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A Cat's Eye Marvel
by Leander Kahney

In a dramatic demonstration of mind reading, neuroscientists have created videos of what a cat sees by using electrodes implanted in the animal's brain.

Garrett Stanley of Harvard, and Fei Li and Yang Dan of the University of California, Berkeley, were able to reconstruct in startling detail scenes flashed before a cat's eyes.

The reconstructed scenes clearly demonstrate the scientist's ability to decode the language of the cat's visual system.

The researchers attached electrodes to 177 cells in an anesthetized cat's thalamus, a region of the brain falling about half-way in the visual processing pathway.

Having recorded patterns of firing as various scenes were flashed before the cat's eyes, the team was able to reconstruct very closely what the animal saw, which varied from people's faces to scenes of a dark forest.

The research was applauded by other neuroscientists.

"The demonstration that you can reconstruct a movie from the multiple cells in the thalamus is an important step in our understanding of how signals are represented in the activity of populations of cells," said Fred Rieke, an assistant professor of physiology and biophysics at the University of Washington.

Stanley, an assistant professor of biomedical engineering, said the research provides clues about how prosthetics may one day be wired into the mammalian nervous system. By understanding the language of the brain, scientists will be able to create devices that talk to it, he said.

"Trying to understand how the brain codes information leads to the possibility of replacing parts of the nervous system with an artificial device," he said.

Stanley predicted that in the next couple of decades, as more and more of the neural code is decoded, brain interfaces may start to appear.

But he cautioned it may take a lot longer. He noted that the team also recorded the activity of cells higher up in the cat's visual pathway -- in the visual cortex -- but the results were not as startling because of the greater complexity of the cells.

"So little is understood about thoughts, perceptions, dreams, it's impossible to predict how much progress we'll make in understanding them," he said.

However, Ken Miller, as associate professor at the University of California, San Francisco, said researchers around the world are using similar techniques to decode higher brain functions.

"These methods could be applied to further up the visual pathway," he said. "It will become more difficult ... but it's a promising direction."

The experiments were reported in the September issue of the Journal of Neuroscience.

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