Would it be possible to turn a human eye into a camera, by simply reading information sent to the brain by the optic nerves and recording the same as video to be played back later? This may sound something out of a sci-fi Hollywood movie, but researchers have already accomplished this at a very basic level.
Way back in 1999, a team of US scientists from the University of California at Berkeley performed an extraordinary experiment where they wired up a cat’s brain to a computer and recorded videos of what the animal was seeing.
The team used an array of electrodes embedded in the thalamus (which integrates all of the brain’s sensory input) of the cats and monitored activity of 177 brain cells that responded to light and dark in the cat's field of view. The cats were shown eight short movies, and their neuron firings were recorded. Using mathematical filters, the researchers decoded the signals to generate movies of what the cats saw and were able to reconstruct recognizable scenes and moving objects.
A similar experiment was accomplished with humans in 2008 at the Advanced Telecommunications Research (ATR) Computational Neuroscience Laboratories in Kyoto, Japan.
In the tests, scientists were able to reconstruct various images viewed by a person by analyzing changes in their cerebral blood flow using a functional magnetic resonance imaging (fMRI) machine. The test subjects were shown 400 random 10 x 10 pixel black-and-white images for a period of 12 seconds each. While the fMRI machine monitored the changes in brain activity, a computer crunched the data and learned to associate the various changes in brain activity with the different image designs.
Then, when the test subjects were shown a completely new set of images, such as the letters N-E-U-R-O-N, the system was able to reconstruct and display what the test subjects were viewing based solely on their brain activity.
Being able to tap directly into the brain and extract visual images may one day allow humans to control machines by thought alone. It is also conceivable that, in the future, it will be possible to record what one person sees, thinks or even dreams and play it back to someone else!
Read more about Brain–computer interface.