Inner speech in motor cortex and implications for speech neuroprostheses
Speech brain-computer interfaces (BCIs) show promise in restoring communication to people with paralysis but have also prompted discussions regarding their potential to decode private inner speech. Separately, inner speech may be a way to bypass the current approach of requiring speech BCI users to physically attempt speech, which is fatiguing and can slow communication. Using multi-unit recordings from four participants, we found that inner speech is robustly represented in the motor cortex and that imagined sentences can be decoded in real time. The representation of inner speech was highly correlated with attempted speech, though we also identified a neural "motor-intent" dimension that differentiates the two. We investigated the possibility of decoding private inner speech and found that some aspects of free-form inner speech could be decoded during sequence recall and counting tasks. Finally, we demonstrate high-fidelity strategies that prevent speech BCIs from unintentionally decoding private inner speech.
Authors
- Samuel R. Nason (ORCID: https://orcid.org/0000-0002-7127-0986)
- Jaimie M. Henderson (ORCID: https://orcid.org/0000-0002-3276-2267)
- Carrina Iacobacci (ORCID: https://orcid.org/0000-0003-1690-6272)
- Brandon G. Jacques
- Donald T. Avansino (ORCID: https://orcid.org/0000-0002-7974-0153)
- Leigh R. Hochberg (ORCID: https://orcid.org/0000-0003-0261-2273)
- Shaul Druckmann
- David M. Brandman (ORCID: https://orcid.org/0000-0003-3224-7019)
- Daniel B. Rubin (ORCID: https://orcid.org/0000-0001-6982-9587)
- Foram Kamdar (ORCID: https://orcid.org/0009-0000-2734-3247)
- Akansha Singh (ORCID: https://orcid.org/0000-0001-9101-4157)
- Sergey D. Stavisky (ORCID: https://orcid.org/0000-0002-5238-0573)
- Chethan Pandarinath (ORCID: https://orcid.org/0000-0003-1241-1432)
- Francis R. Willett (ORCID: https://orcid.org/0000-0002-2652-8511)
- Justin Jude (ORCID: https://orcid.org/0000-0002-0175-1856)
- Ziv M. Williams (ORCID: https://orcid.org/0000-0002-0017-0048)
- Erin M. Kunz (ORCID: https://orcid.org/0009-0003-5246-6937)
- Nicholas S. Card (ORCID: https://orcid.org/0000-0002-6858-268X)
- Nick Hahn
- Payton Bechefsky
- Soo Jin Yoon (ORCID: https://orcid.org/0000-0002-4103-1546)
- Nicholas Au Yong
- Benyamin Abramovich Krasa
Institutions
- Georgia Institute of Technology (US)
- Howard Hughes Medical Institute (US)
- Harvard University (US)
- Emory University (US)
- Neurosciences Institute (US)
- The Wallace H. Coulter Department of Biomedical Engineering (US)
- Providence VA Medical Center (US)
- Massachusetts General Hospital (US)
- Center for Neuro-Oncology (US)
- Neurological Surgery (US)
- University of California, Davis (US)
- Stanford University (US)
Publication Details
- Journal
- Cell
- Published
- 2025-08-01
- DOI
- https://doi.org/10.1016/j.cell.2025.06.015
- Citations
- 17
- Primary Topic
- EEG and Brain-Computer Interfaces
- Type
- article
- Field-Weighted Citation Impact
- 24.33
Funders
- Howard Hughes Medical Institute
- Simons Foundation
- A.P. Giannini Foundation
- National Institute on Deafness and Other Communication Disorders
- National Institute of Neurological Disorders and Stroke
- Eunice Kennedy Shriver National Institute of Child Health and Human Development