Rowland Conor, Smith Julian H, Moslehi Saba, Harland Bruce, Dalrymple-Alford John, Taylor Richard P
Physics Department, University of Oregon, Eugene, OR, United States.
School of Pharmacy, University of Auckland, Auckland, New Zealand.
Front Netw Physiol. 2023 Jan 25;3:1072815. doi: 10.3389/fnetp.2023.1072815. eCollection 2023.
Fractal geometry is a well-known model for capturing the multi-scaled complexity of many natural objects. By analyzing three-dimensional images of pyramidal neurons in the rat hippocampus CA1 region, we examine how the individual dendrites within the neuron arbor relate to the fractal properties of the arbor as a whole. We find that the dendrites reveal unexpectedly mild fractal characteristics quantified by a low fractal dimension. This is confirmed by comparing two fractal methods-a traditional "coastline" method and a novel method that examines the dendrites' tortuosity across multiple scales. This comparison also allows the dendrites' fractal geometry to be related to more traditional measures of their complexity. In contrast, the arbor's fractal characteristics are quantified by a much higher fractal dimension. Employing distorted neuron models that modify the dendritic patterns, deviations from natural dendrite behavior are found to induce large systematic changes in the arbor's structure and its connectivity within a neural network. We discuss how this sensitivity to dendrite fractality impacts neuron functionality in terms of balancing neuron connectivity with its operating costs. We also consider implications for applications focusing on deviations from natural behavior, including pathological conditions and investigations of neuron interactions with artificial surfaces in human implants.
分形几何是一种用于捕捉许多自然物体多尺度复杂性的著名模型。通过分析大鼠海马体CA1区锥体神经元的三维图像，我们研究了神经元树突内的各个树突如何与整个树突的分形特性相关。我们发现，树突呈现出由低分形维数量化的出人意料的温和分形特征。通过比较两种分形方法——传统的“海岸线”方法和一种研究树突在多个尺度上的曲折度的新方法，这一点得到了证实。这种比较还使树突的分形几何与更传统的复杂性度量相关联。相比之下，树突的分形特征由高得多的分形维数量化。使用改变树突模式的变形神经元模型，发现偏离自然树突行为会在神经网络中引起树突结构及其连接性的巨大系统性变化。我们讨论了这种对树突分形性的敏感性如何在平衡神经元连接性与其运营成本方面影响神经元功能。我们还考虑了针对偏离自然行为的应用的影响，包括病理状况以及对人类植入物中神经元与人工表面相互作用的研究。
