Neurogenesis in the Adult Brain

National Institute Of Mental Health

Investigators

Linked publications, trials & patents

Abstract

This project focuses on the interactions between experience and adult neurogenesis in the hippocampal region of the brain. We are interested in understanding how experiences, including positive and stressful experiences, regulate adult neurogenesis and how the new neurons alter behavior in different situations. We study the regulation and function of adult neurogenesis in rats and mice, which show continued production of new neurons throughout adulthood similar to that in primates, including humans. The hippocampus is thought to play an important role in spatial learning and memory, but many spatial tests for rodents are also stressful, making it difficult to determine whether any changes in behavior are due to effects on spatial abilities or stress response. We developed a labyrinth maze and tested rats abilities to navigate through the maze to earn a food reward. Several different configurations of the maze were tested in order to ask whether new neurons were important for decreasing interference between memories for different paths. We compared normal rats with transgenic rats that we developed to allow us to specifically inhibit neurogenesis in adulthood. We found that rats lacking adult neurogenesis learned the mazes as well as the control rats and remembered the correct paths for several weeks. In one maze configuration, rats without new neurons performed much better than the controls, which we determined through further testing was due to the presence of an aversive odor (peppermint) in the maze that distracted the rats from the task only if they had ongoing adult neurogenesis. This finding suggests that new neurons are not necessary for non-stressful spatial learning but that they play an important role in determining whether animals focus on a task or attend to background stimuli. We also investigated the effects of sedatives on the birth and survival of new neurons in the adult hippocampus. We found that sedation itself had no effect on adult neurogenesis, but specific sedatives altered cell proliferation or cell survival, suggesting that decreased neurogenesis in the young adult DG could potentially mediate some of the effects of sedation on cognitive function.