Dynamic stimulation of visual cortex produces form vision in sighted and blind humans

A visual cortical prosthesis(VCP) has long been proposed as astrategy for
restoringuseful vision to the blind, under the assumptionthat visual
percepts of small spots of lightproduced withelectrical stimulation of
visual cortex (phosphenes) will combine into coherent percepts of visual
forms, like pixels on a video screen.We tested analternative strategy in
which shapes were traced on the surface of visual cortex by stimulating
electrodes in dynamic sequence. In both sighted and blind participants,
dynamic stimulation enabled accurate recognition of letter shapespredicted
by the brain’s spatial map ofthe visual world.Forms could be presented and
recognized rapidlyby blind participants, up to 86 forms per minute.These
findings demonstrate that a brainprosthetic can produce coherent
perceptsof visualforms.