Objective. Neural prosthetics represent a significant opportunity for control of external effectors like artificial limbs and computer devices as well as a means for interacting with virtual reality. Prior studies have shown posterior parietal cortex (PPC) to be a viable source of signals for the purposes of decoding motor intentions given its representation of both visual inputs and motor outputs. Additionally, signals in parietal cortex have been shown to be associated with tool use the body schema. We investigated if more realistic movement effectors in virtual reality might elicit stronger signals at the single neuron level in parietal cortex.
\nApproach. A quadriplegic human subject was implanted with multi-electrode recording arrays in the PPC. Neural spiking and local field potentials were recorded during attempted movement in a computer-rendered, stereoscopic, 3D virtual environment. Tuning to different movement effectors was examined using a first-person movement generation task in addition to closed loop control performance.
\nMain results. We found single neurons and simultaneously recorded field potentials in a quadriplegic patient exhibited enhanced responses during attempted (rather than passively observed) movement of a realistic and ‘attached’ 3D arm relative to either a visually similar but ‘detached’ 2D arm or a non-anthropomorphic abstract effector. These preferences were found despite the patient having lost motor function years prior. These differences did not effect performance during closed loop brain control of the movement effectors.
\nSignificance. In human parietal cortex, single neuron activity and local field potentials responded preferentially to visually guided attempted movement of a realistic arm rather than abstract effector. However, this tuning did not affect closed loop brain control in a virtual reality environment when preceded by a text-based decoder training paradigm.
", "doi": "10.1088/1741-2552/adc3ca", "issn": "1741-2560", "publisher": "IOP Publishing", "publication": "Journal of Neural Engineering", "publication_date": "2025-04", "series_number": "2", "volume": "22", "issue": "2", "pages": "026037" }, { "id": "authors:qy2y0-pb111", "collection": "authors", "collection_id": "qy2y0-pb111", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230615-812805000.12", "type": "article", "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": "Recent literature suggests that tactile events are represented in the primary somatosensory cortex (S1) beyond its long-established topography; in addition, the extent to which S1 is modulated by vision remains unclear. To better characterize S1, human electrophysiological data were recorded during touches to the forearm or finger. Conditions included visually observed physical touches, physical touches without vision, and visual touches without physical contact. Two major findings emerge from this dataset. First, vision strongly modulates S1 area 1, but only if there is a physical element to the touch, suggesting that passive touch observation is insufficient to elicit neural responses. Second, despite recording in a putative arm area of S1, neural activity represents both arm and finger stimuli during physical touches. Arm touches are encoded more strongly and specifically, supporting the idea that S1 encodes tactile events primarily through its topographic organization but also more generally, encompassing other areas of the body.", "doi": "10.1016/j.celrep.2023.112312", "pmcid": "PMC10544688", "issn": "2211-1247", "publisher": "Cell Press", "publication": "Cell Reports", "publication_date": "2023-04-25", "series_number": "4", "volume": "42", "issue": "4", "pages": "112312" }, { "id": "authors:2g6g3-vqe14", "collection": "authors", "collection_id": "2g6g3-vqe14", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211103-170317858", "type": "article", "title": "Decoding grasp and speech signals from the cortical grasp circuit in a tetraplegic human", "author": [ { "family_name": "Wandelt", "given_name": "Sarah K.", "orcid": "0000-0001-9551-8491", "clpid": "Wandelt-Sarah-K" }, { "family_name": "Kellis", "given_name": "Spencer", "orcid": "0000-0002-5158-1058", "clpid": "Kellis-Spencer-S" }, { "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": "The cortical grasp network encodes planning and execution of grasps and processes spoken