Cited by 969EEG and Brain-Computer InterfacesNeuroscience and Neural EngineeringGaze Tracking and Assistive Technology

High-performance brain-to-text communication via handwriting

Open access
Willett, Francis R., Avansino, Donald T., Hochberg, Leigh R., Henderson, Jaimie M., Shenoy, Krishna V.·2021·Nature

Published version of a preprint

Abstract

Brain-computer interfaces (BCIs) can restore communication to people who have lost the ability to move or speak. So far, a major focus of BCI research has been on restoring gross motor skills, such as reaching and grasping 1-5 or point-and-click typing with a computer cursor 6,7. However, rapid sequences of highly dexterous behaviours, such as handwriting or touch typing, might enable faster rates of communication. Here we developed an intracortical BCI that decodes attempted handwriting movements from neural activity in the motor cortex and translates it to text in real time, using a recurrent neural network decoding approach. With this BCI, our study participant, whose hand was paralysed from spinal cord injury, achieved typing speeds of 90 characters per minute with 94.1% raw accuracy online, and greater than 99% accuracy offline with a general-purpose autocorrect. To our knowledge, these typing speeds exceed those reported for any other BCI, and are comparable to typical smartphone typing speeds of individuals in the age group of our participant (115 characters per minute)8. Finally, theoretical considerations explain why temporally complex movements, such as handwriting, may be fundamentally easier to decode than point-to-point movements. Our results open a new approach for BCIs and demonstrate the feasibility of accurately decoding rapid, dexterous movements years after paralysis.

Integrity signals

Registry

Crossref · 10.1038/s41586-021-03506-2

Cites

59 of 59 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

32 of 39 cited sources checked · 18 supported · 1 flagged · accuracy not yet measured

  • Premisecitation

    In parameter optimization, cursor gain is raised to increase typing speed until decoding errors make the cursor uncontrollable.

    “During parameter optimization, the cursor gain is increased so as to increase typing rate, until the cursor moves so quickly that it becomes uncontrollable due to decoding errors22.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [22] Willett, F. R. et al. Signal-independent noise in intracortical brain–computer interfaces causes movement time properties inconsistent with Fitts’ law. J. Neural Eng. 14, 026010 (2017). source

      The Results section, “Effect of gain on movement time” (page unavailable), reports that increasing gain initially shortened target-acquisition time, but higher gains made cursor movements fast, inaccurate, and uncontrollable around targets. The paper relates this difficulty to decoding noise, but it studies cursor target acquisition, not typing rate, and does not describe the claimed typing-speed optimization procedure. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
  • Premisecitation

    Decoding accuracy is the main factor limiting the speed of point-and-click BCIs.

    “The speed of point-and-click BCIs is limited primarily by decoding accuracy.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [22] Willett, F. R. et al. Signal-independent noise in intracortical brain–computer interfaces causes movement time properties inconsistent with Fitts’ law. J. Neural Eng. 14, 026010 (2017). source

      The Results (Effect of gain on movement time; page unavailable) report that increasing cursor speed made movements fast but inaccurate, and the Introduction identifies signal-independent decoding noise as the root cause of the movement-time properties observed. This supports a speed–accuracy constraint in the intracortical cursor systems studied, but not the broader claim that decoding accuracy is the primary speed limit for point-and-click BCIs generally. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • Premisecitation

    EEG spellers based on oddball potentials or motor imagery usually achieve 1-5 characters per minute.

    “EEG spellers based on oddball potentials or motor imagery typically achieve 1–5 characters per minute28–32.”
    Quote in the paperSubstantial claim5 of 5 sources checked
    • cites [28] Vansteensel, M. J. et al. Fully implanted brain–computer interface in a locked-in patient with ALS. N. Engl. J. Med. 375, 2060–2066 (2016). source

      The Results section, “Communication and Independent Home Use” (page unavailable), reports spelling times for one patient using a fully implanted interface. Our copy does not give a typical rate for EEG spellers based on oddball potentials or motor imagery; searches for those methods and their characters-per-minute rates found no such passage. (LLM, conf=0.76)

      Experimental — accuracy not yet measured
    • cites [29] Nijboer, F. et al. A P300-based brain–computer interface for people with amyotrophic lateral sclerosis. Clin. Neurophysiol. 119, 1909–1916 (2008). source

