Scientists call the discovered cells “time cells”: they are responsible for the fact that when we feel good, time flies not noticeably, and when it is bad, it stretches.
They put a kind of time stamp on memories as they form. This allows us to recall sequences of events or experiences in the correct order.
In addition, they help memories form in a specific order, which makes them look like logical footage, rather than chaotic snippets.
“If the time cells“ create this indexing in time, you can piece all the memories together in a way that makes sense, ”explains Dr. Bradley Lega, senior study author and neurosurgeon at the University of Texas Southwestern Medical Center at Dallas.
But the new research is critical because “the human brain is always the ultimate arbiter,” says Dr. Gyorgy Bujak, professor of neurology at New York University.
Dr. Lega and his team found the “time cells” by examining the brains of 27 people who were awaiting surgery due to the consequences of severe epilepsy. As part of the preoperative preparation, these patients were placed electrodes in the hippocampus and another region of the brain responsible for navigation, memory and time perception.
In general, by itself, the hippocampus is part of the limbic system of the brain and the hippocampus of the formation. It is involved in the mechanisms of emotion formation, memory consolidation (that is, the transition of short-term memory to long-term memory), as well as spatial memory required for navigation. During the experiment, patients studied sequences of 12 or 15 words that appeared on a laptop screen for about 30 seconds.
Then, after a break, they were asked to remember the words they saw. Meanwhile, the researchers measured the activity of individual brain cells. And they found a small number of cells that “fire” at a specific time for each sequence of words.
The “time cells” that we found mark discrete chunks of time within this approximately 30-second window, ”explains the study’s author. These time stamps seemed to help people remember when they saw each word and in what order, he says. And the brain probably uses the same approach when we re-live experiences as powerful as falling off a bicycle.
The results of the experiment help explain why people with damage to the hippocampus can experience strange memory problems, concludes Dr. Bujak. But even though time cells are critical in making sequences, he stresses that they don’t really look like clocks, “ticking at a constant pace.”
Instead, the beats of the “time cells” continually speed up or slow down, depending on factors such as mood. “This happens, for example, when we ask when the COVID-19 pandemic will end. The days seem to be very long while we are alarmed. But when we are having a good time, it flies unnoticed, ”concludes Bujak.