The hippocampus is a seahorse-shaped structure deep in the brain that is critical for our ability to form new memories.

For example, both old and recent memories are replayed in the hippocampus during a particularly short, fast, and strong brainwave called a ripple.

These ripples may be very important for memory formation as electrical interruption of ripples in rats reduces the rat’s ability to form new memories.

Although it is known that memory changes as we age, and often not for the better, it was unknown whether ripples also change in the aged brain.

If ripples are affected by aging, then these changes might contribute to age-related memory loss.

Researchers in Stephen Cowen and Carol Barnes’ laboratories at the University of Arizona investigated this question by looking for age-related changes in the ripples of young and old rats. In a study published in the Journal of Neuroscience, they found that this brainwave occurred less often during sleep in old rats.

Daniel Gray, a graduate student in the Barnes lab and co-author of the study says, “It is possible that changes in the number of ripple events may contribute to the age-related memory decline seen in older individuals.

“Given the rapidly growing aged populations worldwide, it is becoming important to understand how memory-related brain states relate to changes in cognitive ability across lifespans.”