From a press release
earlier today from Toronto's Baycrest Centre for Geriatric Care:
What happens in the brain when we remember our own past?
[ ... Read the full press release ... ]
Toronto, CANADA --Researchers are using functional magnetic resonance imaging (fMRI) to probe brain activity in search of the answer. According to a new fMRI study using a "diary" method to collect memories, it all depends on what we're thinking about!
Researchers have known for decades that thinking about autobiographical facts is different from thinking about autobiographical episodes that happened only once. Since both kinds of thoughts can occur at the same time when people talk about their past, researchers have struggled to find an effective way to separate them.
The new study, published in the current issue of the Journal of Cognitive Neuroscience (16:9), is the first brain imaging study of its kind to use diary-like memories collected by volunteers. It was led by The Rotman Research Institute at Baycrest Centre for Geriatric Care.
Over a period of several months prior to the brain scan, volunteers documented dozens of unique events from their personal lives on a micro cassette recorder (episodic memories). At the same time, they recorded statements about personal facts of their lives (semantic memories). The researchers played these recordings back to the volunteers while their brains were being scanned with fMRI.
The results showed that the two types of autobiographical memory engaged different parts of the brain, even when the memories concerned the same contents. For example, the semantic thought "Every Friday afternoon I take the dog for a long walk" produced brain activity in one set of regions, whereas the episodic thought "One Friday afternoon my dog got away and I spent 45 minutes running after him" produced brain activity in a different set of regions.
"Although both kinds of memory are autobiographical, they serve very different purposes," says lead investigator Dr. Brian Levine, a senior scientist with The Rotman Research Institute at Baycrest and associate professor in Psychology and Neurology, University of Toronto. "Factual autobiographical memory grounds us in time and gives continuity to our lives. Episodic autobiographical memory allows us to travel in time, to relive our past."