      The Results report 1.2 and 2.1 selections per minute for the study’s P300 speller, which uses an oddball paradigm (Introduction). This supports the stated range for this speller in people with ALS, but the paper does not establish that EEG spellers generally achieve that rate or provide a rate for motor-imagery spellers. Page numbers were not available in our copy. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [30] Townsend, G. et al. A novel P300-based brain–computer interface stimulus presentation paradigm: moving beyond rows and columns. Clin. Neurophysiol. 121, 1109–1120 (2010). source

      The Discussion (§4.2; page unavailable) reports 4.10 selections/min for a previously studied P300 speller and 4.36 selections/min for this paper’s checkerboard P300 paradigm, both within the claimed range. It does not establish that 1–5 characters/min is typical across EEG spellers or report a rate for motor-imagery spellers. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
    • cites [31] McCane, L. M. et al. P300-based brain–computer interface (BCI) event-related potentials (ERPs): people with amyotrophic lateral sclerosis (ALS) vs. age-matched controls. Clin. Neurophysiol. 126, 2124–2131 (2015). source

      The Introduction (page unavailable) identifies the P300 speller as an oddball-response system that provides slow communication. The Methods describe a characters-per-minute measure, and the Results report communication rates for this study, but the passages do not state that EEG spellers typically achieve 1–5 characters per minute or address motor-imagery spellers. (LLM, conf=0.77)

      Experimental — accuracy not yet measured
    • cites [32] Wolpaw, J. R. et al. Independent home use of a brain–computer interface by people with amyotrophic lateral sclerosis. Neurology 91, e258–e267 (2018). source

      The Results report an average of 2.9 (±1.3 SD) selections per minute for BCI applications used by people with ALS, within the claimed numerical range. The paper does not establish a typical rate of 1–5 characters per minute across EEG spellers based on oddball potentials or motor imagery; selections are also not necessarily characters. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
  • Premisecitation

    Among intracortical BCIs, 2D cursor point-and-click typing has been the best performer, reaching at most 40 characters per minute.

    “For intracortical BCIs, the highest performing method has been point-and-click typing with a 2D computer cursor, peaking at 40 characters per minute 7”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [7] Pandarinath, C. et al. High performance communication by people with paralysis using an intracortical brain–computer interface. eLife 6, e18554 (2017). source

      The Introduction describes two-dimensional cursor control with click selection, and the Results say this study outperformed previous BCIs tested with people with motor impairment. The Results report T5’s average typing rate as 39.2 correct characters per minute, approximately 40, but do not identify 40 as a peak or an upper limit. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
  • Premisecitation

    Before this work, the best free typing rate for an intracortical BCI was 24.4 correct characters per minute.

    “The prior state-of-the-art for free typing in intracortical BCIs was 24.4 correct characters per minute 7.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [7] Pandarinath, C. et al. High performance communication by people with paralysis using an intracortical brain–computer interface. eLife 6, e18554 (2017). source
  • May combine two claims. 20
  • Classified as probably not a substantial claim. 8
  • May combine two claims.

    Interpretationown data

    Those autocorrected error rates are similar to state-of-the-art speech recognition systems, which have word error rates of 4-5%, and fall within a usable range.

    “which is comparable to state-of-the-art speech recognition systems (e.g. word error rates of 4–5% 14,15), putting it well within the range of usability.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [14] Xiong, W. et al. The Microsoft 2017 Conversational Speech Recognition System. Preprint at https://arxiv.org/abs/1708.06073 (2017). source

      The Conclusions (p. 4) identify 6.2% as the state-of-the-art word error rate on the Switchboard test data, not 4–5%. The paper does not assess whether an error rate is usable; the citing sentence presents usability as its own inference. (LLM, conf=0.88)

      Checked by a reasoning model — may be wrong.

      Experimental — accuracy not yet measured
    • cites [15] He, Y. et al. Streaming end-to-end speech recognition for mobile devices. In 2019 IEEE International Conference on Acoustics, Speech and Signal Processing 6381–6385 (2019). source
  • Classified as probably not a substantial claim.

    Premisecitation

    Earlier intracortical studies found that after paralysis, motor cortex still encodes intended reaching, grasping, and cursor movements.

