Scientists Watch Rats String Memories Together

A summary of experiments recently published in the journal Science sheds light on what memories are, how they form and gives clues about how the system can fail by using electrode implants to track nerve cells firing in the brains of rats. “My own introspective experience of memory tends to be one of discrete snapshots strung together, as opposed to a continuous video recording,” said an assistant professor of neuroscience at the Johns Hopkins University School of Medicine. “Our data from rats suggest that our memories are actually organized that way, with one network of neurons responsible for the snapshots and another responsible for the string that connects them.” During the study, the research team focused their experiments on a group of nerve cells in the hippocampus known as place cells. In previous experiments, researchers learned that when a rat wants to get from point A to point D, it maps out its route mentally before starting on its journey and they could see this happen by implanting many tiny wires in the brains of the rats in order to monitor the activity of more than 200 place cells at a time. By doing so, they found that the place cells representing point A would fire first, followed by those for point B, then C and D. Their most recent study shows a higher resolution “map” of the same process, which revealed gaps in between points A, B, C and D — not because they weren’t capturing enough place cell activity, but because there are actual “gaps” between discrete “memories” in the rats’ brains. To read more about this study, click here.