Chair of Automation and Control, Kiel University, Kaiserstraße 2, 24143, Kiel, Germany.
Kiel Nano, Surface and Interface Science KiNSIS, Kiel University, Christian-Albrechts-Platz 4, 24118, Kiel, Germany.
Sci Rep. 2023 Mar 27;13(1):5003. doi: 10.1038/s41598-023-31963-4.
Homeostasis comprises one of the main features of living organisms that enables their robust functioning by adapting to environmental changes. In particular, thermoregulation, as an instance of homeostatic behavior, allows mammals to maintain stable internal temperature with tightly controlled self-regulation independent of external temperatures. This is made by a proper reaction of the thermoeffectors (like skin blood vessels, brown adipose tissue (BAT), etc.) on a wide range of temperature perturbations that reflect themselves in the thermosensitive neurons' activity. This activity is being delivered to the respective actuation points and translated into thermoeffectors' actions, which bring the temperature of the organism to the desired level, called a set-point. However, it is still an open question whether these mechanisms can be implemented in an analog electronic device: both on a system theoretical and a hardware level. In this paper, we transfer this control loop into a real electric circuit by designing an analog electronic device for temperature regulation that works following bio-inspired principles. In particular, we construct a simplified single-effector regulation system and show how spiking trains of thermosensitive artificial neurons can be processed to realize an efficient feedback mechanism for the stabilization of the a priori unknown but system-inherent set-point. We also demonstrate that particular values of the set-point and its stability properties result from the interplay between the feedback control gain and activity patterns of thermosensitive artificial neurons, for which, on the one hand, the neuronal interconnections are generally not necessary. On the other hand, we show that such connections can be beneficial for the set-point regulation and hypothesize that the synaptic plasticity in real thermosensitive neuronal ensembles can play a role of an additional control layer empowering the robustness of thermoregulation. The electronic realization of temperature regulation proposed in this paper might be of interest for neuromorphic circuits which are bioinspired by taking the basal principle of homeostasis on board. In this way, a fundamental building block of life would be transferred to electronics and become a milestone for the future of neuromorphic engineering.
体内平衡是生物体的主要特征之一，它通过适应环境变化使生物体能够稳健地运作。特别是，体温调节作为一种体内平衡行为的实例，使哺乳动物能够通过独立于外部温度的精细自我调节来维持稳定的内部温度。这是通过热效应器（如皮肤血管、棕色脂肪组织（BAT）等）对广泛的温度扰动做出适当反应来实现的，这些反应反映在热敏神经元的活动中。这种活动被传递到相应的致动点，并转化为热效应器的动作，使生物体的温度达到所需的水平，称为设定点。然而，这些机制是否可以在模拟电子设备中实现仍然是一个悬而未决的问题：无论是在系统理论还是硬件层面上。在本文中，我们通过设计一个基于生物启发原理的温度调节模拟电子设备，将这个控制回路转化为一个实际的电路。具体来说，我们构建了一个简化的单效应器调节系统，并展示了如何处理热敏人工神经元的尖峰列车，以实现对未知但系统固有的设定点的稳定的有效反馈机制。我们还表明，设定点的特定值及其稳定性特性是由反馈控制增益和热敏人工神经元的活动模式之间的相互作用产生的，一方面，神经元的相互连接通常不是必需的。另一方面，我们表明，这种连接可能有利于设定点调节，并假设在真实热敏神经元集合中的突触可塑性可以作为额外的控制层发挥作用，增强体温调节的鲁棒性。本文提出的温度调节的电子实现可能对受体内平衡基本原理启发的神经形态电路感兴趣。通过这种方式，生命的基本构建块将被转移到电子学中，并成为神经形态工程未来的一个里程碑。
