Almost everyone has experienced one memory triggering another, like coming across a photo from when we were in high school might bring back memories of where the school was located, activities we may have participated in and the like. But explanations for that phenomenon have been hard to prove until now. University of Pennsylvania researchers seem to have come up with the first scientific evidence that memories formed in the same context become linked, the foundation of the theory of episodic memory.
“When I remember my grandmother, for example, I pull back all sorts of associations of a different time and place in my life said professor Michael Kahana of the Department of Psychology in the School of Arts and Sciences to esciencenews. “I’m also remembering living in Detroit and her Hungarian cooking. It’s like mental time travel. I jump back in time to the past, but I’m still grounded in the present.”
The Penn team combined an old psychological research technique, having subjects memorize and recall a list of unrelated words, with precise brain activity data that can only be acquired via neurosurgery.
“We can do direct brain recordings in monkeys or rats, but with humans one can only obtain these recordings when neurosurgical patients, who require implanted electrodes for seizure mapping, volunteer to participate in memory experiments,” Kahana said. “With these recordings, we can relate what happens in the memory experiment on a millisecond-by-millisecond basis to what’s changing in the brain.”
University of Pennsylvania researchers think the findings provide a brain-based explanation of a memory phenomenon that people experience every day. In a way, they seem to have proved that time travel, at least mental time travel, is a reality we all share.
“This is why two friends you met at different points in your life can become linked in your memory,” Kahana said. “Along your autobiographical timeline, contextual associations will exist at every time scale, from experiences that take place over the course of years to experiences that take place over the course of minutes, like studying words on a list.”
Flickr photo by bark