    “Prior BCI studies have shown that the motor intention for gross motor skills, such as reaching, grasping or moving a computer cursor, remains neurally encoded in motor cortex after paralysis1–7.”
    Quote in the paperSubstantial claim6 of 7 sources checked
    • cites [1] Hochberg, L. R. et al. Reach and grasp by people with tetraplegia using a neurally controlled robotic arm. Nature 485, 372–375 (2012). source
    • cites [2] Collinger, J. L. et al. High-performance neuroprosthetic control by an individual with tetraplegia. Lancet 381, 557–564 (2013). source
    • cites [3] Aflalo, T. et al. Neurophysiology. Decoding motor imagery from the posterior parietal cortex of a tetraplegic human. Science 348, 906–910 (2015). source

      The passage comparing this study with previous human M1 recordings (indexed section labeled Abstract; page unavailable) reports that those studies decoded movement trajectories, supporting the motor-cortex portion in part. This paper’s own recordings of imagined reaching, grasping, and cursor control were from the posterior parietal cortex of a tetraplegic participant, not motor cortex. It does not establish that the earlier motor-cortex studies demonstrated all three movements named in the claim. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites [4] Bouton, C. E. et al. Restoring cortical control of functional movement in a human with quadriplegia. Nature 533, 247–250 (2016). source
    • cites [5] Ajiboye, A. B. et al. Restoration of reaching and grasping movements through brain-controlled muscle stimulation in a person with tetraplegia: a proof-of-concept demonstration. Lancet 389, 1821–1830 (2017). source
    • cites [6] Jarosiewicz, B. et al. Virtual typing by people with tetraplegia using a self-calibrating intracortical brain–computer interface. Sci. Transl. Med. 7, 313ra179 (2015). source
    • cites [7] Pandarinath, C. et al. High performance communication by people with paralysis using an intracortical brain–computer interface. eLife 6, e18554 (2017). source

      The Discussion (page unavailable) reports that people with no limb movement controlled a cursor using an intracortical BCI, and that monkeys given a paralytic agent retained grasp-related cortical activity. Our copy does not establish the claimed post-paralysis encoding of intended reaching; its mention of reaching is in a reference title about primates. (LLM, conf=0.82)

      Experimental — accuracy not yet measured
  • Classified as probably not a substantial claim.

    Premisecitation

    Earlier work has shown that neural recordings are stable over short periods.

    “as might be expected from prior work showing short-term stability of neural recordings19–21.”
    Quote in the paperSubstantial claim3 of 3 sources checked
    • cites [19] Dickey, A. S., Suminski, A., Amit, Y. & Hatsopoulos, N. G. Single-unit stability using chronically implanted multielectrode arrays. J. Neurophysiol. 102, 1331–1339 (2009). source
    • cites [20] Eleryan, A. et al. Tracking single units in chronic, large scale, neural recordings for brain machine interface applications. Front. Neuroeng. 7, 23 (2014). source
    • cites [21] Downey, J. E., Schwed, N., Chase, S. M., Schwartz, A. B. & Collinger, J. L. Intracortical recording stability in human brain–computer interface users. J. Neural Eng. 15, 046016 (2018). source
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation

    Maximizing nearest-neighbor distance between movements could be used to design movement sets that are easier to classify.

    “More generally, using the principle of maximizing the nearest neighbor distance between movements, it should be possible to optimize a set of movements for ease of classification26.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [26] Cunningham, J. P., Yu, B. M., Gilja, V., Ryu, S. I. & Shenoy, K. V. Toward optimal target placement for neural prosthetic devices. J. Neurophysiol. 100, 3445–3457 (2008). source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Performance may vary across participants; in an earlier study, T5 had the best performance among three participants.

    “Variability in performance across participants is also a potential concern (in a prior study, T5 achieved the highest performance of 3 participants7).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [7] Pandarinath, C. et al. High performance communication by people with paralysis using an intracortical brain–computer interface. eLife 6, e18554 (2017). source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Speech-decoding BCIs show promise for rapid communication, but their accuracy and vocabulary size still need improvement for general-purpose use.

    “Recently, speech-decoding BCIs have shown exciting promise for restoring rapid communication (e.g. 34,16,17), but their accuracies and vocabulary sizes require further improvement to support general-purpose use.”
    Quote in the paperNot a substantial claim3 of 3 sources checked
    • cites [34] Mugler, E. M. et al. Direct classification of all American English phonemes using signals from functional speech motor cortex. J. Neural Eng. 11, 035015 (2014). source
    • cites [16] Anumanchipalli, G. K., Chartier, J. & Chang, E. F. Speech synthesis from neural decoding of spoken sentences. Nature 568, 493–498 (2019). source
    • cites [17] Makin, J. G., Moses, D. A. & Chang, E. F. Machine translation of cortical activity to text with an encoder-decoder framework. Nat. Neurosci. 23, 575–582 (2020). source
  • May combine two claims.

