Friday, October 8, 1999

Computer uses cat's brain to see

Scientists have literally seen the world through cat's eyes

By BBC News Online Science Editor Dr David Whitehouse

In what is bound to become a much debated and highly controversial experiment, a team of US scientists have wired a computer to a cat's brain and created videos of what the animal was seeing.

According to a paper published in the Journal of Neuroscience, Yang Dan, Garret Stanley and Fei Li of the University of California at Berkeley have been able to "reconstruct natural scenes with recognizable moving objects."

The researchers attached electrodes to 177 cells in the so-called thalamus region of the cat's brain and monitored their activity.

The thalamus is connected directly to the cat's eyes via the optic nerve. Each of its cells is programmed to respond to certain features in the cat's field of view. Some cells "fire" when they record an edge in the cat's vision, others when they see lines at certain angles, etc. This way the cat's brain acquires the information it needs to reconstruct an image.

Recognisable objects

The scientists recorded the patterns of firing from the cells in a computer. They then used a technique they describe as a "linear decoding technique" to reconstruct an image.

To their amazement they say they saw natural scenes with recognisable objects such as people's faces. They had literally seen the world through cat's eyes.

Other scientists have hailed this as an important step in our understanding of how signals are represented and processed in the brain.

It is research that has enormous implications.

Artificial brain extensions

It could prove a breakthrough in the hoped-for ability to wire artificial limbs directly into the brain. More amazingly, it could lead to artificial brain extensions.

By understanding how information can be presented to the brain, some day, scientists may be able to build devices that interface directly with the brain, providing access to extra data storage or processing power or the ability to control devices just by thinking about them.

One of the scientists behind this current breakthrough, Garret Stanley, now working at Harvard University, has already predicted machines with brain interfaces.

Such revolutionary devices should not be expected in the very near future. They will require decoding information from elsewhere in the brain looking at signals that are far more complicated than those decoded from the cat's thalamus but, in a way, the principle has been demonstrated.