‘Time cells’ in brain enable ‘mental time travel’

PARIS: When we recall past events in our lives, we can often mentally replay an experience in the exact sequential order that it happened. Revisiting these episodic memories may feel like a seamless and ordinary activity, but the ability for our brains to encode events in temporal order—and then draw them up as sequential recollections later on—is an ongoing scientific mystery.

Now, a team led by Leila Reddy, a neuroscientist at the Brain and Cognition Research Center (CerCo) at the French National Centre for Scientific Research, has isolated some of the neural pathways in our brains that are responsible for recording and recalling the sequence of time.

Reddy and her colleagues carefully monitored brain activity in human patients as they completed tasks that required sequential memory. The results “suggest a robust representation of time in the human hippocampus,” a structure embedded deep in the brain, according to a study published on Monday in the Journal of Neuroscience.

The study reveals “a representation of an internal or inherent flow of time, that was not driven by something going on in the external world,” Reddy said in an email.

In addition to shedding light on the complex process of temporal organization within the brain, the new research could help patients with conditions that affect memory and the ability to process time.

“The hippocampus is important for judging the temporal order of events (among other things), and damage to the hippocampus can result in an impairment of memory for temporal order (for example remembering the order of a list of items),” Reddy said. “It's therefore important to understand how temporal information is represented in the brain, so as to be able to design interventions or treatments to reduce these deficits in memory.”

“Understanding the mechanisms for encoding time and memory will be an important area of research,” she concluded.