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The BCI Briefing

Motor · Decoding & AI

High-performance brain-to-text communication via handwriting

Authors
Willett FR … Shenoy KV5 authors
Institution
Stanford University
Publication
NatureNature 2021;593(7858):249–254 · 12 May 2021
Status
Primary source

The 60-second view

What problem?
Point-and-click typing capped BCI communication well below everyday typing speeds.
What did they do?
Decoded attempted handwriting movements from motor cortex into text in real time with a recurrent neural network.
What changed?
Roughly doubled the best previous BCI typing rate and showed that complex, fast movements can be easier to decode than simple ones.
Why does it matter?
It changed the field's intuition about what to decode: rich, time-varying movements carry more information than cursor trajectories.

Method

Participants
One person with hand paralysis from spinal cord injury
Interface
Two intracortical microelectrode arrays in motor cortex
Signal
Intracortical spiking activity
Task
Attempted handwriting of letters and sentences
Decoder
Recurrent neural network, with optional autocorrect

Results

90 characters/min
Typing rate
94.1%
Raw accuracy, online
>99%
Accuracy with autocorrect, offline

Strength of evidencePeer reviewed, one participant; dataset publicly released.

Figures are quoted from the published abstract and were checked on 3 Oct 2026.

Limitations

  • One participant.
  • Requires periodic decoder recalibration.

What this could enable

Decoding of rapid, dexterous movement years after paralysis, and the sequence-decoding methods later used for speech.

Primary source

  1. 01

    Willett FR et al. Nature 2021;593(7858):249–254 (opens in a new tab)

    Peer reviewedNature12 May 2021Checked against source 3 Oct 2026

    DOI 10.1038/s41586-021-03506-2