Validity and Impact of Methods for Collecting Training Data for Myoelectric Prosthetic Control Algorithms.

Intuitive regression control of prostheses relies on training algorithms to correlate biological recordings to motor intent. The quality of the training dataset is critical to run-time regression performance, but accurately labeling intended hand kinematics after hand amputation is challenging. In this study, we quantified the accuracy and precision of labeling hand kinematics using two common training paradigms: 1) mimic training, where participants mimic predetermined motions of a prosthesis, and 2) mirror training, where participants mirror their contralateral intact hand during synchronized bilateral movements. We first explored this question in healthy non-amputee individuals where the ground-truth kinematics could be readily determined using motion capture. Kinematic data showed that mimic training fails to account for biomechanical coupling and temporal changes in hand posture. Additionally, mirror training exhibited significantly higher accuracy and precision in labeling hand kinematics. These findings suggest that the mirror training approach generates a more faithful, albeit more complex, dataset. Accordingly, mirror training resulted in significantly better offline regression performance when using a large amount of training data and a non-linear neural network. Next, we explored these different training paradigms online, with a cohort of unilateral transradial amputees actively controlling a prosthesis in real-time to complete a functional task. Overall, we found that mirror training resulted in significantly faster task completion speeds and similar subjective workload. These results demonstrate that mirror training can potentially provide more dexterous control through the utilization of task-specific, user-selected training data. Consequently, these findings serve as a valuable guide for the next generation of myoelectric and neuroprostheses leveraging machine learning to provide more dexterous and intuitive control.

How did the European Marriage Pattern persist? Social versus familial inheritance: England and Quebec, 1650-1850.

The European Marriage Pattern (EMP), in place in NW Europe for perhaps 500 years, substantially limited fertility. But how could such limitation persist when some individuals who deviated from the EMP norm had more children? If their children inherited their deviant behaviors, their descendants would quickly become the majority of later generations. This puzzle has two possible solutions. The first is that all those that deviated actually had lower net fertility over multiple generations. We show, however, no fertility penalty to future generations from higher initial fertility. Instead the EMP survived because even though the EMP persisted at the social level, children did not inherit their parents' individual fertility choices. In the paper we show evidence consistent with lateral, as opposed to vertical, transmission of EMP fertility behaviors.

Treatment options for symptomatic knee osteoarthritis in adults.

ABSTRACT: Knee osteoarthritis is a common medical condition in adults, especially among older adults. The incidence and prevalence of knee osteoarthritis are increasing, and many healthcare providers manage patients with symptomatic presentations. This article reviews the most common nonsurgical and surgical treatment options for knee osteoarthritis, emphasizing evidence-based and practical therapies.

A Retrospective Analysis of the Clinical Use and Utility of Advanced Imaging in the Evaluation of Near-Hanging and Strangulation Injuries at a Canadian Level One Trauma Centre.

INTRODUCTION: Computed tomography (CT) of the neck is highly sensitive and may effectively rule-out cervical spine, cerebrovascular, and aerodigestive injuries after blunt and penetrating trauma. However, CT may be overutilized in the evaluation of hanging or strangulation injuries. The objective of this study was to determine the diagnostic yield of CT imaging among patients evaluated for hanging or strangulation mechanisms at a Canadian level-1 trauma center. METHODS: All adult patients evaluated for hanging or strangulation injuries over an eight-year period were reviewed. The primary outcome was the diagnostic yield of CT imaging for major aerodigestive, cervical spine, cerebrovascular, or neurological injuries. Multiple logistic regression were performed to determine predictive factors for the use of CT imaging and the identification of injury on imaging. RESULTS: Among 124 patients evaluated for hanging or strangulation injuries during the study period, 101 (80%) were evaluated with CT of the head or neck. A total of 26 injuries were identified in 21 patients (18 anoxic brain injuries, 4 aerodigestive, 3 cerebrovascular, and 1 of cervical spine injury). The overall diagnostic yield of neck CT for cervical injuries was 7.8%, 4.7% for laryngeal-tracheal injuries, 3.5% for carotid and vertebral artery injuries, and 1.1% for cervical spine injury. The diagnostic yield of CT head for anoxic brain injury was 22.8%. Factors predicting the use of CT imaging were abnormal physical exam findings (RR 1.7 95% CI [1.2, 2.3]) and transfer accepted by the trauma team leader (RR 1.3 95% CI [1.1, 1.5]). CONCLUSION: CT imaging is often used in the evaluation of patients presenting with hanging or strangulation mechanisms. Seven cerebrovascular, aerodigestive, or cervical spine injuries were identified on imaging during the study period, representing a diagnostic yield of 7%. No injuries were identified among patient with a normal GCS or physical exam. Factors predicting the use of CT imaging included transfer accepted by the trauma team leader and abnormal physical exam findings. The variable clinical presentation of near-hanging and strangulation injuries and the relatively low diagnostic yield of CT imaging should prompt the development of tools and institutional protocols to guide the evaluation of hanging and strangulation injuries.