and written aspects of language. High-level cortical areas within this network are attractive implant sites for brain-machine interfaces (BMIs). While a tetraplegic patient performed grasp motor imagery and vocalized speech, neural activity was recorded from the supramarginal gyrus (SMG), ventral premotor cortex (PMv), and somatosensory cortex (S1). In SMG and PMv, five imagined grasps were well represented by firing rates of neuronal populations during visual cue presentation. During motor imagery, these grasps were significantly decodable from all brain areas. During speech production, SMG encoded both spoken grasp types and the names of five colors. Whereas PMv neurons significantly modulated their activity during grasping, SMG's neural population broadly encoded features of both motor imagery and speech. Together, these results indicate that brain signals from high-level areas of the human cortex could be used for grasping and speech BMI applications.", "doi": "10.1016/j.neuron.2022.03.009", "pmcid": "PMC9186423", "issn": "0896-6273", "publisher": "Cell Press", "publication": "Neuron", "publication_date": "2022-06-01", "series_number": "11", "volume": "110", "issue": "11", "pages": "1777-1787" }, { "id": "authors:syt7v-h7h38", "collection": "authors", "collection_id": "syt7v-h7h38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210122-144955862", "type": "article", "title": "The Neurophysiological Representation of Imagined Somatosensory Percepts in Human Cortex", "author": [ { "family_name": "Bashford", "given_name": "Luke", "orcid": "0000-0003-4391-2491", "clpid": "Bashford-Luke" }, { "family_name": "Rosenthal", "given_name": "Isabelle", "orcid": "0000-0002-9791-3820", "clpid": "Rosenthal-Isabelle-A" }, { "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": "Kramer", "given_name": "Daniel", "orcid": "0000-0003-4551-2977", "clpid": "Kramer-Daniel-Richard" }, { "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": "Intracortical microstimulation (ICMS) in human primary somatosensory cortex (S1) has been used to successfully evoke naturalistic sensations. However, the neurophysiological mechanisms underlying the evoked sensations remain unknown. To understand how specific stimulation parameters elicit certain sensations we must first understand the representation of those sensations in the brain. In this study we record from intracortical microelectrode arrays implanted in S1, premotor cortex, and posterior parietal cortex of a male human participant performing a somatosensory imagery task. The sensations imagined were those previously elicited by ICMS of S1, in the same array of the same participant. In both spike and local field potential recordings, features of the neural signal can be used to classify different imagined sensations. These features are shown to be stable over time. The sensorimotor cortices only encode the imagined sensation during the imagery task, while posterior parietal cortex encodes the sensations starting with cue presentation. These findings demonstrate that different aspects of the sensory experience can be individually decoded from intracortically recorded human neural signals across the cortical sensory network. Activity underlying these unique sensory representations may inform the stimulation parameters for precisely eliciting specific sensations via ICMS in future work.", "doi": "10.1523/jneurosci.2460-20.2021", "pmcid": "PMC8018772", "issn": "0270-6474", "publisher": "Society for Neuroscience", "publication": "Journal of Neuroscience", "publication_date": "2021-03-10", "series_number": "10", "volume": "41", "issue": "10", "pages": "2177-2185" }, { "id": "authors:f04yf-40y52", "collection": "authors", "collection_id": "f04yf-40y52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200730-111737023", "type": "article", "title": "Neural encoding of actual and imagined touch within human posterior parietal cortex", "author": [ { "family_name": "Chivukula", "given_name": "Srinivas", "orcid": "0000-0002-3570-162X", "clpid": "Chivukula-Srinivas" }, { "family_name": "Zhang", "given_name": "Carey Y.", "orcid": "0000-0001-9867-4510", "clpid": "Zhang-Carey-Y" }, { "family_name": "Aflalo", "given_name": "Tyson", "orcid": "0000-0002-0101-2455", "clpid": "Aflalo-Tyson" }, { "family_name": "Jafari", "given_name": "Matiar", "orcid": "0000-0002-2224-4896", "clpid": "Jafari-Matiar" }, { "family_name": "Pejsa", "given_name": "Kelsie", "clpid": "Pejsa-Kelsie-W" }, { "family_name": "Pouratian", "given_name": "Nader", "orcid": "0000-0002-0426-3241", "clpid": "Pouratian-Nader" }, { "family_name": "Andersen", "given_name": "Richard