    Premisecitation

    EEG spellers using visually evoked potentials have reached 60 characters per minute but have usability drawbacks: they occupy the eyes, are usually not self-paced, and need flashing light panels.

    “EEG spellers that use visually evoked potentials have achieved speeds of 60 characters per minute 18, but have important usability limitations, as they tie up the eyes, are not typically self-paced, and require panels of flashing lights on a screen.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [18] Chen, X. et al. High-speed spelling with a noninvasive brain–computer interface. Proc. Natl Acad. Sci. USA 112, E6058–E6067 (2015). source
  • May combine two claims.

    Premisecitation

    Intracortical BCIs using 2D cursor movements allow more freedom but have not exceeded 40 correct characters per minute in people.

    “Intracortical BCIs based on 2D cursor movements give the user more freedom to look around and set their own pace of communication, but have yet to exceed 40 correct characters per minute in people7.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [7] Pandarinath, C. et al. High performance communication by people with paralysis using an intracortical brain–computer interface. eLife 6, e18554 (2017). source

      The Introduction describes continuous two-dimensional cursor control, and the Discussion describes the point-and-click interface as flexible. The Results report average copy-typing rates up to 39.2 correct characters per minute, but do not establish that no individual typing rate exceeded 40. The cited passages also do not establish the specific claim that users can look around while communicating. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • May combine two claims.

    Findingown data

    During attempted handwriting, the recorded neural activity looked strong and repeatable, but the timing of its peaks and valleys differed between trials, possibly because writing speed fluctuated.

    “The neural activity appeared to be strong and repeatable, although the timing of its peaks and valleys varied across trials, potentially due to fluctuations in writing speed.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    The neural patterns for individual characters were highly stable in the short term (mean correlation 0.85 for intervals of 7 days or less), and neural changes appeared to accumulate steadily and predictably.

    “We assessed the stability of the neural patterns associated with each character and found high short-term stability (mean correlation = 0.85 when 7 days apart or less), and neural changes that seemed to accumulate at a steady and predictable rate (Extended Data Fig. 4).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    A non-causal offline RNN trained on all available sentences achieved a 0.17% character error rate, suggesting a high performance ceiling, but it could not give letter-by-letter feedback.

    “Accuracy was extremely high in this regime (0.17% character error rate), indicating a high potential ceiling of performance, although this decoder would not be able to provide letter-by-letter feedback to the user.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    Linear decoding of pen tip velocity from trial-averaged neural activity produced recognizable letter shapes, indicating that pen tip velocity is strongly represented.

    “Readily recognizable letter shapes confirm that pen tip velocity is robustly encoded.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    Spatial dimensionality was only 1.24 times larger for characters (95% CI 1.19-1.30), but temporal dimensionality was 2.65 times larger (95% CI 2.58-2.72).

    “We found that spatial dimensionality was only modestly larger for characters (1.24 times larger; 95% CI = [1.19, 1.30]), but that the temporal dimensionality was much greater (2.65 times larger; 95% CI = [2.58, 2.72])”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    Offline autocorrection by a language model reduced the average character error rate to 0.89% and the average word error rate to 3.4% across all days.

    “The character error rate fell to 0.89% and the word error rate fell to 3.4% averaged across all days”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    A t-SNE visualization showed tight clusters of neural activity for individual characters and a mainly motoric organization in which characters written similarly were closer together.

    “The t-SNE visualization revealed tight clusters of neural activity for each character and a predominantly motoric encoding where characters that are written similarly are closer together.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    Participant T5 had a C4 AIS C spinal cord injury, was paralyzed below the neck, and had no functional hand movement beyond twitching and micromotion.

    “T5 has a high-level spinal cord injury (C4 AIS C) and was paralyzed from the neck down; his hand movements were entirely non-functional and limited to twitching and micromotion.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    In a toy model, letting trajectories vary over time increased the nearest-neighbor distance between neural trajectories and improved classification accuracy when noise was high enough.

    “Simply by allowing the trajectories to change in time (Fig. 4g), the nearest neighbor distance between the neural trajectories can be increased, resulting in an increase in classification accuracy when noise levels are large enough (Fig. 4h).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    When T5 freely answered open-ended questions, real-time performance was 73.8 characters per minute with an 8.54% character error rate, and 2.25% with a language model.

    “The results confirm that high performance can also be achieved when the user writes self-generated sentences as opposed to copying on-screen prompts (73.8 characters per minute with an 8.54% character error rate in real-time, 2.25% with a language model).”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    In a retrospective analysis, 10 calibration sentences (8.7 minutes) sufficed for an 8.5% raw error rate (1.7% with a language model), while 30 sentences were required to match the 5.9% raw online error rate.

