the first technology to do this was developed in the 1920s by german psychiatrist, hans berger. he invented an instrument he called the electroeephalogram, or eeg. the device measures the brais electric activity through the skull and represents it as complicated lines oa graph. however, decoding these brainwave patterns is an immense challenge, especially when the goal is to control complex movement. - imagine that those signals coming from your hand to control that were not coming from your hand, but from your brain. and now you don't know what makes your brain cells active, so how can you relate what your brain cells are doing to that motion? and we dn't know whether anybody could ever learn to do it. - [angel] with braingate, john took the next very difficult step of deciphering a person's mental intention to move their body. - [john] so, the first thing we have to do, is we have to go to a place in the brain that has those signals. then we need to be able to sample the activity in the brain. - [angel] this involves surgically implanting tiny electrodes in the region of the b