An ancient memory-enhancing technique known to enable short-term recall of large quantities of information also produces durable memories that can still be accessed up to four months later, according to a new study with 17 of the world's top "memory athletes" and 50 non-expert participants in the March 5 issue of Science Advances.
This method of loci technique, which involves mentally placing items to be remembered along an imagined path, actually decreased activation in brain areas typically involved in spatial memory processing, which are important for long-term memory, while increasing neural connections that store new information as long-lasting memories.
"This was somewhat surprising to us, as better performance is typically associated with increased engagement of different brain regions," said Isabella Wagner, a postdoctoral researcher at the Social, Cognitive & Affective Neuroscience Unit in the University of Vienna and the lead author of the study. "What we saw here is the opposite: training decreased activity in these regions so that lower brain activation leads to better memory. Intuitively, this could be interpreted as 'neural efficiency' — less resources might be needed to achieve better performance."
The findings suggest that the method of loci might be useful for enhancing durable memories even in people without extraordinary memory prowess.
"Long-term memory formation is important during daily life — it defines who we are," said Wagner. "Future studies should investigate whether potential memory trainings might help slow down the detrimental effects of age."
The method of loci, which was originally developed in ancient Greece, entails mentally placing material one wishes to remember at landmarks on an imagined path, which can be retrieved at will by retracing the imaginary route. These "memory journeys" serve as tools for mentally consolidating and organizing information — kind of like acronyms (think ROY G. BIV for remembering the colors of the rainbow), but with objects. This technique is applied today in events such as the World Memory Championships, in which individuals flex their memory muscles by accurately memorizing and reciting huge quantities of arbitrary information.
Boris Konrad, a researcher at the Donders Institute for Brain, Cognition and Behaviour in The Netherlands and an author of the study, is a memory champion himself. Konrad holds four Guinness World Records and has broken several memory competition world records, including memorizing 201 names or 280 words within the span of 15 minutes.
But while Konrad and other "memory athletes" have dazzled the world with their seemingly superhuman powers of recall, researchers were unsure whether the method of loci enables long-lasting memories or merely short-term recollections that quickly fade with time.
Training the Brain
To better understand the long-term applications of this technique, Wagner and colleagues first assessed 17 experts ranked among the world's top memory athletes, all of whom were experts in the method of loci. The researchers compared the athletes' performance in word list encoding and order recognition tasks with that of 16 people matched for age, sex, handedness, and intelligence.
Next, Wagner and colleagues recruited a new cohort of 50 non-expert participants who either underwent an intense six-week method of loci training regime, a less rigorous working memory training, or no intervention at all.
Participants in the method of loci training were first given detailed instructions in the laboratory, including a predetermined set of routes they were told to envision to help them learn the technique. The participants then trained at home for about 30 minutes each day using an online platform, which taught them how to memorize word lists while practicing different imaginary routes. The final level of the training included a list of 40 random words that participants had to recall perfectly.
"We showed them a route through our institute which was something like 'entrance door, reception desk, plant next to desk, stand with leaflets, head of famous scientist sculpture, etc.,'" said Konrad. "For additional locations, they were instructed to make a route through their home and provided an example such as 'bed, desk, computer, bookshelf, books, window.'"
The researchers assessed these participants' memory performance and brain function using magnetic resonance imaging (MRI) both before and after the training and administered a behavioral retest after four months to evaluate their longer-term post-training memory performance. While the method of loci training group freely recalled an average of about 50 words during the retest, the working memory group only remembered about 30 words, and the untrained control group remembered about 27 words.
Through MRI, Wagner and colleagues found decreased activation in several areas of the brain known to play a role in spatial memory processing in both memory athletes and the non-expert participants that received method of loci training. Decreased activity in these and other regions, along with enhanced connections between the brain's hippocampus and cortex areas, was associated with better memory performance four months later in the non-experts.
"What was beautiful to see was that the effects were so strikingly similar between memory champions and the memory training group after training and directly related to performance increases," said Wagner. "The method of loci technique obviously requires time and regular practice and might thus not be suited for everyone, but it is definitely possible to 'boost' memory and reach high or even exceptional memory performance."