Ionizing radiation reduces the numbers of neurons expressing activity-regulated cytoskeleton-associated protein (Arc) in the hippocampal dentate gyrus (DG). It is currently unclear if that change relates to cognitive function. We assessed the effects of 1 Gy of head-only 56Fe-particle irradiation on hippocampus-dependent and hippocampus-independent fear conditioning and determined how those changes related to Arc expression within the DG. Irradiated mice that did not receive tone-shock pairings on day 1 showed less freezing in the same context on a second day and a lower fraction of Arc-expressing neurons in the free (lower) blade of the DG than sham-irradiated mice. Those data suggested reduced hippocampus-dependent spatial habituation learning. Changes in Arc expression in the free blade correlated positively with freezing in mice that did not receive tone-shock pairings. However, irradiated mice that did receive tone-shock pairings showed enhanced contextual freezing but a reduced percentage of Arc-expressing neurons in the enclosed (upper) blade. Changes in Arc expression correlated negatively with freezing in mice that received tone-shock pairings. In animals receiving cued fear conditioning, radiation did not affect cognitive performance or the fractions of Arc-expressing neurons. While the relationship between Arc expression and cognitive performance is complex, our data suggest that radiation effects on hippocampus-dependent cognition might depend on the prominence (salience) of environmental stimuli and blade-specific Arc expression.
Effects of 56Fe-Particle Cranial Radiation on Hippocampus-Dependent Cognition Depend on the Salience of the Environmental Stimuli
- Views Icon Views
- Share Icon Share
- Search Site
Jacob Raber, Susanna Rosi, Ayanabha Chakraborti, Kelly Fishman, Catherine Dayger, Matthew J. Davis, Laura Villasana, John R. Fike; Effects of 56Fe-Particle Cranial Radiation on Hippocampus-Dependent Cognition Depend on the Salience of the Environmental Stimuli. Radiat Res 1 October 2011; 176 (4): 521–526. doi: https://doi.org/10.1667/RR2635.1
Download citation file: