currentsinbiology: Brain’s GPS Has a Buddy System To be successful as a social animal, you nee
currentsinbiology: Brain’s GPS Has a Buddy System To be successful as a social animal, you need to know where you stand relative to others. Brain cells that perform precisely this function–locating the ‘self’ and others in space–have now been identified. In rats, the same brain area that stores the animal’s own location also maps the movements of other rats. Sometimes these representations are processed jointly by the same cells, depending on a rat’s goals and actions. This discovery, from Japan’s RIKEN Brain Science Institute, deepens our understanding of the hippocampus and its role as the brain’s positioning system. It has been known for some time that the hippocampus maintains a mental map of space–in fact, the 2014 Nobel Prize in Physiology or Medicine was awarded precisely for this research. ‘Place cells’ and ‘grid cells’ in the hippocampus register the location of the brain’s owner in its environment, but until now, little was known about how the movements of others are tracked in the brain. Researchers put this to the test by observing the activity of hippocampal neurons in one rat (the ‘self’) watching another rat (the ‘other’) go through a simple T-maze. The self’s neurons registered what the other was doing and changed their responses based on the self’s location and subsequent actions. This study was published on January 11 in Science, which also contains a report of similar location awareness in the brains of bats. Hippocampal place cells light up only for certain locations in the environment, and some of these cells clearly preferred the location of the other rat. Besides activation to places, the timing of neural activity in the hippocampus is also important. A ‘refresh rate’ of around 8 Hz dictates how often neurons update their activity, a phenomenon called theta-cycle phase precession. Three-quarters of cells updated based on the other’s location, not only the self’s. “It is very interesting that the trajectories of the other, that is, the past, current, and future positions of the observed rat, are compressively represented in 100-millisecond cycles in the hippocampus,” says Shigeyoshi Fujisawa, research group leader at the RIKEN Brain Science Institute. “Spatial representations of self and other in the hippocampus” by Teruko Danjo, Taro Toyoizumi, and Shigeyoshi Fujisawa in Science. Published online January 12 2018 doi:10.1126/science.aao3898 These are the four types of spatial models for the hippocampus that are proposed in this paper.NeuroscienceNews.com image is credited to RIKEN. -- source link
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