At University College London, scientists are using an fMRI machine to identify the memories that people are bringing up. By first playing three different videos to human subjects and then asking them to recall them in turn while inside an fMRI, the researchers were able to use a computer algorithm to identify which video was being recalled.
Professor Eleanor Maguire led this Wellcome Trust-funded study, an extension of work published last year which showed how spatial memories – in that case, where a volunteer was standing in a virtual reality room – are recorded in regular patterns of activity in the hippocampus, the area of the brain responsible for learning and memory.
“In our previous experiment, we were looking at basic memories, at someone’s location in an environment,” said Professor 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.”
Although a whole network of brain areas support memory, the researchers focused their study on the medial temporal lobe, an area deep within the brain believed to be most heavily involved in episodic memory. It includes the hippocampus – an area which Professor Maguire and colleagues have studied extensively in the past.
They found that the key areas involved in recording the memories were the hippocampus and its immediate neighbours. However, the computer algorithm performed best when analysing activity in the hippocampus itself, suggesting that this is the most important region for recording episodic memories. In particular, three areas of the hippocampus – the rear right and the front left and front right areas – seemed to be involved consistently across all participants. The rear right area had been implicated in the earlier study, further enforcing the idea that this is where spatial information is recorded. However, it is still not clear what role the front two regions play.
Here are the three videos study participants were asked to memorize:
Full story: Traces of the past: computer algorithm ‘reads’ memories …
Abstract in Current Biology: Decoding Individual Episodic Memory Traces in the Human Hippocampus…
Image: Siemens Magnetom Verio 3T open bore MRI
