Cost (CMC) framework by modelling how biological and neural networks lose functional integration when the resources available for connectivity maintenance fall below critical thresholds. Rather than treating energetic expenditure as a simple consequence of momentary activity, the model distinguishes the recurrent cost of preserving long-range communication, hub participation, synaptic reliability, recurrent processing, and network-wide coordination. CMC II proposes that highly connected and integration-dependent operations may possess smaller maintenance margins and therefore become unstable before more local, modular, or redundant functions under progressive energetic, synaptic, or pathological constraint. This principle provides a mechanistic framework for investigating the sequence of network failure in neurodegeneration and other conditions affecting biological integration. The manuscript formalises the relationship between maintenance demand, available capacity, and functional stability; distinguishes hypothesis from established evidence; and identifies measurable predictions using connectomic, metabolic, electrophysiological, and longitudinal data. It extends the original Connectivity Maintenance Cost framework presented in CMC I: https://doi.org/10.5281/zenodo.22018535.