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1.
J Neuroeng Rehabil ; 19(1): 118, 2022 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-36329467

RESUMO

BACKGROUND: To evaluate the relationship between measures of neuromuscular impairment and limb accelerations (LA) collected during sleep among individuals with chronic spinal cord injury (SCI) to provide evidence of construct and concurrent validity for LA as a clinically meaningful measure. METHODS: The strength (lower extremity motor score), sensation (summed lower limb light touch scores), and spasticity (categorized lower limb Modified Ashworth Scale) were measured from 40 adults with chronic (≥ 1 year) SCI. Demographics, pain, sleep quality, and other covariate or confounding factors were measured using self-report questionnaires. Each participant then wore ActiGraph GT9X Link accelerometers on their ankles and wrist continuously for 1-5 days to measure LA from movements during sleep. Regression models with built-in feature selection were used to determine the most relevant LA features and the association to each measure of impairment. RESULTS: LA features were related to measures of impairment with models explaining 69% and 73% of the variance (R²) in strength and sensation, respectively, and correctly classifying 81.6% (F1-score = 0.814) of the participants into spasticity categories. The most commonly selected LA features included measures of power and frequency (frequency domain), movement direction (correlation between axes), consistency between movements (relation to recent movements), and wavelet energy (signal characteristics). Rolling speed (change in angle of inclination) and movement smoothness (median crossings) were uniquely associated with strength. When LA features were included, an increase of 72% and 222% of the variance was explained for strength and sensation scores, respectively, and there was a 34% increase in spasticity classification accuracy compared to models containing only covariate features such as demographics, sleep quality, and pain. CONCLUSION: LA features have shown evidence of having construct and concurrent validity, thus demonstrating that LA are a clinically-relevant measure related to lower limb strength, sensation, and spasticity after SCI. LA may be useful as a more detailed measure of impairment for applications such as clinical prediction models for ambulation.


Assuntos
Espasticidade Muscular , Traumatismos da Medula Espinal , Adulto , Humanos , Espasticidade Muscular/etiologia , Espasticidade Muscular/complicações , Traumatismos da Medula Espinal/complicações , Sensação , Extremidade Superior , Aceleração , Sono , Dor
2.
J Physiol ; 599(18): 4357-4373, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34021605

RESUMO

KEY POINTS: Muscle weakness after stroke results from damage to corticospinal fibres that structurally and functionally connect cerebral cortex to the spinal cord. Here, we show an asymmetry in corticospinal recruitment of spinal motor neurons that is linked to maximal voluntary output of hand muscles weakened by stroke. Spike timing-dependent plasticity of synapses between corticospinal and spinal motor neurons transiently reversed recruitment failures in some survivors. These modulatory effects were strongly associated with recruitment asymmetry and hand impairment. Our findings highlight the functional relevance of spinal motor neuron recruitment by corticospinal inputs and the viability of corticospinal motor neuronal synapses for restoring activation of lower motor neurons after stroke. ABSTRACT: Corticospinal input to spinal motor neurons is structurally and functionally altered by hemiparetic stroke. The pattern and extent to which corticospinal recruitment of spinal motor neurons is reorganized and whether such changes are linked to the severity of motor impairments is not well understood. Here, we performed experiments using the triple stimulation technique to quantify corticospinal recruitment of spinal motor neurons serving paretic and non-paretic intrinsic hand muscles of humans with longstanding motor impairment secondary to stroke (n = 13). We also examined whether recruitment failures could be transiently reversed by strengthening corticospinal-motoneuronal synaptic connectivity via targeted, temporally controlled non-invasive stimulation to elicit spike timing-dependent plasticity (STDP). Asymmetries were detected in corticospinal recruitment of spinal motor neurons, central conduction time and motor-evoked potential (MEP) latency. However, only recruitment asymmetry correlated with maximal voluntary motor output from the paretic hand. STDP-like effects were observed as an increase in spinal motor neuron recruitment. Control experiments to isolate the locus of plasticity demonstrated a modulation in MEPs elicited by electrical stimulation of primary motor cortex but not F-wave size or persistence, suggesting that plasticity was mediated through enhanced efficacy of residual corticospinal-motor neuronal synapses. The modulation in recruitment was strongly associated with baseline recruitment asymmetry and impairment severity. Our findings demonstrate that asymmetry in corticospinal recruitment of spinal motor neurons is directly related to impairments experienced by stroke survivors. These recruitment deficits may be partially and transiently reversed by spike timing-dependent plasticity of synapses between upper and lower motor neurons in the spinal cord, downstream of supraspinal circuits damaged by stroke.


