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State of the field

Neural Interfaces & BCIs

Reading from and writing to the nervous system to restore speech, movement and sensation.

Maturity
Translational

Overview reviewed

Where things stand

Neural interfaces cover a spectrum from established therapies to experimental brain–computer interfaces (BCIs). Cochlear implants and deep brain stimulation for Parkinson's disease and essential tremor are long-established. Implanted BCIs that decode intention, by contrast, have mostly been tested in small early-feasibility studies with a handful of participants each.

Recent progress

  • Speech. In 2023, two groups reported speech neuroprostheses for people with paralysis: a Stanford team decoded attempted speech to text at 62 words per minute (Willett et al., Nature), and a UCSF team decoded speech to text and a talking avatar (Metzger et al., Nature).
  • Walking. A "digital bridge" linking a brain implant to spinal cord stimulation let a man with chronic tetraplegia walk more naturally (Lorach et al., Nature, 2023).
  • Commercial entrants. Several companies, including Neuralink, Synchron and Precision Neuroscience, have implanted devices in human participants in early studies, using different approaches: high-channel-count threads, an endovascular stent electrode, and thin-film surface arrays.

What is contested

Results come from very few participants, and long-term signal stability, device longevity and day-to-day usability remain open. Company announcements often come before peer-reviewed data, so entries here distinguish published results from press releases.

What to watch

Movement from feasibility to pivotal trials, multi-year durability data, and the first regulatory approvals for communication BCIs.

Milestones

  1. 1924First human EEG. Hans Berger records the electrical activity of the human brain through the scalp. He publishes the work in 1929, founding electroencephalography.
  2. 2005Optogenetics in neurons. Neurons expressing the algal light-gated channel channelrhodopsin-2 are shown to fire on command with millisecond flashes of light, giving researchers precise control over cell voltage.
  3. 2006A person controls a computer cursor with thought. In the BrainGate trial, a man with tetraplegia uses an implanted microelectrode array to control a computer cursor and open simulated email. This is an early demonstration of an implanted brain–computer interface.
  4. 2019Neurons form synapses with brain tumours. Two groups report in *Nature* that glioma cells receive synaptic input from neurons and that neural activity drives tumour growth, founding the field of cancer neuroscience.
  5. 2023Brain–spine interface restores natural walking. A wireless "digital bridge" between brain implants and spinal cord stimulation lets a man with chronic tetraplegia stand, walk and climb stairs by thinking about moving.
  6. 2023Speech neuroprostheses reach conversational rates. Two teams decode attempted speech from cortical implants in people with paralysis, producing text at 62 and 78 words per minute, as well as a synthesized voice and a digital avatar.

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