Nano-scale simulation of neuronal damage by galactic cosmic rays

Area of Science:

• Neuroscience
• Astrobiology
• Computational Biology

Background:

• Deep space radiation poses a significant threat to neuronal function, yet its effects at the nano-scale remain poorly understood.
• In silico modeling offers a powerful approach to quantitatively analyze radiation-induced neuronal damage, complementing experimental studies.

Purpose of the Study:

• To conduct the first nano-scale computational analysis of galactic cosmic ray (GCR) irradiation in a realistic neuron geometry.
• To assess the nano-scale dosimetry, physics processes, and fluence patterns resulting from GCRSim and SimGCRSim spectra.

Main Methods:

• Thousands of in silico CA1 pyramidal neuron models with stochastic dendritic spines were constructed.
• Simulations utilized the TOol for PArticle Simulation (TOPAS) and TOPAS-nBio Monte Carlo toolkits to model the GCRSim and SimGCRSim spectra.
• Nano-scale dosimetry, physics processes, and fluence patterns were analyzed.

Main Results:

• For a 0.5 Gy GCRSim dose, an average of 250 ± 10 ionizations per micrometer of dendritic length and specific ionizations in dendritic spines were reported.
• Neuronal energy deposition by protons and alpha particles decreased hyperbolically with increasing primary particle energy.
• No significant differences in average physical responses were found between GCRSim and SimGCRSim spectra.

Conclusions:

• This study provides the first nano-scale simulation of realistic neuron geometries under GCR and SimGCRSim spectra.
• The findings offer crucial quantitative data for theoretical models and experimental interpretations in space radiation biology.
• Results can guide future research designs for understanding and mitigating radiation effects on the nervous system.