Assuntos
Córtex Motor , Acidente Vascular Cerebral , Potencial Evocado Motor , Humanos , Neurônios Motores , Músculo Esquelético , Plasticidade Neuronal , Tratos Piramidais , Sobreviventes , Estimulação Magnética Transcraniana
3.
J Neurophysiol ; 126(6): 2104-2118, 2021 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-34788156

RESUMO

Motor neurons convey information about motor intent that can be extracted and interpreted to control assistive devices. However, most methods for measuring the firing activity of single neurons rely on implanted microelectrodes. Although intracortical brain-computer interfaces (BCIs) have been shown to be safe and effective, the requirement for surgery poses a barrier to widespread use that can be mitigated by instead using noninvasive interfaces. The objective of this study was to evaluate the feasibility of deriving motor control signals from a wearable sensor that can detect residual motor unit activity in paralyzed muscles after chronic cervical spinal cord injury (SCI). Despite generating no observable hand movement, volitional recruitment of motor units below the level of injury was observed across attempted movements of individual fingers and overt wrist and elbow movements. Subgroups of motor units were coactive during flexion or extension phases of the task. Single digit movement intentions were classified offline from the electromyogram (EMG) power [root-mean-square (RMS)] or motor unit firing rates with median classification accuracies >75% in both cases. Simulated online control of a virtual hand was performed with a binary classifier to test feasibility of real-time extraction and decoding of motor units. The online decomposition algorithm extracted motor units in 1.2 ms, and the firing rates predicted the correct digit motion 88 ± 24% of the time. This study provides the first demonstration of a wearable interface for recording and decoding firing rates of motor units below the level of injury in a person with motor complete SCI.NEW & NOTEWORTHY A wearable electrode array and machine learning methods were used to record and decode myoelectric signals and motor unit firing in paralyzed muscles of a person with motor complete tetraplegia. The myoelectric activity and motor unit firing rates were task specific, even in the absence of visible motion, enabling accurate classification of attempted single-digit movements. This wearable system has the potential to enable people with tetraplegia to control assistive devices through movement intent.


Assuntos
Mãos/fisiopatologia , Músculo Esquelético/fisiopatologia , Reabilitação Neurológica/instrumentação , Quadriplegia , Recrutamento Neurofisiológico/fisiologia , Traumatismos da Medula Espinal , Dispositivos Eletrônicos Vestíveis , Adulto , Eletromiografia , Estudos de Viabilidade , Humanos , Aprendizado de Máquina , Masculino , Reabilitação Neurológica/métodos , Quadriplegia/etiologia , Quadriplegia/fisiopatologia , Quadriplegia/reabilitação , Traumatismos da Medula Espinal/complicações , Traumatismos da Medula Espinal/fisiopatologia , Traumatismos da Medula Espinal/reabilitação
4.
Cereb Cortex ; 30(10): 5400-5409, 2020 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-32494819

RESUMO

Motor commands for the arm and hand generally arise from the contralateral motor cortex, where most of the relevant corticospinal tract originates. However, the ipsilateral motor cortex shows activity related to arm movement despite the lack of direct connections. The extent to which the activity related to ipsilateral movement is independent from that related to contralateral movement is unclear based on conflicting conclusions in prior work. Here we investigate bilateral arm and hand movement tasks completed by two human subjects with intracortical microelectrode arrays implanted in the left hand and arm area of the motor cortex. Neural activity was recorded while they attempted to perform arm and hand movements in a virtual environment. This enabled us to quantify the strength and independence of motor cortical activity related to continuous movements of each arm. We also investigated the subjects' ability to control both arms through a brain-computer interface. Through a number of experiments, we found that ipsilateral arm movement was represented independently of, but more weakly than, contralateral arm movement. However, the representation of grasping was correlated between the two hands. This difference between hand and arm representation was unexpected and poses new questions about the different ways the motor cortex controls the hands and arms.


