Neuroscientists at University College London have taken another step towards mind-reading. They have developed a computer algorithm which allows them to tell which of three short films a person is thinking about via a brain scan.
The research builds on work last year in which it was found that spatial memories – in that case, where a volunteer was standing in a virtual reality room – are recorded in the hippocampus.
"In our previous experiment, we were looking at basic memories, at someone’s location in an environment," said UCL professor Eleanor Maguire. "What is more interesting is to look at 'episodic' memories – the complex, everyday memories that include much more information on where we are, what we are doing and how we feel."
The researchers showed ten volunteers three simple films and asked them to memorise what they saw. The films all included a woman carrying out an everyday task in an urban street - posting a letter, throwing away a cup and collecting a bicycle. Each was seven seconds long.
The volunteers were then asked to remember each of the films whilst inside an fMRI scanner, which records brain activity by measuring changes in blood flow within the brain.
A computer algorithm then studied the patterns.
"The algorithm was able to predict correctly which of the three films the volunteer was recalling significantly above what would be expected by chance," says lead author Martin Chadwick. "This suggests that our memories are recorded in a regular pattern."
The team found that the computer algorithm worked best when analysing activity in the hippocampus itself, implying that this is the most important region for recording episodic memories.
In particular, three areas of the hippocampus seemed to be involved consistently across all participants. One had already been identified in the earlier study, but it's still not clear what role the other two play.