    “We found that 10 sentences (8.7 minutes) were enough to achieve a raw error rate of 8.5% (1.7% with a language model), although 30 sentences were needed to match the raw online error rate of 5.9%.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationreasoning

    This temporal variety is probably one important factor, though not necessarily the only one, that made the handwriting BCI faster than continuous-motion point-and-click BCIs.

    “We think this is one, but not necessarily the only, important factor that enabled a handwriting BCI to go faster than continuous-motion point-and-click BCIs.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Interpretationreasoning

    Daily decoder retraining is intended to compensate for changes in neural recordings over time, which may arise from neural plasticity or electrode array micromotion.

    “Retraining helps account for changes in neural recordings that accrue over time, which might be caused by neural plasticity or electrode array micromotion.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    Other discrete classification-based BCIs have generally used directional movements with little temporal variety, which may have constrained their accuracy or the number of movements they can distinguish.

    “Other discrete (classification-based) BCIs have also typically used directional movements with little temporal variety, which may have limited their accuracy and/or the size of the movement set24,25.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [24] Musallam, S., Corneil, B. D., Greger, B., Scherberger, H. & Andersen, R. A. Cognitive control signals for neural prosthetics. Science 305, 258–262 (2004). source
    • cites [25] Santhanam, G., Ryu, S. I., Yu, B. M., Afshar, A. & Shenoy, K. V. A high-performance brain–computer interface. Nature 442, 195–198 (2006). source
  • May combine two claims.

    Interpretationown data

    The real-time system is general, self-paced, leaves the eyes free, and is accurate enough for real-world use: 94.1% raw accuracy and over 99% offline with a large-vocabulary language model.

    “The demonstrated real-time system is general (the user can express any sentence), easy to use (entirely self-paced and the eyes are free to move), and accurate enough to be useful in the real-world (94.1% raw accuracy, and >99% accuracy offline with a large-vocabulary language model).”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Interpretationreasoning

    These methods could be applied to other sequential behaviors that cannot be observed directly, such as decoding speech in someone who cannot speak.

    “These methods could be applied more generally to any sequential behavior that cannot be observed directly (e.g., decoding speech from someone who can no longer speak).”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Intracortical microelectrode array technology is still maturing and needs further evidence of longevity, safety, and efficacy before broad clinical adoption.

    “More broadly, intracortical microelectrode array technology is still maturing, and requires further demonstrations of longevity, safety, and efficacy before widespread clinical adoption35,36.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [35] Nurmikko, A. Challenges for large-scale cortical interfaces. Neuron 108, 259–269 (2020). source
    • cites [36] Vázquez-Guardado, A., Yang, Y., Bandodkar, A. J. & Rogers, J. A. Recent advances in neurotechnologies with broad potential for neuroscience research. Nat. Neurosci. 23, 1522–1536 (2020). source
  • May combine two claims.

    Interpretationreasoning

    The system is a single-participant proof of concept that a high-performance handwriting BCI is possible, not yet a complete clinically viable system.

    “Finally, it is important to recognize that the current system is a proof-of-concept that a high-performance handwriting BCI is possible (in a single participant); it is not yet a complete, clinically viable system.”
    Quote in the paperSubstantial claim
26 of 26
  • The authors state this as an assumption.

    It was not yet known whether the neural representation for a rapid, highly dexterous skill such as handwriting remains intact after paralysis.

    “However, it is still unknown whether the neural representation for a rapid and highly-dexterous motor skill, such as handwriting, also remains intact.”
1 of 1

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • The decoding speed is 3.4 times as fast as the previous record for any type of BCI.

    “which is 3.4 times as fast as the previous record8”

    From A high-performance speech neuroprosthesis (2023) · cites this paper as [8]

    The Discussion (page unavailable) reports 90 characters per minute for this BCI and 60 characters per minute for an earlier EEG speller. That makes the reported speed 1.5 times the earlier rate, not 3.4 times the previous record for any type of BCI. (LLM, conf=0.88)

    Checked by a reasoning model — may be wrong.

    Experimental — accuracy not yet measured
  • During 14 days of data collection shortly after implantation, text decoding performance exceeded previous BCIs' communication speeds by a factor of 4 or more.