Assuntos
Córtex Motor/fisiologia , Movimento , Neurônios/fisiologia , Adulto , Braço/fisiologia , Interfaces Cérebro-Computador , Feminino , Lateralidade Funcional , Mãos/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade
5.
Neurobiol Dis ; 121: 286-295, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30217521

RESUMO

Motor output maps within primary motor cortex are widely distributed and modified by motor skill learning and neurological injury. Functions that these maps represent after spinal cord injury remain debatable. Moreover, the pattern of reorganization and whether it supports recovery of compromised motor function is not well understood. A deeper understanding of the pathophysiological mechanisms of motor dysfunction after spinal cord injury is necessary to develop and optimize repair strategies. There are three purposes for this review. The first is to synthesize available research on spontaneous reorganization with primary motor cortex following spinal cord injury. The second is to draw on existing evidence from the motor skill learning and brain injury literature to interpret the form and purpose of motor maps. The third purpose is to account for the existing research on intervention-induced reorganization of primary motor cortex following spinal cord injury. We conclude with directions for future work, emphasizing the need for multi-modal investigations that construct maps with both neuroimaging and non-invasive stimulation methods to derive a cohesive understanding of the effects of spinal cord injury on reorganization within primary motor cortex.


Assuntos
Córtex Motor/fisiopatologia , Plasticidade Neuronal , Traumatismos da Medula Espinal/fisiopatologia , Animais , Humanos , Aprendizagem/fisiologia , Destreza Motora/fisiologia , Recuperação de Função Fisiológica , Traumatismos da Medula Espinal/reabilitação
6.
J Neurophysiol ; 118(4): 2412-2420, 2017 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28768745

RESUMO

After paralysis, the disconnection between the cortex and its peripheral targets leads to neuroplasticity throughout the nervous system. However, it is unclear how chronic paralysis specifically impacts cortical oscillations associated with attempted movement of impaired limbs. We hypothesized that µ- (8-13 Hz) and ß- (15-30 Hz) event-related desynchronization (ERD) would be less modulated for individuals with hand paralysis due to cervical spinal cord injury (SCI). To test this, we compared the modulation of ERD from magnetoencephalography (MEG) during attempted and imagined grasping performed by participants with cervical SCI (n = 12) and able-bodied controls (n = 13). Seven participants with tetraplegia were able to generate some electromyography (EMG) activity during attempted grasping, whereas the other five were not. The peak and area of ERD were significantly decreased for individuals without volitional muscle activity when they attempted to grasp compared with able-bodied subjects and participants with SCI,with some residual EMG activity. However, no significant differences were found between subject groups during mentally simulated tasks (i.e., motor imagery) where no muscle activity or somatosensory consequences were expected. These findings suggest that individuals who are unable to produce muscle activity are capable of generating ERD when attempting to move, but the characteristics of this ERD are altered. However, for people who maintain volitional muscle activity after SCI, there are no significant differences in ERD characteristics compared with able-bodied controls. These results provide evidence that ERD is dependent on the level of intact muscle activity after SCI.NEW & NOTEWORTHY Source space MEG was used to investigate sensorimotor cortical oscillations in individuals with SCI. This study provides evidence that individuals with cervical SCI exhibit decreased ERD when they attempt to grasp if they are incapable of generating muscle activity. However, there were no significant differences in ERD between paralyzed and able-bodied participants during motor imagery. These results have important implications for the design and evaluation of new therapies, such as motor imagery and neurofeedback interventions.


Assuntos
Ritmo beta , Sincronização Cortical , Paralisia/fisiopatologia , Córtex Sensório-Motor/fisiopatologia , Traumatismos da Medula Espinal/fisiopatologia , Adolescente , Adulto , Estudos de Casos e Controles , Criança , Pré-Escolar , Potencial Evocado Motor , Potenciais Somatossensoriais Evocados , Retroalimentação Fisiológica , Feminino , Força da Mão , Humanos , Masculino , Contração Muscular , Paralisia/etiologia , Traumatismos da Medula Espinal/complicações
7.
J Neuroeng Rehabil ; 13: 28, 2016 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-26987662