Non-invasive central nervous system assessment of a porcine model of neuropathic pain demonstrates increased latency of somatosensory-evoked potentials.

BACKGROUND: The study of chronic pain and its treatments requires a robust animal model with objective and quantifiable metrics. Porcine neuropathic pain models have been assessed with peripheral pain recordings and behavioral responses, but thus far central nervous system electrophysiology has not been investigated. This work aimed to record non-invasive, somatosensory-evoked potentials (SEPs) via electroencephalography in order to quantitatively assess chronic neuropathic pain induced in a porcine model. NEW METHOD: Peripheral neuritis trauma (PNT) was induced unilaterally in the common peroneal nerve of domestic farm pigs, with the contralateral leg serving as the control for each animal. SEPs were generated by stimulation of the peripheral nerves distal to the PNT and were recorded non-invasively using transcranial electroencephalography (EEG). The P30 wave of the SEP was analyzed for latency changes. RESULTS: P30 SEPs were successfully recorded with non-invasive EEG. PNT resulted in significantly longer P30 SEP latencies (p < 0.01 [n = 8]) with a median latency increase of 14.3 [IQR 5.0 - 17.5] ms. Histological results confirmed perineural inflammatory response and nerve damage around the PNT nerves. COMPARISON WITH EXISTING METHOD(S): Control P30 SEPs were similar in latency and amplitude to those previously recorded invasively in healthy pigs. Non-invasive recordings have numerous advantages over invasive measures. CONCLUSIONS: P30 SEP latency can serve as a quantifiable neurological measure that reflects central nervous system processing in a porcine model of chronic pain. Advancing the development of a porcine chronic pain model will facilitate the translation of experimental therapies into human clinical trials.

Accuracy of Self-Reported COVID-19 Vaccination Status Compared With a Public Health Vaccination Registry in Québec: Observational Diagnostic Study.

BACKGROUND: The accuracy of self-reported vaccination status is important to guide real-world vaccine effectiveness studies and policy making in jurisdictions where access to electronic vaccine registries is restricted. OBJECTIVE: This study aimed to determine the accuracy of self-reported vaccination status and reliability of the self-reported number of doses, brand, and time of vaccine administration. METHODS: This diagnostic accuracy study was completed by the Canadian COVID-19 Emergency Department Rapid Response Network. We enrolled consecutive patients presenting to 4 emergency departments (EDs) in Québec between March 24, 2020, and December 25, 2021. We included adult patients who were able to consent, could speak English or French, and had a proven COVID-19 infection. We compared the self-reported vaccination status of the patients with their vaccination status in the electronic Québec Vaccination Registry. Our primary outcome was the accuracy of the self-reported vaccination status (index test) ascertained during telephone follow-up compared with the Québec Vaccination Registry (reference standard). The accuracy was calculated by dividing all correctly self-reported vaccinated and unvaccinated participants by the sum of all correctly and incorrectly self-reported vaccinated and unvaccinated participants. We also reported interrater agreement with the reference standard as measured by unweighted Cohen κ for self-reported vaccination status at telephone follow-up and at the time of their index ED visit, number of vaccine doses, and brand. RESULTS: During the study period, we included 1361 participants. At the time of the follow-up interview, 932 participants reported at least 1 dose of a COVID-19 vaccine. The accuracy of the self-reported vaccination status was 96% (95% CI 95%-97%). Cohen κ for self-reported vaccination status at phone follow-up was 0.91 (95% CI 0.89-0.93) and 0.85 (95% CI 0.77-0.92) at the time of their index ED visit. Cohen κ was 0.89 (95% CI 0.87-0.91) for the number of doses, 0.80 (95% CI 0.75-0.84) for the brand of the first dose, 0.76 (95% CI 0.70-0.83) for the brand of the second dose, and 0.59 (95% CI 0.34-0.83) for the brand of the third dose. CONCLUSIONS: We reported a high accuracy of self-reported vaccination status for adult patients without cognitive disorders who can express themselves in English or French. Researchers can use self-reported COVID-19 vaccination data on the number of doses received, vaccine brand name, and timing of vaccination to guide future research with patients who are capable of self-reporting their vaccination data. However, access to official electronic vaccine registries is still needed to determine the vaccination status in certain susceptible populations where self-reported vaccination data remain missing or impossible to obtain. TRIAL REGISTRATION: Clinicaltrials.gov NCT04702945; https://clinicaltrials.gov/ct2/show/NCT04702945.

