Detrimental impacts of mixed-ion radiation on nervous system function

Galactic cosmic radiation (GCR), composed of highly energetic and fully ionized atomic nuclei, can produce diverse deleterious effects on the body. In researching the neurological risks of GCR exposures, including during human spaceflight, various single-ion GCR irradiation paradigms have been shown to differentially disrupt cellular activity and overall behavior. However, it remains unclear how combined irradiation with a mix of multiple ions, more accurately recapitulating the space GCR environment, impacts the central nervous system. We therefore examined how mixed-ion GCR irradiation (containing combinations of protons, helium, oxygen, silicon and iron ions) influenced neuronal connectivity, functional generation of activity within neural circuits and cognitive behavior in mice. In electrophysiological recordings we find that space-relevant doses of mixed-ion GCR preferentially alter hippocampal inhibitory neurotransmission and produce related disruptions in the local field potentials of hippocampal oscillations. Such underlying perturbation in hippocampal network activity correspond to a range of deficits in cognitive tasks.