RESUMO

BACKGROUND: Recent studies have shown that brain-machine interfaces (BMIs) offer great potential for restoring upper limb function. However, grasping objects is a complicated task and the signals extracted from the brain may not always be capable of driving these movements reliably. Vision-guided robotic assistance is one possible way to improve BMI performance. We describe a method of shared control where the user controls a prosthetic arm using a BMI and receives assistance with positioning the hand when it approaches an object. METHODS: Two human subjects with tetraplegia used a robotic arm to complete object transport tasks with and without shared control. The shared control system was designed to provide a balance between BMI-derived intention and computer assistance. An autonomous robotic grasping system identified and tracked objects and defined stable grasp positions for these objects. The system identified when the user intended to interact with an object based on the BMI-controlled movements of the robotic arm. Using shared control, BMI controlled movements and autonomous grasping commands were blended to ensure secure grasps. RESULTS: Both subjects were more successful on object transfer tasks when using shared control compared to BMI control alone. Movements made using shared control were more accurate, more efficient, and less difficult. One participant attempted a task with multiple objects and successfully lifted one of two closely spaced objects in 92 % of trials, demonstrating the potential for users to accurately execute their intention while using shared control. CONCLUSIONS: Integration of BMI control with vision-guided robotic assistance led to improved performance on object transfer tasks. Providing assistance while maintaining generalizability will make BMI systems more attractive to potential users. TRIAL REGISTRATION: NCT01364480 and NCT01894802 .


Assuntos
Interfaces Cérebro-Computador , Reabilitação Neurológica/instrumentação , Quadriplegia , Robótica/métodos , Extremidade Superior , Adulto , Encéfalo/fisiopatologia , Feminino , Mãos/fisiopatologia , Força da Mão , Humanos , Masculino , Pessoa de Meia-Idade , Movimento , Quadriplegia/fisiopatologia , Extremidade Superior/fisiopatologia
8.
J Neuroeng Rehabil ; 12: 85, 2015 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-26392353

RESUMO

BACKGROUND: Providing neurofeedback (NF) of motor-related brain activity in a biologically-relevant and intuitive way could maximize the utility of a brain-computer interface (BCI) for promoting therapeutic plasticity. We present a BCI capable of providing intuitive and direct control of a video-based grasp. METHODS: Utilizing magnetoencephalography's (MEG) high temporal and spatial resolution, we recorded sensorimotor rhythms (SMR) that were modulated by grasp or rest intentions. SMR modulation controlled the grasp aperture of a stop motion video of a human hand. The displayed hand grasp position was driven incrementally towards a closed or opened state and subjects were required to hold the targeted position for a time that was adjusted to change the task difficulty. RESULTS: We demonstrated that three individuals with complete hand paralysis due to spinal cord injury (SCI) were able to maintain brain-control of closing and opening a virtual hand with an average of 63 % success which was significantly above the average chance rate of 19 %. This level of performance was achieved without pre-training and less than 4 min of calibration. In addition, successful grasp targets were reached in 1.96 ± 0.15 s. Subjects performed 200 brain-controlled trials in approximately 30 min excluding breaks. Two of the three participants showed a significant improvement in SMR indicating that they had learned to change their brain activity within a single session of NF. CONCLUSIONS: This study demonstrated the utility of a MEG-based BCI system to provide realistic, efficient, and focused NF to individuals with paralysis with the goal of using NF to induce neuroplasticity.


Assuntos
Interfaces Cérebro-Computador , Magnetoencefalografia/métodos , Neurorretroalimentação/métodos , Traumatismos da Medula Espinal/reabilitação , Adulto , Feminino , Humanos , Masculino
9.
Lancet ; 381(9866): 557-64, 2013 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-23253623

RESUMO

BACKGROUND: Paralysis or amputation of an arm results in the loss of the ability to orient the hand and grasp, manipulate, and carry objects, functions that are essential for activities of daily living. Brain-machine interfaces could provide a solution to restoring many of these lost functions. We therefore tested whether an individual with tetraplegia could rapidly achieve neurological control of a high-performance prosthetic limb using this type of an interface. METHODS: We implanted two 96-channel intracortical microelectrodes in the motor cortex of a 52-year-old individual with tetraplegia. Brain-machine-interface training was done for 13 weeks with the goal of controlling an anthropomorphic prosthetic limb with seven degrees of freedom (three-dimensional translation, three-dimensional orientation, one-dimensional grasping). The participant's ability to control the prosthetic limb was assessed with clinical measures of upper limb function. This study is registered with ClinicalTrials.gov, NCT01364480. FINDINGS: The participant was able to move the prosthetic limb freely in the three-dimensional workspace on the second day of training. After 13 weeks, robust seven-dimensional movements were performed routinely. Mean success rate on target-based reaching tasks was 91·6% (SD 4·4) versus median chance level 6·2% (95% CI 2·0-15·3). Improvements were seen in completion time (decreased from a mean of 148 s [SD 60] to 112 s [6]) and path efficiency (increased from 0·30 [0·04] to 0·38 [0·02]). The participant was also able to use the prosthetic limb to do skilful and coordinated reach and grasp movements that resulted in clinically significant gains in tests of upper limb function. No adverse events were reported. INTERPRETATION: With continued development of neuroprosthetic limbs, individuals with long-term paralysis could recover the natural and intuitive command signals for hand placement, orientation, and reaching, allowing them to perform activities of daily living. FUNDING: Defense Advanced Research Projects Agency, National Institutes of Health, Department of Veterans Affairs, and UPMC Rehabilitation Institute.


