Laboratory of Radiation Biology, Joint Institute for Nuclear Research, Dubna 141980, Russia.
Division of Natural Sciences, National University of Mongolia, Ulaanbaatar 210646, Mongolia.
Phys Med. 2019 Jan;57:88-94. doi: 10.1016/j.ejmp.2019.01.002. Epub 2019 Jan 3.
The study of evaluating radiation risk on the central nervous system induced by space-born charged particles is very complex and challenging task in space radiobiology and radiation protection. To overcome computational difficulties in this field, we developed simplified neuron models with properties equivalent to realistic neuron morphology. Three-dimensional structure and parameters of simplified and complex neuron models with realistic morphology were obtained from the experimental data. The models implement uniform random distribution of spines along the dendritic branches in typical hippocampal neurons. Both types of models were implemented and tested using Geant4 Monte Carlo radiation transport code. Track structure simulations were performed for ion beams with typical fluxes of galactic cosmic rays expected for long-term interplanetary missions. The distribution of energy deposition events and percentage of irradiated volumes were obtained to be similar in both simplified and realistic models of pyramidal and granule cells of the rat hippocampus following irradiation. Significant increase of computational efficiency for detailed microdosimetry simulations of hippocampus using simplified neuron models was achieved. Using designed neuron models we have constructed 3D model of the rat hippocampus, including pyramidal cells, mature and immature granular cells, mossy cells, and neural stem cells. Computed energy deposition in irradiated hippocampal neurons following a track of iron ion suggests that most of energy is accumulated by dense population of granular cells in the dentate gyrus. Proposed approach could serve as a complementary computation technique for studying radiation-induced effects in large scale brain networks.
研究由空间带电粒子引起的中枢神经系统辐射风险是空间辐射生物学和辐射防护中非常复杂和具有挑战性的任务。为了克服该领域的计算困难，我们开发了具有等效于真实神经元形态的简化神经元模型。简化和具有真实形态的复杂神经元模型的三维结构和参数是从实验数据中获得的。模型在典型海马神经元的树突分支上实现了棘突的均匀随机分布。这两种类型的模型都使用 Geant4 蒙特卡罗辐射输运代码进行了实现和测试。针对长期行星际任务中预期的典型银河宇宙射线通量的离子束进行了轨迹结构模拟。在照射后，在大鼠海马的锥体和颗粒细胞的简化和真实模型中，获得了沉积能量事件的分布和照射体积百分比相似。使用简化神经元模型对海马体进行详细微观剂量学模拟的计算效率显著提高。使用设计的神经元模型，我们构建了包括锥体细胞、成熟和未成熟颗粒细胞、苔藓细胞和神经干细胞在内的大鼠海马体的 3D 模型。计算铁离子轨迹照射后的海马神经元中的能量沉积表明，大部分能量被齿状回中密集的颗粒细胞群积累。所提出的方法可以作为研究大尺度脑网络中辐射诱导效应的补充计算技术。