A.", "orcid": "0000-0002-7947-0472", "clpid": "Andersen-R-A" } ], "abstract": "In the human posterior parietal cortex (PPC), single units encode high-dimensional information with partially mixed representations that enable small populations of neurons to encode many variables relevant to movement planning, execution, cognition, and perception. Here, we test whether a PPC neuronal population previously demonstrated to encode visual and motor information is similarly engaged in the somatosensory domain. We recorded neurons within the PPC of a human clinical trial participant during actual touch presentation and during a tactile imagery task. Neurons encoded actual touch at short latency with bilateral receptive fields, organized by body part, and covered all tested regions. The tactile imagery task evoked body part-specific responses that shared a neural substrate with actual touch. Our results are the first neuron-level evidence of touch encoding in human PPC and its cognitive engagement during a tactile imagery task, which may reflect semantic processing, attention, sensory anticipation, or imagined touch.", "doi": "10.7554/eLife.61646", "pmcid": "PMC7924956", "issn": "2050-084X", "publisher": "eLife Sciences Publications", "publication": "eLife", "publication_date": "2021-03-01", "volume": "10", "pages": "Art. No. e61646" }, { "id": "authors:s36my-hk448", "collection": "authors", "collection_id": "s36my-hk448", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190307-092211759", "type": "article", "title": "Intrinsic Variable Learning for Brain-Machine Interface Control by Human Anterior Intraparietal Cortex", "author": [ { "family_name": "Sakellaridi", "given_name": "Sofia", "clpid": "Sakellaridi-Sofia" }, { "family_name": "Christopoulos", "given_name": "Vassilios N.", "clpid": "Christopoulos-Vassilios-N" }, { "family_name": "Aflalo", "given_name": "Tyson", "clpid": "Aflalo-Tyson" }, { "family_name": "Pejsa", "given_name": "Kelsie W.", "clpid": "Pejsa-Kelsie-W" }, { "family_name": "Rosario", "given_name": "Emily R.", "clpid": "Rosario-Emily-R" }, { "family_name": "Ouellette", "given_name": "Debra", "clpid": "Ouellette-Debra" }, { "family_name": "Pouratian", "given_name": "Nader", "clpid": "Pouratian-Nader" }, { "family_name": "Andersen", "given_name": "Richard A.", "orcid": "0000-0002-7947-0472", "clpid": "Andersen-R-A" } ], "abstract": "Although animal studies provided significant insights in understanding the neural basis of learning and adaptation, they often cannot dissociate between different learning mechanisms due to the lack of verbal communication. To overcome this limitation, we examined the mechanisms of learning and its limits in a human intracortical brain-machine interface (BMI) paradigm. A tetraplegic participant controlled a 2D computer cursor by modulating single-neuron activity in the anterior intraparietal area (AIP). By perturbing the neuron-to-movement mapping, the participant learned to modulate the activity of the recorded neurons to solve the perturbations by adopting a target re-aiming strategy. However, when no cognitive strategies were adequate to produce correct responses, AIP failed to adapt to perturbations. These findings suggest that learning is constrained by the pre-existing neuronal structure, although it is possible that AIP needs more training time to learn to generate novel activity patterns when cognitive re-adaptation fails to solve the perturbations.", "doi": "10.1016/j.neuron.2019.02.012", "pmcid": "PMC6922088", "issn": "0896-6273", "publisher": "Cell Press", "publication": "Neuron", "publication_date": "2019-05-08", "series_number": "3", "volume": "102", "issue": "3", "pages": "694-705" }, { "id": "authors:vymrt-ceg43", "collection": "authors", "collection_id": "vymrt-ceg43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151120-091934442", "type": "article", "title": "Hand Shape Representations in the Human Posterior Parietal Cortex", "author": [ { "family_name": "Klaes", "given_name": "Christian", "orcid": "0000-0003-4767-9631", "clpid": "Klaes-Christian" }, { "family_name": "Kellis", "given_name": "Spencer", "orcid": "0000-0002-5158-1058", "clpid": "Kellis-Spencer-S" }, { "family_name": "Aflalo", "given_name": "Tyson", "orcid": "0000-0002-0101-2455", "clpid": "Aflalo-Tyson" }, { "family_name": "Lee", "given_name": "Brian", "orcid": "0000-0002-3592-8146", "clpid": "Lee-Brian" }, { "family_name": "Pejsa", "given_name": "Kelsie", "clpid": "Pejsa-Kelsie-W" }, { "family_name": "Shanfield", "given_name": "Kathleen", "clpid": "Shanfield-Kathleen" }, { "family_name": "Hayes-Jackson", "given_name": "Stephanie", "clpid": "Hayes-Jackson-Stephanie" }, { "family_name": "Aisen", "given_name": "Mindy", "clpid": "Aisen-Mindy" }, { "family_name": "Heck", "given_name": "Christi", "clpid": "Heck-Christianne--N" }, { "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": "Humans shape their hands to grasp, manipulate objects, and to communicate. From nonhuman primate studies, we know that visual and motor properties for grasps can be derived from cells in the posterior parietal cortex (PPC). Are non-grasp-related hand shapes in humans represented similarly? Here we show for the first time how single neurons in the PPC of humans are selective for particular imagined hand shapes independent of graspable objects. We find that motor imagery to shape the hand can be successfully decoded from the PPC by implementing a version of the popular Rock-Paper-Scissors game and its extension Rock-Paper-Scissors-Lizard-Spock. By simultaneous presentation of visual and auditory cues, we can discriminate motor imagery from visual information and show differences in auditory and visual information processing in the PPC. These results also demonstrate that neural signals from human PPC can be used to drive a dexterous cortical neuroprosthesis.", "doi": "10.1523/JNEUROSCI.2747-15.2015", "pmcid": "PMC4649012", "issn": "0270-6474", "publisher": "Society for Neuroscience", "publication": "Journal of Neuroscience", "publication_date": "2015-11-18", "series_number": "46", "volume": "35", "issue": "46", "pages": "15466-15476" }, { "id": "authors:ww312-r5r29", "collection": "authors", "collection_id": "ww312-r5r29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150217-102913989", "type": "article", "title": "Decoding Motor Imagery from the Posterior Parietal Cortex of a Tetraplegic Human", "author": [ { "family_name": "Aflalo", "given_name": "Tyson", "orcid": "0000-0002-0101-2455", "clpid": "Aflalo-Tyson" }, { "family_name": "Kellis", "given_name": "Spencer", "orcid": "0000-0002-5158-1058", "clpid": "Kellis-Spencer-S" }, { "family_name": "Klaes", "given_name": "Christian", "orcid": "0000-0003-4767-9631", "clpid": "Klaes-Christian" }, { "family_name": "Lee", "given_name": "Brian", "orcid": "0000-0002-3592-8146", "clpid": "Lee-Brian" }, { "family_name": "Shi", "given_name": "Ying", "clpid": "Shi-Ying" }, { "family_name": "Pejsa", "given_name": "Kelsie", "clpid": "Pejsa-Kelsie-W" }, { "family_name": "Shanfield", "given_name": "Kathleen", "clpid": "Shanfield-Kathleen" }, { "family_name": "Hayes-Jackson", "given_name": "Stephanie", "clpid": "Hayes-Jackson-Stephanie" }, { "family_name": "Aisen", "given_name": "Mindy", "clpid": "Aisen-Mindy" }, { "family_name": "Heck", "given_name": "Christi", "clpid": "Heck-Christianne--N" }, { "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": "Nonhuman primate and human studies have suggested that populations of neurons in the\nposterior parietal cortex (PPC) may represent high-level aspects of action planning that can\nbe used to control external devices as part of a brain-machine interface. However, there is no\ndirect neuron-recording evidence that human PPC is involved in action planning, and the\nsuitability of these signals for neuroprosthetic control has not been tested.We recorded\nneural population activity with arrays of microelectrodes implanted in the PPC of a tetraplegic\nsubject. Motor imagery could be decoded from these neural populations, including imagined\ngoals, trajectories, and types of movement.These findings indicate that the PPC of humans\nrepresents high-level, cognitive aspects of action and that the PPC can be a rich source for\ncognitive control signals for neural prosthetics that assist paralyzed patients.", "doi": "10.1126/science.aaa5417", "pmcid": "PMC4896830", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "2015-05-22", "series_number": "6237", "volume": "348", "issue": "6237", "pages": "906-910" } ]