Assuntos
Membros Artificiais , Interfaces Cérebro-Computador , Quadriplegia/terapia , Braço , Feminino , Força da Mão , Humanos , Microeletrodos , Pessoa de Meia-Idade , Desempenho Psicomotor
10.
bioRxiv ; 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39131333

RESUMO

As brain-computer interface (BCI) research advances, many new applications are being developed. Tasks can be performed in different environments, and whether a BCI user can switch environments seamlessly will influence the ultimate utility of a clinical device. Here we investigate the importance of the immersiveness of the virtual environment used to train BCI decoders on the resulting decoder and its generalizability between environments. Two participants who had intracortical electrodes implanted in their precentral gyrus used a BCI to control a virtual arm, either viewed immersively through virtual reality goggles or at a distance on a flat television monitor. Each participant performed better with a decoder trained and tested in the environment they had used the most prior to the study, one for each environment type. The neural tuning to the desired movement was minimally influenced by the immersiveness of the environment. Finally, in further testing with one of the participants, we found that decoders trained in one environment generalized well to the other environment, but the order in which the environments were experienced within a session mattered. Overall, experience with an environment was more influential on performance than the immersiveness of the environment, but BCI performance generalized well after accounting for experience.

11.
Nat Hum Behav ; 8(4): 729-742, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38287177

RESUMO

The most prominent characteristic of motor cortex is its activation during movement execution, but it is also active when we simply imagine movements in the absence of actual motor output. Despite decades of behavioural and imaging studies, it is unknown how the specific activity patterns and temporal dynamics in motor cortex during covert motor imagery relate to those during motor execution. Here we recorded intracortical activity from the motor cortex of two people who retain some residual wrist function following incomplete spinal cord injury as they performed both actual and imagined isometric wrist extensions. We found that we could decompose the population activity into three orthogonal subspaces, where one was similarly active during both action and imagery, and the others were active only during a single task type-action or imagery. Although they inhabited orthogonal neural dimensions, the action-unique and imagery-unique subspaces contained a strikingly similar set of dynamic features. Our results suggest that during motor imagery, motor cortex maintains the same overall population dynamics as during execution by reorienting the components related to motor output and/or feedback into a unique, output-null imagery subspace.


Assuntos
Imaginação , Córtex Motor , Humanos , Córtex Motor/fisiologia , Córtex Motor/diagnóstico por imagem , Imaginação/fisiologia , Masculino , Traumatismos da Medula Espinal/fisiopatologia , Adulto , Movimento/fisiologia , Feminino , Punho/fisiologia , Atividade Motora/fisiologia , Pessoa de Meia-Idade , Desempenho Psicomotor/fisiologia
12.
medRxiv ; 2024 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-38712177

RESUMO

Intracortical microstimulation (ICMS) is a method for restoring sensation to people with paralysis as part of a bidirectional brain-computer interface to restore upper limb function. Evoking tactile sensations of the hand through ICMS requires precise targeting of implanted electrodes. Here we describe the presurgical imaging procedures used to generate functional maps of the hand area of the somatosensory cortex and subsequent planning that guided the implantation of intracortical microelectrode arrays. In five participants with cervical spinal cord injury, across two study locations, this procedure successfully enabled ICMS-evoked sensations localized to at least the first four digits of the hand. The imaging and planning procedures developed through this clinical trial provide a roadmap for other brain-computer interface studies to ensure successful placement of stimulation electrodes.

13.
J Spinal Cord Med ; 36(4): 258-72, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23820142

RESUMO

CONTEXT: Spinal cord injury (SCI) results in a loss of function and sensation below the level of the lesion. Neuroprosthetic technology has been developed to help restore motor and autonomic functions as well as to provide sensory feedback. FINDINGS: This paper provides an overview of neuroprosthetic technology that aims to address the priorities for functional restoration as defined by individuals with SCI. We describe neuroprostheses that are in various stages of preclinical development, clinical testing, and commercialization including functional electrical stimulators, epidural and intraspinal microstimulation, bladder neuroprosthesis, and cortical stimulation for restoring sensation. We also discuss neural recording technologies that may provide command or feedback signals for neuroprosthetic devices. CONCLUSION/CLINICAL RELEVANCE: Neuroprostheses have begun to address the priorities of individuals with SCI, although there remains room for improvement. In addition to continued technological improvements, closing the loop between the technology and the user may help provide intuitive device control with high levels of performance.


