May 30, 2006 -- The healthy brain may hold memories we don't even remember are there, new research shows.
In The Journal of Neuroscience, experts report that the brain might house more memories than people realize, but that retrieving those memories can be tricky.
The researchers included Sander Daselaar, PhD, of the Netherlands' University of Amsterdam, and Roberto Cabeza, PhD, of Duke University. Participants were 14 healthy young adults at Duke University (average age: 21 years).
First, participants saw a list of 120 real words mixed with 80 nonsense words. Next, they saw another word list and tried to remember which words had been on the first list. Meanwhile, their brains were scanned with functional magnetic resonance imaging (fMRI).
While participants reviewed the second word list, their brain scans showed more activity in a certain brain area -- the posterior median temporal lobe -- when they saw words that had been on the first word list.
But participants didn't always remember that they'd seen those words before. Sometimes, they goofed and said they hadn't seen those words before.
In other words, the posterior median temporal lobe was more sensitive to memory than participants' consciousness, the researchers note.
'Album' of Memories
Another part of the median temporal lobe also attracted the scientists' attention. The anterior median temporal lobe showed more activity when participants thought they were seeing a new word, the study shows.
So, why did participants sometimes mess up their memory recall? It might be that two parts of their brain -- the posterior and anterior median temporal lobes -- might be dueling for the upper hand in deciding what actually happened in the past, the study notes.
In other words, memories might have a photo album in the brain, but sometimes we forget what's on all of the photo album's pages.