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What the cat saw

作者:南蜂斌    发布时间:2019-03-07 06:19:06    

By Marina Chicurel BY EAVESDROPPING on neurons in the brains of cats, scientists have made videos of what the cats actually see. It confirms that scientists’ understanding of the language of certain visual neurons is bang on target. Most neuroscientists study vision from the way neurons respond to different images. This strategy has provided the foundations of our understanding of perception. But the ultimate test is to apply the opposite approach—to reconstruct videos of the ouside world from measurements of the neurons’ behaviour. To do this, Yang Dan and her colleagues from the University of California at Berkeley anaesthetised cats and used electrodes to measure the activity of 177 neurons in their lateral geniculate nuclei—the first stop in the brain for incoming signals from the eyes. The cats were shown pictures such as the view from a camera panning across a forest. The team reconstructed scenes the cats saw from measurements of neuron activity, via mathematical equations describing the responses of each cell and their interactions with other cells. Results from earlier studies suggested 20 to 30 neurons respond to each point in the field of vision. And sure enough, the reconstructed scenes were clearest when each point was recreated from a similar number of neurons (The Journal of Neuroscience, vol 19, p 8036). “The majority of what we know about vision has been determined by looking at what a single neuron does,” says team leader Garrett Stanley of Harvard University. “This work looks at groups of neurons and how they might encode information about the outside world.” Ehud Kaplan, a neuroscientist at the Mount Sinai School of Medicine in New York, says the experiment is technically impressive. “They crossed all the t’s and dotted all the i’s.” He hopes that future studies will shed light on how the brain makes sense of these scenes. “Our ultimate goal is to comprehend how we understand the world,

 

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