Assuntos
Próteses e Implantes , Recuperação de Função Fisiológica , Traumatismos da Medula Espinal/reabilitação , Interfaces Cérebro-Computador , Terapia por Estimulação Elétrica/instrumentação , Terapia por Estimulação Elétrica/métodos , Eletromiografia/instrumentação , Eletromiografia/métodos , Retroalimentação Fisiológica , Humanos , Traumatismos da Medula Espinal/fisiopatologia , Bexiga Urinária/fisiopatologia
14.
bioRxiv ; 2023 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-37781630

RESUMO

The neural population spiking activity recorded by intracortical brain-computer interfaces (iBCIs) contain rich structure. Current models of such spiking activity are largely prepared for individual experimental contexts, restricting data volume to that collectable within a single session and limiting the effectiveness of deep neural networks (DNNs). The purported challenge in aggregating neural spiking data is the pervasiveness of context-dependent shifts in the neural data distributions. However, large scale unsupervised pretraining by nature spans heterogeneous data, and has proven to be a fundamental recipe for successful representation learning across deep learning. We thus develop Neural Data Transformer 2 (NDT2), a spatiotemporal Transformer for neural spiking activity, and demonstrate that pretraining can leverage motor BCI datasets that span sessions, subjects, and experimental tasks. NDT2 enables rapid adaptation to novel contexts in downstream decoding tasks and opens the path to deployment of pretrained DNNs for iBCI control. Code: https://github.com/joel99/context_general_bci.

15.
iScience ; 26(4): 106518, 2023 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-37070071

RESUMO

A spatiotemporal pattern of excitability propagates across the primary motor cortex prior to the onset of a reaching movement in non-human primates. If this pattern is a necessary component of voluntary movement initiation, it should be present across a variety of motor tasks, end-effectors, and even species. Here, we show that propagating patterns of excitability occur during the initiation of precision grip force and tongue protrusion in non-human primates, and even isometric wrist extension in a human participant. In all tasks, the directions of propagation across the cortical sheet were bimodally distributed across trials with modes oriented roughly opposite to one another. Propagation speed was unimodally distributed with similar mean speeds across tasks and species. Additionally, propagation direction and speed did not vary systematically with any behavioral measures except response times indicating that this propagating pattern is invariant to kinematic or kinetic details and may be a generic movement initiation signal.

16.
Assist Technol ; 35(3): 258-270, 2023 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-34982647

RESUMO

Existing prosthetic technologies for people with upper limb amputation are being adopted at moderate rates. Once fitted for these devices, many upper limb amputees report not using them regularly or at all. The primary aim of this study was to solicit feedback about prosthetic technology and important device design criteria from amputees, clinicians, and device regulators. We compare these perspectives to identify common or divergent priorities. Twenty-one adults with upper limb loss, 35 clinicians, and 3 regulators completed a survey on existing prosthetic technologies and a conceptual sensorimotor prosthesis driven by implanted myoelectric electrodes with sensory feedback via spinal root stimulation. The survey included questions from the Trinity Amputation and Prosthesis Experience Scale, the Disabilities of the Arm, Shoulder, and Hand, and novel questions about technology acceptance and neuroprosthetic design. User and clinician ratings of satisfaction with existing devices were similar. Amputees were most accepting of the proposed sensorimotor prosthesis (75.5% vs clinicians (68.8%), regulators (67.8%)). Stakeholders valued user-centered outcomes like individualized task goals, improved quality of life, device reliability, and user safety; regulators emphasized these last two. The results of this study provide insight into amputee, clinician, and regulator priorities to inform future upper-limb prosthetic design and clinical trial protocol development.


