At this stage, the researchers placed the rats back into the maze that they had previously memorized, finding that their ability to remember their way around was completely unaffected by their level of exercise or the number of new hippocampal neurons developed in the intervening period.
Therefore, the authors conclude that exercise “does not impair memory recall ability in a rat model despite substantially increasing neurogenesis,” which is good news, as it means humans may not have to pay for physical fitness with their memories after all.
Though more work is needed in order to determine why hippocampal neurogenesis causes memory loss in some animals but not others, the team suggest that it may have something to do with certain differences in the structure of neurons between species. For instance, rat neurons do not connect in the same way as mouse neurons, and may therefore be able to form without destabilizing existing connections and erasing memories.
Given that human neurons have more in common with those of rats than those of mice, the researchers are hopeful that hitting the gym won’t squeeze our old knowledge out of our brains.
Unlike mice, humans who exercise probably don't lose any memories. Pavel Ilyukhin/Shutterstock