The inheritance of social status: England, 1600 to 2022.

A lineage of 422,374 English people (1600 to 2022) contains correlations in social outcomes among relatives as distant as 4th cousins. These correlations show striking patterns. The first is the strong persistence of social status across family trees. Correlations decline by a factor of only 0.79 across each generation. Even fourth cousins, with a common ancestor only five generations earlier, show significant status correlations. The second remarkable feature is that the decline in correlation with genetic distance in the lineage is unchanged from 1600 to 2022. Vast social changes in England between 1600 and 2022 would have been expected to increase social mobility. Yet people in 2022 remain correlated in outcomes with their lineage relatives in exactly the same way as in preindustrial England. The third surprising feature is that the correlations parallel those of a simple model of additive genetic determination of status, with a genetic correlation in marriage of 0.57.

Feasibility of non-invasive recording of somatosensory evoked potential in pigs.

BACKGROUND: Non-invasive measurement of somatosensory-evoked potentials (SEP) in a large animal model is important to translational cognitive research. We sought to develop a methodology for neurophysiological recording via a transcranial electroencephalography (EEG) cap under an effective sedative regimen with dexmedetomidine, midazolam, and butorphanol that will produce sedation instead of anesthesia while not compromising data quality. RESULTS: Pigs received intramuscular dexmedetomidine, midazolam, and butorphanol for SEP assessment with peroneal nerve stimulation. Semi-quantitative sedation assessment was performed after the animal was sufficiently sedated and 30 min later, during the transcranial SEP recording. SEP data were analyzed with commercial software. Binary qualitative analysis of the recording was categorized by an experienced neurophysiologist. All four animals had adequate surface SEP recordings. Animals received 43 [21-47] mcg/kg of dexmedetomidine, 0.3 [0.2-0.3] mg/kg of midazolam, and 0.3 [0.3-0.3] mg/kg of butorphanol IM. All treatments resulted in moderate to deep sedation (Baseline median sedation score 11.5 [11-12]; median score at 30 min: 11.5 [10.5-12]). Heart rate (median [range]) (55 [49-71] beats per minute), respiratory rate (24 [21-30] breaths per minute), and hemoglobin oxygen saturation (99 [98-100]%) and body temperature (37.7 [37.4-37.9] °C) remained within clinically acceptable ranges. There were no undesirable recovery incidents. CONCLUSIONS: In this pilot study, we demonstrate the feasibility of SEP recording via a transcranial EEG cap under an effective sedative regimen in pigs. Our approach will expand the use of a large animal model in neurotranslational research.

The CCEDRRN COVID-19 Mortality Score to predict death among nonpalliative patients with COVID-19 presenting to emergency departments: a derivation and validation study.

