{
  "id": 9031677,
  "title": "Transient excitability and synaptic consolidation support stable memory despite neural drift",
  "url": "https://urgent.news/2026/09/21/transient-excitability-and-synaptic-consolidation-support-stable",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-21T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.15.751773v1?rss=1"
  },
  "original_language": "en",
  "account": "Long-term memories persist even as the neural cells that store them undergo changes, a phenomenon known as representational drift. This drift varies across different brain regions: the hippocampus can reorganize its connections within hours, while cortical networks remain relatively stable over days to weeks. This discrepancy creates a challenge for systems consolidation, a process by which the hippocampus guides the formation of long-lasting cortical memory traces.\n\nTo better understand this process, researchers constructed a two-region neural network model focusing on the hippocampus (HPC) and anterior cingulate cortex (ACC). The model included factors such as region-specific synaptic plasticity, excitability-dependent changes in neuronal activity, and the coupling between the hippocampus and cortex. When these regions operated independently, the faster turnover of synapses in the hippocampus led to significant drift, whereas the ACC's stable connectivity helped maintain a more consistent cortical ensemble.\n\nIn a fully functional circuit, however, the hippocampus sends signals to the ACC, which in turn influences the ACC's neurons. This communication also introduces variability from the hippocampus into the cortex, undermining the emerging memory trace and making it harder to recall the memory. To counteract this instability, the researchers discovered that increasing the intrinsic excitability of ACC neurons during the initial consolidation period could stabilize the cortical ensemble without inhibiting hippocampal drift.\n\nWhen the model simulated the removal of learning-induced changes in the ACC, the memory relied more on the hippocampus's plasticity initially. This suggests that the memory formation process involves a sequence of events: first, the hippocampus recruits and temporarily modifies its connections, then transient changes in the cortical intrinsic plasticity stabilize the memory trace, and finally, persistent changes in synaptic connections cement the memory. By understanding these sequential mechanisms, researchers hope to shed light on how the brain transitions from a dynamic hippocampal representation to a stable cortical memory.",
  "summary": "Long-term memories remain behaviorally stable despite turnover in the neuronal populations that encode them. This representational drift differs across brain regions: hippocampal representations can reconfigure within hours, whereas cortical ensembles remain comparatively stable over days to weeks. This asymmetry poses a challenge for systems consolidation, in which hippocampal activity is…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "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."
}