By Ian Sample
Collections of brain cells in the hippocampus encoded the person’s location
Scientists have used brain scans to read people’s memories and work out where they were as they wandered around a virtual building.
The landmark study by British researchers demonstrates that powerful imaging technology is increasingly able to extract our innermost thoughts.
The feat prompted the team to call for an ethical debate on how brain imaging may be used in the future, and what safeguards can be put in place to protect people’s privacy.
The study was part of an investigation aimed at learning how memories are created, stored and recalled in a part of the brain called the hippocampus.
By understanding the processes at work in the brain, scientists at the Wellcome Trust Centre for Neuroimaging at University College London hope to get a better grasp of how Alzheimer’s disease and strokes can destroy our memories and find ways to rehabilitate patients.
In the study, volunteers donned a virtual reality headset and were asked to make their way between four locations in a virtual building. Throughout the task, their brain activity was monitored using a technique called functional magnetic resonance imaging (fMRI).
Eleanor Maguire and Demis Hassabis then used a computer program to look for patterns in the volunteers’ brain activity as they stood on virtual rugs in the four different locations. They found that particular collections of brain cells encoded the person’s location in the virtual world, and they were able to use this to predict where each volunteer was standing.
“Remarkably, using this technology, we found we could accurately predict the position of an individual within this virtual environment, solely from the pattern of activity in their hippocampus,” said Maguire.
“We could predict what memories a person was recalling, in this case the memory for their location in space,” she added.
The study overturns neuroscientists’ assumption that memories of our surroundings are encoded in the brain in an unpredictable way. The latest research suggests that this is not the case, and that the information is stored in our neurons in a very structured way that can be picked up by scanners.
The scientists could not tell where somebody was from a single brain scan. Instead, they had to perform several scans of volunteers in each location. Only afterwards were they able to find differences in brain activity that betrayed the person’s location.