Effects of partial- or whole-body exposures to ⁵⁶Fe particles on brain function and cognitive performance in rats

On exploratory class missions, such as a mission to Mars, astronauts will be exposed to particles of high energy and charge (HZE particles). Exposure to HZE particles produces changes in neuronal function and can disrupt cognitive performance. Cells throughout the entire body, not just the brain, will be impacted by these particles. To determine the possible effects that irradiation of the body might have on neuronal function and cognitive performance, rats were given head-only, body-only or whole-body exposures to ⁵⁶Fe particles. Cognitive performance (novel object recognition, operant responding) was tested in one set of animals; changes in brain function (oxidative stress, neuroinflammation) was tested in a second set of rats. The results indicated that there were no consistent differences in either behavioral or neurochemical endpoints as a function of the location of the irradiation. These results suggest that radiation to the body can impact the brain, therefore it may be necessary to re-evaluate the estimates of the risk of HZE particle-induced changes in neuronal function and cognitive performance.