Human brains are capable of ‘mental time travel,’ study says

The passage of time is all in your mind. 

Human brains independently measure episodic movement — that’s a trippy finding reported by French and Dutch researchers in a new study published Monday in the Journal of Neuroscience. 

Our brains possess “an internal or inherent flow of time, that was not driven by something going on in the external world,” neuroscientist and lead study author Leila Reddy told Vice of her team’s findings, which she referred to as evidence of the human mind’s “mental time travel” ability.

To get evidence of this hard-to-conceptualize concept, Reddy and her team studied the brains of epileptics who already needed invasive electrode implants in their brains independent of the research. 

“These patients have severe, drug-resistant epilepsy and are awaiting surgery,” Reddy told Vice of the study participants. “Part of the pre-surgical procedure involves implanting electrodes in the brain to monitor seizure activity. Once the electrodes are inserted in the brain, we ask the patients if they are willing to participate in short experiments for us, and we can record from single neurons to test different hypotheses.” 

Researchers found the participants’ brains’ “time cells” fired at specific moments, including moments when there weren’t external stimuli, suggesting they were responding to an internal sense of sequencing. 

“I think a big question here is to ultimately understand how memories are encoded,” Reddy told Vice. “Episodic memory, in particular, is the memory of what happened, when, and where. Time cells could provide the scaffolding for representing the ‘when.’ Emerging evidence suggests that the same hippocampal neurons might also encode the ‘where’ and the ‘what,’ providing a broader framework for encoding memories.”

Moving forward, to better understand how humans process time, she believes researchers will need to look even closer at the mechanisms by which the brain encodes both time’s passage and memories.