AANS Neurosurgeon | Volume 27, Number 2, 2018


The Brain’s GPS Depends on Visual Landmarks

In a recent study published in the journal Cell, researchers from the University of California, Los Angeles, found that space-mapping neurons have a strong dependence on what is being looked at when triangulating location — a finding that resolves a long-lasting neurological mystery. “This part of the brain, the hippocampus, has neurons that fire in specific places. If I’m walking around a room, some neurons fire near the door, others around the middle of the room and they all form a map of space in the brain,” said the director of a neurophysics center. “Where does this map come from? The classic idea was there are two possible mechanisms. One hypothesis is that neurons triangulate distances with respect to visual landmarks. However, it was commonly believed that hippocampal neural responses do not depend on which landmark the rat was looking at, a long standing paradox. The other idea is that neurons are keeping track of the distances traveled by the subject, through the so called path-integration, though not directly tested.” Surprisingly, the team found that the neurons did signal for what landmark the rat was looking at, thus removing the 45-year-old paradox about whether the landmarks exert a causal influence on hippocampal directional responses. Further, careful experiments using virtual reality showed that the neural responses were neither abstract representations of space, as commonly thought, nor vestibular input driven path-integration signals. Instead, these responses were causally and predictably governed by visual landmarks. To read more about this study, click here.

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