(Story submitted 7/6/2005)
What is the Matrix? In this case, it is a 64x64 array produced by linear decoding, that reconstructs spatiotemporal visual inputs from ensemble responses in the lateral geniculate nucleus (LGN) of sharp-eyed cats. From the responses of 177 brain cells, they were able to reconstruct time-varying natural scenes with recognizable moving objects.
In this 1999 study, Garett B. Stanley, Fei F. Li and Yang Dan have literally jacked into the mind of a cat. Multiple cells in the LGN of anesthetized cats were recorded simultaneously with multielectrodes. The spike trains of the neurons were binned according to the frame rate of the stimulus (32 Hz for movies, 128 Hz for white noise) and converted to firing rate signals. They recorded the responses of the cells to multiple repeats of eight short movies, and these data were used for subsequent analyses. The geniculate cells were well driven by the movie stimuli, as indicated by their mean firing rates, which were higher during movie presentation than in the absence of visual stimuli.
When science fiction fans think about examples in which one person can directly experience (or see) and record the internal experience of another person, they usually think about Neuromancer, the 1984 novel by William Gibson. In the novel, he refers to simstim:
Cowboys didn't get into simstim, he thought, because it was basically a meat toy. He knew that ... the cyberspace matrix was actually a drastic simplification of the human sensorium, at least in terms of presentation, but simstim itself struck him as a gratuitous multiplication of flesh input.
The cyberspace matrix, according to the book, "has its roots in primitive arcade games... in early graphics programs and military experimentation with cranial jacks."
As far as I know, the first science fiction author to describe a mechanical process for viewing and recording the thoughts of another person (as opposed to a purely mental "ability" - namely, telepathy) was Cordwainer Smith. In his 1958 story No, No, Not Rogov!, he writes about an espionage machine that can let one person see the thoughts of another:
He had then turned away from the reception of pure thought
to the reception of visual and auditory images. Where the nerve-ends reached
the brain itself, he had managed over the years to distinguish whole packets of
microphenomena, and on some of these he had managed
to get a fix.
(Read more about the espionage machine)
Read more from the original paper (Reconstruction of Natural Scenes from Ensemble Responses in the Lateral Geniculate Nucleus - pdf); original post at Extracting video from cat brains. Thanks to alert reader Justin Kennedy for pointing this story out.