From Nature:
People have used mind control to change images on a video screen, a study reports. The volunteers, whose brains were wired up to a computer, enhanced one of two competing images of famous people or objects by changing firing rates in individual brain cells.
The research, by Moran Cerf from the California Institute of Technology in Pasadena and his colleagues, demonstrates how our brains, which are constantly bombarded with images, noise and smells, can, through conscious thought, select what stimuli to notice and what to ignore (see video). The research is particularly exciting, says neuroengineer John Donoghue of Brown University, “because it shows how we can now peer into the process of thinking at a level we have not been able to get at before”. Donoghue was responsible for the first successful transplantation of a chip into the motor cortex of a tetraplegic man, enabling him to move a computer cursor and manipulate a robotic arm with his mind.
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In the last six years or so they have shown that single neurons can fire when subjects recognise — or even imagine — just one particular person or object. They propose that activity in these neurons reflect the choices the brain is making about what sensory information it will consider further and what information it will neglect.
More here.