Mind reading may have taken a step away from the realm of science fiction, thanks to a new study in which researchers taught a computer to spot specific memories as a person was having them.
To be sure, science is a long way off from hooking people up to a device and knowing their thoughts. But the study showed that past events leave unique "memory traces" in a portion of the brain called the hippocampus, traces that can be distinguished from one another in brain scans.
The study is published in Current Biology.
Memories in the hippocampus
"We found that our memories are definitely represented in the hippocampus," senior study author Eleanor Maguire, a professor at the Wellcome Trust Centre for Neuroimaging at University College London, said in statement. "Now that we've seen where they are, we have an opportunity to understand how memories are stored, and how they may change through time."
In the experiment, researchers had 10 people view three short films multiple times and asked them to memorise what they saw.
The seven-second films showed different actresses in common, relatively similar, scenarios: In one, a woman rifled through her purse to find an envelope and then dropped it in a mailbox; in another, a woman finished a cup of coffee and dropped the cup in a trash can.
That type of recollection is considered an episodic memory, or an a memory of a collection of events, as opposed to a semantic memory, such as being able to recall a fact, or an implicit memory, such as being able to tie your shoes, explained Martin Monti, a neuroscientist at the Medical Research Council's Cognition and Brain Sciences Unit in Cambridge, England.
Afterward, participants were asked to recall either a specific film, or any one of the films, while having their brains scanned using functional MRI. While scans cannot actually look at the firing of groups of neurons (called voxels), it does report changes in blood flow that signal activity in particular brain areas, Monti explained.
A computer algorithm then analysed the patterns generated when the participants "remembered" and attempted to identify which film the volunteer was recalling.
The computer could accurately predict with about 45% accuracy which film a person was thinking about during the scan. Since there were three films, chance would have provided about 33% accuracy.
Memories recorded in regular pattern
"The algorithm was able to predict correctly which of the three films the volunteer was recalling significantly above what would be expected by chance," lead study author Martin Chadwick, a cognitive neuroscientist at University College London, said in a statement. "This suggests that [people's] memories are recorded in a regular pattern."
Previous research has shown the hippocampus, located deep within the brain's medial temporal lobe, is associated with creating and consolidating memories. That's basically the brain's process of putting together sights, sounds and smells, all of which may be processed in different areas of the brain, and bringing them together in a memory, Monti said.
So, will scientists one day be able to use brains scans to read your mind?
That's probably a long way off, because fMRIs are a technically advanced - but still rather crude - means of viewing neuronal activity. And though researchers were able to tell the difference between memories in the strict confines of the lab, that's a far cry from being able to "read" the memories that make up the whole of the human experience, Monti said.
"Our tools are not that fine-grained. It's like trying to read a book when you don't know the language and your eyeglasses are crummy," he said.
Treatment for memory problems
One of the beauties of such an experiment, however, is the possibility that a better understanding of the brain could open the door to new treatments for memory problems, said Paul Sanberg, a professor of neurosurgery and director of the University of South Florida Centre for Ageing and Brain Repair.
"The study confirms these memories are found within the hippocampus," Sanberg said. "The more we understand about memories and how they are formed and stored, the closer we will get to understanding problems people have with memories, whether from injuries, aging or degenerative disease." - (HealthDay News, March 2010)