Assuntos
Amputados , Membros Artificiais , Adulto , Humanos , Qualidade de Vida , Reprodutibilidade dos Testes , Estudos Prospectivos , Extremidade Superior/cirurgia , Desenho de Prótese
17.
bioRxiv ; 2023 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-36711675

RESUMO

The most prominent role of motor cortex is generating patterns of neural activity that lead to movement, but it is also active when we simply imagine movements in the absence of actual motor output. Despite decades of behavioral and imaging studies, it is unknown how the specific activity patterns and temporal dynamics within motor cortex during covert motor imagery relate to those during motor execution. Here we recorded intracortical activity from the motor cortex of two people with residual wrist function following incomplete spinal cord injury as they performed both actual and imagined isometric wrist extensions. We found that we could decompose the population-level activity into orthogonal subspaces such that one set of components was similarly active during both action and imagery, and others were only active during a single task typeâ€"action or imagery. Although they inhabited orthogonal neural dimensions, the action-unique and imagery-unique subspaces contained a strikingly similar set of dynamical features. Our results suggest that during motor imagery, motor cortex maintains the same overall population dynamics as during execution by recreating the missing components related to motor output and/or feedback within a unique imagery-only subspace.

18.
Front Neurosci ; 17: 1104419, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36968482

RESUMO

Neural engineering is an emerging and multidisciplinary field in which engineering approaches are applied to neuroscience problems. Women are underrepresented in engineering fields, and indeed in science, technology, engineering, and mathematics (STEM) fields generally. Underrepresentation of women is particularly notable at later academic career stages, suggesting that even though women are interested in the field, barriers exist that ultimately cause them to leave. Here, we investigate many of the obstacles to women's success in the field of neural engineering and provide recommendations and materials to overcome them. We conducted a review of the literature from the past 15 years regarding the experiences of women in academic careers, as well as reports on the number of women in fields closely related to neural engineering from the National Science Foundation (NSF) and the American Society for Engineering Education (ASEE). Additionally, we interviewed six women in neural engineering who are involved in initiatives and outreach concerning the inclusion and experiences of women in engineering. Throughout the literature and interviews, we identified common themes spanning the role of identity and confidence, professional relationships, career-related hurdles, and personal and professional expectations. We explore each of these themes in detail and provide resources to support the growth of women as they climb within the field of neural engineering.

19.
Neuroimage Clin ; 38: 103398, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37086647

RESUMO

Stability of precision grip depends on the ability to regulate forces applied by the digits. Increased frequency composition and temporal irregularity of oscillations in the force signal are associated with enhanced force stability, which is thought to result from increased voluntary drive along the corticospinal tract (CST). There is limited knowledge of how these oscillations in force output are regulated in the context of dexterous hand movements like precision grip, which are often impaired by CST damage due to stroke. The extent of residual CST volume descending from primary motor cortex may help explain the ability to modulate force oscillations at higher frequencies. Here, stroke survivors with longstanding hand impairment (n = 17) and neurologically-intact controls (n = 14) performed a precision grip task requiring dynamic and isometric muscle contractions to scale and stabilize forces exerted on a sensor by the index finger and thumb. Diffusion spectrum imaging was used to quantify total white matter volume within the residual and intact CSTs of stroke survivors (n = 12) and CSTs of controls (n = 14). White matter volumes within the infarct region and an analogous portion of overlap with the CST, mirrored onto the intact side, were also quantified in stroke survivors. We found reduced ability to stabilize force and more restricted frequency ranges in force oscillations of stroke survivors relative to controls; though, more broadband, irregular output was strongly related to force-stabilizing ability in both groups. The frequency composition and temporal irregularity of force oscillations observed in stroke survivors did not correlate with maximal precision grip force, suggesting that it is not directly related to impaired force-generating capacity. The ratio of residual to intact CST volumes contained within infarct and mirrored compartments was associated with more broadband, irregular force oscillations in stroke survivors. Our findings provide insight into granular aspects of dexterity altered by corticospinal damage and supply preliminary evidence to support that the ability to modulate force oscillations at higher frequencies is explained, at least in part, by residual CST volume in stroke survivors.


Assuntos
Tratos Piramidais , Acidente Vascular Cerebral , Humanos , Tratos Piramidais/diagnóstico por imagem , Dedos , Força da Mão/fisiologia , Infarto
20.
Neuron ; 111(23): 3710-3715, 2023 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-37944519

RESUMO

Sharing human brain data can yield scientific benefits, but because of various disincentives, only a fraction of these data is currently shared. We profile three successful data-sharing experiences from the NIH BRAIN Initiative Research Opportunities in Humans (ROH) Consortium and demonstrate benefits to data producers and to users.


Assuntos
Encéfalo , Neurofisiologia , Humanos , Disseminação de Informação
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