As our Technology Quarterly in this issue explains, the pace of research into BCIs and the scale of its ambition are increasing.
Both America's armed forces and Silicon Valley are starting to focus on the brain.
Facebook dreams of thought-to-text typing.
Kernel, a startup, has $100m to spend on neurotechnology.
Elon Musk has formed a firm called Neuralink; he thinks that, if humanity is to survive the advent of artificial intelligence, it needs an upgrade.
Entrepreneurs envisage a world in which people can communicate telepathically, with each other and with machines, or acquire superhuman abilities, such as hearing at very high frequencies.
These powers, if they ever materialise, are decades away.
But well before then, BCIs could open the door to remarkable new applications.
Imagine stimulating the visual cortex to help the blind, forging new neural connections in stroke victims or monitoring the brain for signs of depression.
By turning the firing of neurons into a resource to be harnessed, BCIs may change the idea of what it means to be human.
Taking medical BCIs out of the lab into clinical practice has proved very difficult.
The BrainGate system used by Mr Kochevar was developed more than ten years ago, but only a handful of people have tried it out.
Turning implants into consumer products is even harder to imagine.
The path to the mainstream is blocked by three formidable barriers—technological, scientific and commercial.