Ageing involves significant neurophysiological changes that are both systematic while at the same time exhibiting divergent trajectories across individuals. These changes underlie cognitive impairments in elderly while also affecting the response of aged brains to interventions like transcranial direct current stimulation (tDCS). While the cognitive benefits of tDCS are more variable in elderly, older adults also respond differently to stimulation protocols compared to young adults. The age-related neurophysiological changes influencing the responsiveness to tDCS remain to be addressed in-depth. We review and discuss the premise that, in comparison to the better calibrated brain networks present in young adults, aged systems perform further away from a homoeostatic set-point. We argue that this age-related neurophysiological deviation from the homoeostatic optimum extends the leeway for tDCS to modulate the aged brain. This promotes the potency of immediate tDCS effects to induce directional plastic changes towards the homoeostatic equilibrium despite the impaired plasticity induction in elderly. We also consider how age-related neurophysiological changes pose specific challenges for tDCS that necessitate proper adaptations of stimulation protocols. Appreciating the distinctive properties of aged brains and the accompanying adjustment of stimulation parameters can increase the potency and reliability of tDCS as a treatment avenue in older adults.

中文翻译：

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用经颅直流电刺激刺激老年大脑：机遇与挑战

衰老涉及显着的神经生理学变化，这些变化既是系统性的，同时又在个体之间表现出不同的轨迹。这些变化是老年人认知障碍的基础，同时也会影响老年大脑对经颅直流电刺激 (tDCS) 等干预措施的反应。虽然 tDCS 的认知益处在老年人中变化更大，但与年轻人相比，老年人对刺激方案的反应也不同。影响对 tDCS 反应的与年龄相关的神经生理学变化仍有待深入解决。我们回顾和讨论的前提是，与年轻人中存在的更好校准的大脑网络相比，老年系统的表现更远离稳态设定点。我们认为，这种与年龄相关的神经生理学偏离稳态最佳值扩展了 tDCS 调节老化大脑的余地。尽管老年人的可塑性诱导受损，但这促进了即时 tDCS 效应的效力，以诱导定向塑性变化朝向稳态平衡。我们还考虑了与年龄相关的神经生理学变化如何对 tDCS 提出特定挑战，需要适当调整刺激方案。了解老年大脑的独特特性以及随之而来的刺激参数调整可以提高 tDCS 作为老年人治疗途径的效力和可靠性。尽管老年人的可塑性诱导受损，但这促进了即时 tDCS 效应的效力，以诱导定向塑性变化朝向稳态平衡。我们还考虑了与年龄相关的神经生理学变化如何对 tDCS 提出特定挑战，需要适当调整刺激方案。了解老年大脑的独特特性以及随之而来的刺激参数调整可以提高 tDCS 作为老年人治疗途径的效力和可靠性。尽管老年人的可塑性诱导受损，但这促进了即时 tDCS 效应的效力，以诱导定向塑性变化朝向稳态平衡。我们还考虑了与年龄相关的神经生理学变化如何对 tDCS 提出特定挑战，需要适当调整刺激方案。了解老年大脑的独特特性以及随之而来的刺激参数调整可以提高 tDCS 作为老年人治疗途径的效力和可靠性。