# Casey Harrell **Entity class:** Person **Domain:** Brain-Computer Interface Participants / Speech Restoration **Doc Type:** Person Node **Maturity:** Developed **Collection:** [[collections/Neurotech|Neurotech]] **Primary Sources:** *Nature Medicine*, June 2026; *New England Journal of Medicine*, 2024 ## Definition **Casey Harrell is the man with amyotrophic lateral sclerosis whose years of daily brain-computer-interface use produced the longest record of independent speech restoration in the corpus.** He is a participant in the [[wiki/BrainGate|BrainGate2]] clinical trial, identified in the publications as [[wiki/T15|T15]] and named in UC Davis reporting. In July 2023 the neurosurgeon [[wiki/David Brandman|David Brandman]] implanted four microelectrode arrays, 256 cortical electrodes in total, in his left precentral gyrus. ## Record | Item | Record | |---|---| | Implant | July 2023, four arrays in the left precentral gyrus, 256 electrodes | | Surgeon and site | [[wiki/David Brandman\|David Brandman]], UC Davis Health | | First publication | Speech decoding, *New England Journal of Medicine*, 2024 | | Home use | More than 3,800 hours of independent operation with no researchers present, over about nineteen months | | Output | 183,060 sentences totaling 1,960,163 words, averaging 56 words per minute | | Accuracy | 92% of sentences rated by him as accurate or mostly correct; 99.2% word accuracy in structured testing against a 125,000-word vocabulary | | Second publication | Independent daily use, *Nature Medicine*, June 2026 | Care-partner assistance was largely limited to putting the hardware on and starting the software. He sustained full-time employment while using the system. ## Reading Locked-in patients are the population for whom the interface is the only channel, which makes them the group that uses the highest-bandwidth configurations first and longest. Clinical necessity, not enthusiasm, produced the first humans who have lived years mediated by a decoder, and Harrell's record is the corpus's primary evidence that the arrangement holds up in ordinary life rather than in a laboratory session. His restored voice is synthesized from a model of his own pre-morbid speech, which makes the resulting identity object part biological and part trained artifact. ## Research Inferences These entries translate the forward-looking register in [[research/Research Inferences|Research Inferences]] into ordinary wiki prose. The tier labels apply to the inference, not automatically to every factual anchor inside it. Proposed IDs above INF-0500 come from the 2026-10-23 cycle: [[research/Research Inferences Integration Report - 2026-10-23|Research Inferences Integration Report — 2026-10-23]] · [[research/Research Inferences Integration Audit - 2026-10-23|Research Inferences Integration Audit — 2026-10-23]]. - **INF-0022 — Strongly indicated.** Locked-in patients are the population for whom the interface is the only channel, which makes them the group that will use the highest-bandwidth configurations first and longest. Clinical necessity, not enthusiasm, will produce the first humans who have lived years mediated by a decoder. - **INF-0007 — Strongly indicated.** Academic speech BCIs reached 62–78 words per minute with implanted electrodes and model-side decoding, which means the recent gains are attributable to the decoder more than the sensor. Decoder improvement is free of surgical risk and compounds across every existing implant already in a head. - **INF-0096 — Strongly indicated.** Restoring speech with a synthesized version of the person's own pre-morbid voice is already technically routine. The restored person therefore speaks in a voice generated from a model, and the resulting identity object is part biological, part trained artifact. - **INF-0020 — Established.** Decoders drift as the recording population changes, so every chronic BCI is already running a continuous identity-maintenance process on a moving substrate. That maintenance loop is a working prototype of the problem any uploaded state would face, running today in clinic. - **INF-0099 — Plausible.** Once cognitive function is routinely mediated, removing the mediator produces measurable deficit, which gives the interface the standing of a prosthesis for capacities that were never lost. Dependency is not a side effect of this architecture; it is the operating condition it creates. ## Relationships - **participant_in:** [[wiki/BrainGate|BrainGate]] (BrainGate2 trial) · [[wiki/BrainGate2 home BCI|BrainGate2 home BCI]] · [[wiki/BrainGate2 long-term home BCI study|BrainGate2 long-term home BCI study]]. - **participant_identifier:** [[wiki/T15|T15]]. - **implanting_surgeon:** [[wiki/David Brandman|David Brandman]]. - **condition:** [[wiki/Amyotrophic Lateral Sclerosis|Amyotrophic Lateral Sclerosis]] · [[wiki/Locked-In Syndrome|Locked-In Syndrome]]. - **capability_class:** [[wiki/Speech Neuroprosthesis|Speech Neuroprosthesis]] · [[wiki/Speech Restoration|Speech Restoration]]. - **peer_participants:** Kenneth Shock and the participant known as Terry in the [[wiki/Neuralink VOICE Trial|Neuralink VOICE Trial]]; the first [[wiki/Connect-One|Connect-One]] participant with [[wiki/Paradromics Connexus|Paradromics Connexus]]. - **cluster_home:** [[wiki/Neural Interfaces and Continuity Architecture|Neural Interfaces and Continuity Architecture]]. - **ecosystem:** [[collections/Neurotech|Neurotech]]. ## Sources - [Brain-computer interface enables independent, accurate communication for man living with ALS — UC Davis Health, June 2026](https://health.ucdavis.edu/pmr/news/headlines/brain-computer-interface-enables-independent-accurate-communication-for-man-living-with-als/2026/06) - [New brain-computer interface allows man with ALS to speak again — UC Davis Health, August 2024](https://health.ucdavis.edu/research/news/headlines/new-brain-computer-interface-allows-man-with-als-to-speak-again/2024/08) - [articles/Technologies for Consciousness Mapping and Transfer](articles/Technologies%20for%20Consciousness%20Mapping%20and%20Transfer.md) — section I, for the home-use figures. As of 23 October 2026.