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Title: Cognitive effects of proton irradiation at differing energy levels

item HEROUX, NICHOLAS - University Of Maryland
item CARRIHILL-KNOLL, KIRSTY - University Of Maryland
item RABIN, BERNARD - University Of Maryland
item Shukitt-Hale, Barbara

Submitted to: Society for Neuroscience Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/25/2013
Publication Date: 11/9/2013
Citation: Heroux, N., Carrihill-Knoll, K., Rabin, B.M., Shukitt Hale, B. 2013. Cognitive effects of proton irradiation at differing energy levels. Society for Neuroscience Abstracts and Proceedings. 2013. Program # 766.15.

Interpretive Summary:

Technical Abstract: During exploratory class missions to space outside of the magnetic field of the Earth, astronauts will be exposed to various forms of radiation including solar particle events (SPE) which are predominantly composed of protons. As such it is important to characterize the cognitive effects of exposure to proton radiation. Previous research has indicated that exposure to high energy protons (1000 MeV/n) may disrupt neurocognitive performance. The research also suggests that the relative biological effectiveness (RBE) of the different components of space radiation may vary as a function of particle energy. Since the majority of proton radiation emitted from SPEs is low energy it is necessary to determine whether there are similar differences in effectiveness as a function of proton energy. A series of behavioral studies were conducted to characterize the role of particle energy in the disruptions of neurocognitive performance seen in proton irradiation. In the initial experiments Male Sprague-Dawley rats were exposed to 1000 MeV/n protons at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL). After irradiation the rats were shipped to UMBC and tested on a series of behavioral tests: novel object recognition, spatial recognition and memory, elevated plus maze, and operant responding on an ascending fixed-ratio schedule. Cognitive performance was variably disrupted in the experiments using rats exposed to 1000 MeV/n protons at the NSRL. The final study in the series compared the effects of different particle energies (1000 MeV/n and 150 MeV/n) on cognitive performance in the behavioral tasks. Although the results of this experiment were not consistent with previous results, there were no differences in performance as function of proton energy. As such, the possible risk of a performance deficit resulting from exposure to protons cannot be reliably determined.