Brain Implants Let Paralyzed People Type Nearly as Fast as Smartphone Users

It’s hard to picture a keyboard layout other than the one we know best. From laptops to smartphones, it’s an integral part of our digital lives.

Scientists at Massachusetts General Hospital have now restored the ability to communicate by keyboard to two people with paralysis—using their thoughts alone.

Both people already had brain implants that could record their minds’ electrical chatter. The new system translated brain signals in real time as each person imagined finger movements. The system then accurately predicted the character they were trying to type.

The system learned to translate brain activity to physical intent after just 30 sentences. Typing speeds reached 22 words per minute with few errors, nearly matching speeds of able-bodied smartphone users.

“To our knowledge, this system provides the fastest… [brain implant] communication method reported to date based on decoding from hand motor cortex,” wrote the team.

The participants are part of the BrainGate2 clinical trial, a pioneering effort to restore communication and movement by decoding neural signals in people who have lost the use of all four limbs and the torso. One of the participants previously used the implants to translate his inner thoughts into text, but with mixed success.

Controlling a digital keyboard is far more intuitive and familiar, which makes it easier to grasp. Once a person learns to use the system, they don’t have to look at the keyboard, giving their eyes a break as they type with their minds. It also allows users full control of when, or when not, to share their thoughts, preventing accidental leakage of private musings onto a screen or broadcasted with AI-generated speech.

All Hands on Deck

Parts of the brain hum with electrical activity before we speak. Over the past decade, brain implants—microelectrodes that listen in and decode signals—have translated these seemingly chaotic buzzes into text or speech, allowing paralyzed people to regain the ability to communicate.

Methods vary. Some hardware takes the form of wafer-thin disks sitting on top of the brain and gathering signals from vast regions; other devices are inserted into the brain for more targeted recordings.

These systems are life changing. In a recent example, an implant translated the neural activity controlling a man with ALS’s vocal muscles. With just a second’s delay, the system generated coherent sentences with intonation, allowing him to sing with an artificial voice. Another device turned a paralyzed woman’s thoughts into speech with nearly no delay, so she could hold a conversation without frustrating halts. People have also benefited from a method that uses the neural signals behind handwriting for brain-to-text communication.

Brain implants aren’t purely experimental anymore: China recently approved a setup allowing people with paralysis to control a robotic hand. It’s the first such device available outside of clinical trials.

Perhaps the most widely used clinical solution is eye-tracking. Here, patients move their eyes to focus on individual letters, one at a time, on a custom digital keyboard. But the pace is agonizingly slow and prone to error. And prolonged screen time strains the eyes, making extended conversations difficult.

“Those systems take far too long for many users,” said study author Daniel Rubin in a press release, causing them to abandon the technology.

Tapping Away

For people who already know how to type, the standard keyboard layout—known as QWERTY—feels familiar and comfortable. Fingers stretch to hit letters in the upper row, tap directly down for ones in the middle, and curl into a loose claw to hit bottom letters and punctuation.