A new kind of brain-computer interface (BCI) that uses neural implants the size of a grain of sand to record brain activity has been proven effective in rats — and one day, thousands of the “neurograins” could help you control machines with your mind.

Mind readers: BCIs are devices (usually electrodes implanted in the skull) that translate electrical signals from brain cells into commands for machines. They can allow paralyzed people to “speak” again, control robots, type with their minds, and even regain control of their own limbs.

Most of today’s interfaces can listen to just a few hundred neurons — but there are approximately 86 billion neurons in the brain. If we could monitor more neurons, in more places in the brain, it could radically upgrade what’s possible with mind-controlled tech.