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“Mind-reading” experiment highlights how brain records memories

March 13, 2009
Courtesy Wellcome Trust Centre
and World Science staff

New re­search adds to mount­ing ev­i­dence that it’s pos­si­ble to “read” mem­o­ries just by look­ing at brain ac­ti­vity. Ex­pe­ri­menters found that our no­tion of where we are is rec­orded in reg­u­lar pat­terns, con­tra­ry to cur­rent sci­en­tif­ic think­ing.

Demis Has­s­abis and El­ea­nor Maguire at the Well­come Trust Cen­tre for Neu­roimag­ing at Uni­ver­s­ity Col­lege Lon­don pre­vi­ously stud­ied the role of a small ar­ea of the brain known as the hip­po­cam­pus be­lieved to be cru­cial for naviga­t­ion, mem­o­ry re­call and im­ag­in­ing fu­ture events. Now, the re­search­ers stud­ied how the hip­po­cam­pus rec­ords mem­o­ry. 

Researchers used a scan­ner that meas­ures changes in blood flow with­in the brain, to ex­am­ine brain ac­ti­vity as a vol­un­teer nav­i­gat­ed a vir­tu­al real­ity en­vi­ron­ment. The da­ta were then an­a­lysed by a com­put­er pro­gram.


When we move around, brain cells, or neu­rons, in the hip­po­cam­pus known as “place cells” ac­tivate to tell us where we are. 

Has­s­abis, Maguire and col­leagues used a scan­ner that meas­ures changes in blood flow with­in the brain, to ex­am­ine these cells’ ac­ti­vity as a vol­un­teer nav­i­gat­ed a vir­tu­al real­ity en­vi­ron­ment. The da­ta were then an­a­lysed by a com­put­er pro­gram de­vel­oped by Has­s­abis.

“Sur­pris­ingly, just by look­ing at the brain da­ta we could pre­dict ex­actly where they were in the vir­tu­al real­ity en­vi­ron­ment,” said Maguire. The study ap­peared March 12 in the re­search jour­nal Cur­rent Bi­ol­o­gy.

Ear­li­er stud­ies in rats in­di­cat­ed the hip­po­cam­pus rec­ords spa­tial mem­o­ries, or the con­cept of where we are. But an­i­mal stud­ies, which meas­ured ac­ti­vity at the lev­el of doz­ens of cells at most, im­plied there was no struc­ture to how these mem­o­ries are rec­orded.

The new work con­tra­dicts this idea. The key dif­fer­ence: the new study al­lowed a bigger-picture view through use of the brain scan­ning tech­nol­o­gy fMRI, or func­tion­al Mag­net­ic Res­o­nance Im­ag­ing, Maguire said. “By look­ing at ac­ti­vity over tens of thou­sands of neu­rons, we can see that there must be a func­tion­al struc­ture – a pat­tern – to how these mem­o­ries are en­cod­ed,” she ex­plained.

“Un­der­stand­ing how we as hu­mans rec­ord our mem­o­ries is crit­i­cal to help­ing us learn how in­forma­t­ion is pro­cessed in the hip­po­cam­pus and how our mem­o­ries are erod­ed by dis­eases such as Alzheimer’s,” added Has­s­abis. “It’s al­so a small step to­wards the idea of mind read­ing.” 

Maguire pre­vi­ously led a study in­to the brains of cab drivers who spend years man­da­tor­ily learn­ing the maze of Lon­don streets—in­forma­t­ion known in the pro­fes­sion as “The Knowl­edge.” 

She found that in these cab­bies, an ar­ea to the rear of the hip­po­cam­pus was en­larged, sug­gest­ing that this was the ar­ea in­volved in learn­ing loca­t­ion and di­rec­tion. In the new stu­dy, Has­s­abis, Maguire and col­leagues found that the pat­terns re­lat­ing to spa­tial mem­o­ry lie in this same ar­ea, sug­gest­ing that the rear of the hip­po­cam­pus helps rep­re­sent the lay­out of spa­tial en­vi­ron­ments.


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New research adds to mounting evidence that it’s possible to “read” memories just by looking at brain activity. Experimenters found that our notion of where we are is recorded in regular patterns, contrary to current scientific thinking. Demis Hassabis and Eleanor Maguire at the Wellcome Trust Centre for Neuroimaging at University College London previously studied the role of a small area of the brain known as the hippocampus believed to be crucial for navigation, memory recall and imagining future events. Now, the researchers studied how the hippocampus records memory. When we move around, brain cells, or neurons, known as “place cells” in the hippocampus activate to tell us where we are. Hassabis, Maguire and colleagues used a scanner that measures changes in blood flow within the brain, to examine these cell’s activity as a volunteer navigated a virtual reality environment. The data were then analysed by a computer program developed by Hassabis. “Surprisingly, just by looking at the brain data we could predict exactly where they were in the virtual reality environment,” said Maguire. The study appeared March 12 in the research journal Current Biology, Earlier studies in rats indicated the hippocampus records spatial memories, or the concept of where we are. But animal studies, which measured activity at the level of dozens of cells at most, implied there was no structure to how these memories are recorded. The new work contradicts this idea. The key difference: the new study allowed a bigger-picture view through the use the brain scanning technology fMRI, or functional Magnetic Resonance Imaging, Maguire said. “By looking at activity over tens of thousands of neurons, we can see that there must be a functional structure – a pattern – to how these memories are encoded,” she explained. “Understanding how we as humans record our memories is critical to helping us learn how information is processed in the hippocampus and how our memories are eroded by diseases such as Alzheimer’s,” added Hassabis. “It’s also a small step towards the idea of mind reading.” Maguire previously led a study into the brains of cab drivers who spend years mandatorily learning the maze of London streets—information known in the profession as “The Knowledge.” She found that in these cabbies, an area to the rear of the hippocampus was enlarged, suggesting that this was the area involved in learning location and direction. In the new study, Hassabis, Maguire and colleagues found that the patterns relating to spatial memory lie in this same area, suggesting that the rear of the hippocampus plays a key role in representing the layout of spatial environments.