Meeting Abstract
Methylmercury is a widespread neurotoxic stressor in both aquatic and terrestrial environments, yet many terrestrial species have been overlooked in studying its effects. Using the zebra finch (Taeniopygia guttata) as a model songbird, we previously showed that birds exposed to sublethal levels of dietary methylmercury throughout their lifespans displayed impaired spatial learning; however, in this study mercury did not affect our measure of spatial memory nor were differences in hippocampus volume observed. The hippocampus is a region of the brain related to spatial cognition, so this difference in learning could be due to effects of mercury on neural processes in the hippocampus rather than simply volume. We hypothesized that methylmercury would hinder neural processes such as migration of young neurons to the hippocampus, survival of immature neurons to this region, and integration of immature neurons into existing neural networks within the hippocampus. To test this hypothesis, we extracted brains from zebra finches that had been exposed to methylmercury throughout their lives and whose spatial cognition had been tested. We predict that mercury-exposed birds will display decreased density of immature and mature neurons in the hippocampi, quantifying these measures utilizing immunohistochemical staining.
