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 theWellcome Trust Centre for Neuroimaging at University College Londonhope 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. “We can rest easy in terms of issues surrounding mind reading. This requires the person to be cooperative, and to train the algorithms we use many instances of a particular memory,” said Maguire. “It’s not that we can put someone in a brain scanner and suddenly read their thoughts. It’s quite an invovled process that’s at a very early stage.”
Though preliminary, the research raises questions about what may be possible with brain scanners in the future. Future advances in technology may make it possible to tell whether a person has ever been in a particular place, which could have enormous implications for the judicial system. Information from brain scans has already been used in court in India to help judge whether defendants are telling the truth or not. Demis Hassabis, who co-authored the study in the journal Current Biology, said: “The current techniques are a long way away from being able to do those kinds of things, though in the future maybe that will become more possible. Maybe we’re about 10 years away from doing that.”
“It might be useful to start having those kinds of ethical discussions in the near future in preparation of that,” he added.
Previous work in rats identified the hippocampus as a region of the brain that stores spatial memories. But experiments that measured the activity of handfuls of neurons in the animals’ brains suggested there was no predictable pattern in how those memories were stored. The discovery that spatial memories are encoded in a predictable way in our brains will give scientists confidence that other memories might be readable using brain scanners. In the near term, Maguire said the research will shed light on some of the most debilitating neurodegenerative diseases of old age. “By using techniques like this we’re learning more and more about how memories are laid down. If we can understand the processes involved in how you form and store and recollect memories, we can begin to understand how these pathological processes erode memories, and much further down the line, how we might help patients in a rehabilitation context,” she said. In a previous study, Maguire used brain scans to show that a brain region at the rear of the hippocampus known to be involved in learning directions and locations is enlarged in London taxi drivers.