[ { "id": "authors:hxt1q-16v95", "collection": "authors", "collection_id": "hxt1q-16v95", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230227-322609000.1", "type": "monograph", "title": "Online internal speech decoding from single neurons in a human participant", "author": [ { "family_name": "Wandelt", "given_name": "Sarah K.", "orcid": "0000-0001-9551-8491", "clpid": "Wandelt-Sarah-K" }, { "family_name": "Bj\u00e5nes", "given_name": "David A.", "orcid": "0000-0002-1208-5916", "clpid": "Bj\u00e5nes-David-A" }, { "family_name": "Pejsa", "given_name": "Kelsie", "clpid": "Pejsa-Kelsie-W" }, { "family_name": "Lee", "given_name": "Brian", "orcid": "0000-0002-3592-8146", "clpid": "Lee-Brian" }, { "family_name": "Liu", "given_name": "Charles", "orcid": "0000-0001-6423-8577", "clpid": "Liu-Charles-Y" }, { "family_name": "Andersen", "given_name": "Richard A.", "orcid": "0000-0002-7947-0472", "clpid": "Andersen-R-A" } ], "abstract": "Speech brain-machine interfaces (BMI's) translate brain signals into words or audio outputs, enabling communication for people having lost their speech abilities due to diseases or injury. While important advances in vocalized, attempted, and mimed speech decoding have been achieved, results for internal speech decoding are sparse, and have yet to achieve high functionality. Notably, it is still unclear from which brain areas internal speech can be decoded. In this work, a tetraplegic participant with implanted microelectrode arrays located in the supramarginal gyrus (SMG) and primary somatosensory cortex (S1) performed internal and vocalized speech of six words and two pseudowords. We found robust internal speech decoding from SMG single neuron activity, achieving up to 91% classification accuracy during an online task (chance level 12.5%). Evidence of shared neural representations between internal speech, word reading, and vocalized speech processes were found. SMG represented words in different languages (English/ Spanish) as well as pseudowords, providing evidence for phonetic encoding. Furthermore, our decoder achieved high classification with multiple internal speech strategies (auditory imagination/ visual imagination). Activity in S1 was modulated by vocalized but not internal speech, suggesting no articulator movements of the vocal tract occurred during internal speech production. This works represents the first proof-of-concept for a high-performance internal speech BMI.", "doi": "10.1101/2022.11.02.22281775", "publication_date": "2022-11-06" }, { "id": "authors:ppn2k-4mn41", "collection": "authors", "collection_id": "ppn2k-4mn41", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230322-368377000.37", "type": "monograph", "title": "S1 represents multisensory contexts and somatotopic locations within and outside the bounds of the cortical homunculus", "author": [ { "family_name": "Rosenthal", "given_name": "Isabelle A.", "orcid": "0000-0002-9791-3820", "clpid": "Rosenthal-Isabelle-A" }, { "family_name": "Bashford", "given_name": "Luke", "orcid": "0000-0003-4391-2491", "clpid": "Bashford-Luke" }, { "family_name": "Kellis", "given_name": "Spencer", "orcid": "0000-0002-5158-1058", "clpid": "Kellis-Spencer-S" }, { "family_name": "Pejsa", "given_name": "Kelsie", "clpid": "Pejsa-Kelsie-W" }, { "family_name": "Lee", "given_name": "Brian", "orcid": "0000-0002-3592-8146", "clpid": "Lee-Brian" }, { "family_name": "Liu", "given_name": "Charles", "orcid": "0000-0001-6423-8577", "clpid": "Liu-Charles-Y" }, { "family_name": "Andersen", "given_name": "Richard A.", "orcid": "0000-0002-7947-0472", "clpid": "Andersen-R-A" } ], "abstract": "The responsiveness of primary somatosensory cortex (S1) to physical tactile stimuli is well documented but the extent to which it is modulated by vision is unresolved. Additionally, recent literature has suggested that tactile events are represented in S1 in a more complex, generalized manner than its long-established topographic organization. To better characterize S1 function, neural activity was recorded from a tetraplegic patient implanted with microelectrode arrays in S1 during 1s stroking touches to the