New Scientist reports : Scans of the part of the brain responsible for memory have for the first time been used to detect a person’s location in a virtual environment. Using functional MRI (fMRI), researchers decoded the approximate location of several people as they navigated through virtual rooms. The work is continuing to use scans and more precise scans to discern what someone was doing, where they are or were and where they plan to go.
This finding suggests that more detailed mind-reading, such detecting as memories of a summer holiday, might eventually be possible, says Eleanor Maguire, a neuroscientist at University College London.
“This is a very interesting case because it was previously believed impossible to decode [spatial] information,” says John-Dylan Haynes, a neuroscientist at the Bernstein Center for Computational Neuroscience in Berlin, Germany.
“There must be some hidden structure in the spatial organisation of cells with activity related to each of the places in the environment,” agrees Edvard Moser, a neuroscientist at the Norwegian University of Science and Technology in Trondheim.
Decoding Neuronal Ensembles in the Human Hippocampus
The hippocampus underpins our ability to navigate, to form and recollect memories, and to imagine future experiences. How activity across millions of hippocampal neurons supports these functions is a fundamental question in neuroscience, wherein the size, sparseness, and organization of the hippocampal neural code are debated.Here, by using multivariate pattern classification and high spatial resolution functional MRI, we decoded activity across the population of neurons in the human medial temporal lobe while participants navigated in a virtual reality environment. Remarkably, we could accurately predict the position of an individual within this environment solely from the pattern of activity in his hippocampus even when visual input and task were held constant. Moreover, we observed a dissociation between responses in the hippocampus and parahippocampal gyrus, suggesting that they play differing roles in navigation.These results show that highly abstracted representations of space are expressed in the human hippocampus. Furthermore, our findings have implications for understanding the hippocampal population code and suggest that, contrary to current consensus, neuronal ensembles representing place memories must be large and have an anisotropic structure.
Reading more precise locations or other kinds of memories could be difficult, because fMRI resolves the activity of thousands of neurons at a time, Haynes says. “One day a new imaging technique could come along and you’d be at the right place to decode even in these challenging cases,” he adds.
However, Maguire isn’t waiting for new technologies. Her team is already looking into the possibility of reading more vivid memories of events and planned movements. “We’ve done some work about how the hippocampus is involved in planning the future – where you’re going and what you’re doing.”