    “During 14 days of data collection shortly after device implantation, we achieved high-performance text decoding, exceeding communication speeds of previous BCIs by a factor of 4 or more1,3,9”

    From A high-performance neuroprosthesis for speech decoding and avatar control (2023) · cites this paper as [9]

    The Discussion reports high-performance text decoding at 90 characters per minute, exceeding previously reported BCI speeds. But it also reports prior speeds of 40 characters per minute for intracortical point-and-click typing and 60 for a visually evoked EEG speller, so it does not support a fourfold advantage over previous BCIs generally. The Daily decoder retraining section says the copy-typing data spanned 28 days, while the Discussion refers to functionality more than 1,000 days after implantation, not data collection shortly after implantation. (LLM, conf=0.89)

    Experimental — accuracy not yet measured
  • A text-decoding-specific approach uses large language models to automatically recalibrate MEA-based text neuroprostheses.

    “A second approach, specific to text decoding, involves leveraging large language models to automatically recalibrate MEA-based text neuroprostheses.”

    From The speech neuroprosthesis (2024) · cites this paper as [9]

    The Daily decoder retraining section reports an offline test in which a language model corrected errors and enabled automatic, unsupervised recalibration of a handwriting decoder. It does not identify that model as a large language model, and it says the approach still needs online confirmation. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • A spelling framework using attempted speech or handwriting can facilitate a similar tradeoff, allowing users to spell arbitrary sentences with high accuracy but lower speeds.

    “A similar tradeoff can be facilitated by having a spelling framework available on the neuroprosthesis, either using attempted speech120 or handwriting9, which would allow users to spell out arbitrary sentences with high accuracy (albeit with substantially lower speeds).”

    From The speech neuroprosthesis (2024) · cites this paper as [9]

    The Discussion (page unavailable) says the handwriting BCI lets its user express any sentence, and Decoding handwritten sentences reports high accuracy. The paper does not establish the claimed tradeoff of substantially lower speed; it describes 90 characters per minute as a new BCI speed benchmark. The attempted-speech alternative has a separate citation and is not assessed here. (LLM, conf=0.83)

    Experimental — accuracy not yet measured
  • The median real-time text-decoding rate exceeded the participant's typical assistive-device communication rate of 14.2 words per minute and was closer to naturalistic speaking rates than previously reported communication neuroprostheses.

    “This decoding rate exceeds our participant’s typical communication rate using her assistive device (14.2 WPM; Supplementary Note 2) and is closer to naturalistic speaking rates than has been previously reported with communication neuroprostheses1,3,7–9.”

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Authors
Willett, F. R., Avansino, D. T., Hochberg, L. R., Henderson, J. M., & Shenoy, K. V.
Affiliations
  • Howard Hughes Medical Institute (US)
  • Harvard University (US)
  • Stanford Medicine (US)
Corresponding author
Willett, Francis R.
Venue
Nature
Published
2021-05-12
Volume
593
Issue
7858
Pages
249-254
ISSN
  • 0028-0836 (ISSN-L)
  • 1476-4687
OpenAlex
W3161343553
Cited by
969
References
50
Citations by year
2026: 143 · 2025: 214 · 2024: 203 · 2023: 201 · 2022: 134 · 2021: 68 · 2020: 4 · 2019: 2
FWCI
72.98
Type
journal article
Language
en
Open access
Locations
  • Nature (publishedVersion)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion, public-domain)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (submittedVersion)
  • PubMed Central (submittedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
Funders
  • Howard Hughes Medical Institute
  • U.S. Department of Veterans Affairs (I01 RX002295, I50RX002864, B6453-R, N-2864-C)
  • Office of Research and Development (N2864C, B6453R)
  • National Institutes of Health (U01NS098968, R01DC014034)
  • National Institute on Deafness and Other Communication Disorders (R01DC009899, R01-DC014034, DC017844, DC014034, U01- DC017844)
  • National Institute of Neurological Disorders and Stroke (U01NS098968, UH2-NS095548, UO1-NS098968, NS098968, NS095548)
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › EEG and Brain-Computer Interfaces
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Neuroscience and Neural Engineering
  • Physical Sciences › Computer Science › Human-Computer Interaction › Gaze Tracking and Assistive Technology
Keywords
brain-computer interface, handwriting, text entry, motor cortex, intracortical recording, spinal cord injury, paralysis, real-time communication, typing speed
MeSH terms
Brain, Communication, Handwriting, Humans, Spinal Cord Injuries, Time Factors, Neural Networks, Computer, Brain-Computer Interfaces

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-09-28.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-09-28.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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