forearm (evoking numb sensation) or finger (naturalistic sensation). Touch conditions included visually observed first person physical touches, physical touches without vision, and visual touches without physical contact which occurred either to a third person, an inanimate object, or the patient's own body in virtual reality. Two major findings emerged from this dataset. The first was that vision strongly modulates S1 activity, but only if there is a physical element to the touch, suggesting that passive observation of touches is not sufficient to recruit S1 neurons. The second was that despite the location of the recording arrays in a putative arm area of S1, neural activity was able to represent both arm and finger touches in physical touch conditions. Arm touches were encoded more strongly and specifically, supporting the idea that S1 encodes tactile events primarily through its topographic organization, as well as in a more general manner encompassing larger areas of the body.", "doi": "10.1101/2022.08.29.505313", "publication_date": "2022-08-31" }, { "id": "authors:02vq1-gw339", "collection": "authors", "collection_id": "02vq1-gw339", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230323-759050000.1", "type": "monograph", "title": "Multi-channel intra-cortical micro-stimulation yields quick reaction times and evokes natural somatosensations in a human participant", "author": [ { "family_name": "Bj\u00e5nes", "given_name": "David A.", "orcid": "0000-0002-1208-5916", "clpid": "Bj\u00e5nes-David-A" }, { "family_name": "Bashford", "given_name": "Luke", "orcid": "0000-0003-4391-2491", "clpid": "Bashford-Luke" }, { "family_name": "Pejsa", "given_name": "Kelsie", "clpid": "Pejsa-Kelsie-W" }, { "family_name": "Lee", "given_name": "Brian", "orcid": "0000-0002-3592-8146", "clpid": "Lee-Brian" }, { "family_name": "Liu", "given_name": "Charles Y.", "orcid": "0000-0001-6423-8577", "clpid": "Liu-Charles-Y" }, { "family_name": "Andersen", "given_name": "Richard A.", "orcid": "0000-0002-7947-0472", "clpid": "Andersen-R-A" } ], "abstract": "Somatosensory brain-machine-interfaces (BMIs) can create naturalistic sensations by modulating activity of neural populations in the brain. By utilizing different spatial or temporal patterns of intra-cortical micro-stimulation (ICMS) in primary sensory cortex (S1), human patients suffering somatosensory loss can experience both cutaneous and proprioceptive sensory feedback. As evidenced by motor deficits in deafferented patients, rapid somatosensory feedback is critical for dexterous motor ability, in part because visual feedback is much slower than naturally occurring somatosensory input. However, somatosensory BMI studies typically report significantly longer cognitive processing latencies for cortical electrical stimulation than for naturally occurring somatosensations or visual sensations. \n\nIn this study, we show that multi-channel electrical stimulation patterns elicit naturalistic somatosensory percepts in a human tetraplegic participant. Crucially, somatosensations evoked by multi-channel ICMS are cognitively processed at comparable latencies to naturally evoked sensations and significantly faster than visual sensations, as measured via a simple reaction time test. Further investigation demonstrated multi-channel stimulation could significantly reduce minimum amplitude detection thresholds and such reductions in charge density resulted in more frequent \"natural\" sensation descriptors reported by the human participant. Multi-channel ICMS patterns also evoked percepts with highly stable somatotopic locations. While some single-channel ICMS patterns evoked sensations 20-80% of the time, most multi-channel patterns could evoke sensations with 100% repeatability, an important step in demonstrating BCI device reliability. These improvements are all significant advances towards state-of-the-art sensory BMIs. The addition of such low-latency artificial sensory feedback to motor BMIs is expected to improve movement accuracy and increase embodiment for human users.", "doi": "10.1101/2022.08.08.22278389", "publication_date": "2022-08-10" } ]