Seeing may depend less on our eyes than we thought.

When you identify an object's shape, a particular part of your brain called the LOtv "lights up". At first this area was thought to be purely visual, but several years ago Amir Amedi, now at Harvard Medical School, showed that touch could also activate it. Now Amedi and his team have shown that even "hearing" a shape can activate the area.

They taught seven sighted volunteers to use a device called The vOICe, which converts visual details into sound, using pitch to represent up and down, and volume to reflect brightness. The team then performed fMRI scans of the volunteers' brains, plus those of two expert blind users of the device, as they listened to these soundscapes. They also scanned seven controls, who had been taught to associate specific soundscapes with certain shapes, but not how to interpret them.

The LOtv only lit up in the skilled users who were actually decoding the soundscapes, not in those just associating them with shapes (Nature Neuroscience, DOI: 10.1038/nn1912). "It was a huge activation," says Amedi. "I think they're seeing."

Sounds made by the objects, such as the sound of a bouncing ball, produced no such effect. The finding suggests the brain may not care about the mode of input as much as people assumed. The LOtv is clearly driven by the presence of shape, but it doesn't care whether the input is visual, tactile or auditory, Amedi says. He hopes The vOICe might one day help blind people "see".