Rapid loss of fine motor skills after low dose space radiation exposure

Sensorimotor function, motivation, and attentional processes are fundamental aspects of behavioral organization during skilled tasks. NASA's planned expedition to Mars will expose astronauts to space radiation (SR) that has the potential to impair performance in mission critical tasks. Impairments in task accuracy and movement kinematics have been previously reported during string-pulling behavior ~7 months after SR exposure. If similar SR-induced sensorimotor deficits emerge at earlier times, then astronauts may have compromised in-flight performance disruptions while performing skilled tasks in critical situations, such as when manipulating controls or performing seat egress. Due to the possibility that such performance losses may compromise mission success, it is critical to determine if sensorimotor, motivation, or attentional deficits occur acutely after SR exposure at a time point that corresponds to in-flight performance. Male Wistar rats were thus exposed to either 10 cGy simplified galactic cosmic radiation (GCRsim), 10 cGy ⁴Helium (⁴He), or no radiation at all (Sham), and string-pulling behavior was assessed approximately 72 h later. Following exposure to SR, rats (⁴He) took more time to approach the string to initiate string-pulling behavior and to pull in the string to reach the Cheerio (⁴He and GCRsim) relative to Sham rats. ⁴He-exposed rats also exhibited a greater number of misses and less contacts relative to both Sham and GCRsim-exposed rats. Further, rats exposed to ⁴He demonstrated less concentrated reach endpoints with both the left and right hands compared to GCR-exposed rats. This work suggests that sensorimotor function and motivation and/or attentional processes were impaired 72 h after ⁴He-radiation exposure.