BACKGROUND: Predicting mortality from COVID-19 using information available when patients present to the emergency department can inform goals-of-care decisions and assist with ethical allocation of critical care resources. The study objective was to develop and validate a clinical score to predict emergency department and in-hospital mortality among consecutive nonpalliative patients with COVID-19; in this study, we define palliative patients as those who do not want resuscitative measures, such as intubation, intensive care unit care or cardiopulmonary resuscitation. METHODS: This derivation and validation study used observational cohort data recruited from 46 hospitals in 8 Canadian provinces participating in the Canadian COVID-19 Emergency Department Rapid Response Network (CCEDRRN). We included adult (age ≥ 18 yr) nonpalliative patients with confirmed COVID-19 who presented to the emergency department of a participating site between Mar. 1, 2020, and Jan. 31, 2021. We randomly assigned hospitals to derivation or validation, and prespecified clinical variables as candidate predictors. We used logistic regression to develop the score in a derivation cohort and examined its performance in predicting emergency department and in-hospital mortality in a validation cohort. RESULTS: Of 8761 eligible patients, 618 (7.0%) died. The CCEDRRN COVID-19 Mortality Score included age, sex, type of residence, arrival mode, chest pain, severe liver disease, respiratory rate and level of respiratory support. The area under the curve was 0.92 (95% confidence interval [CI] 0.90-0.93) in derivation and 0.92 (95% CI 0.90-0.93) in validation. The score had excellent calibration. These results suggest that scores of 6 or less would categorize patients as being at low risk for in-hospital death, with a negative predictive value of 99.9%. Patients in the low-risk group had an in-hospital mortality rate of 0.1%. Patients with a score of 15 or higher had an observed mortality rate of 81.0%. INTERPRETATION: The CCEDRRN COVID-19 Mortality Score is a simple score that can be used for level-of-care discussions with patients and in situations of critical care resource constraints to accurately predict death using variables available on emergency department arrival. The score was derived and validated mostly in unvaccinated patients, and before variants of concern were circulating widely and newer treatment regimens implemented in Canada. STUDY REGISTRATION: ClinicalTrials.gov, no. NCT04702945.

External validation of the updated Brain Injury Guidelines for complicated mild traumatic brain injuries: a retrospective cohort study.

OBJECTIVE: Approximately 10% of patients with mild traumatic brain injury (mTBI) have intracranial bleeding (complicated mTBI) and 3.5% eventually require neurosurgical intervention, which is mostly available at centers with a higher level of trauma care designation and often requires interhospital transfer. In 2018, the Brain Injury Guidelines (BIG) were updated in the United States to guide emergency department care and patient disposition for complicated mild to moderate TBI. The aim of this study was to validate the sensitivity and specificity of the updated BIG (uBIG) for predicting the need for interhospital transfer in Canadian patients with complicated mTBI. METHODS: This study took place at three level I trauma centers. Consecutive medical records of patients with complicated mTBI (Glasgow Coma Scale score 13-15) who were aged ≥ 16 years and presented between September 2016 and December 2017 were retrospectively reviewed. Patients with a penetrating trauma and those who had a documented cerebral tumor or aneurysm were excluded. The primary outcome was a combination of neurosurgical intervention and/or mTBI-related death. Sensitivity and specificity analyses were performed. RESULTS: A total of 477 patients were included, of whom 8.4% received neurosurgical intervention and 3% died as a result of their mTBI. Forty patients (8%) were classified as uBIG-1, 168 (35%) as uBIG-2, and 269 (56%) as uBIG-3. No patients in uBIG-1 underwent neurosurgical intervention or died as a result of their injury. This translates into a sensitivity for predicting the need for a transfer of 100% (95% CI 93.2%-100%) and a specificity of 9.4% (95% CI 6.8%-12.6%). Using the uBIG could potentially reduce the number of transfers by 6% to 25%. CONCLUSIONS: The patients in uBIG-1 could be safely managed at their initial center without the need for transfer to a center with a higher level of neurotrauma care. Although the uBIG could decrease the number of transfers, further refinement of the criteria could improve its specificity.

Social Mobility and Political Regimes: Intergenerational Mobility in Hungary, 1949-2017.

This paper measures social mobility rates in Hungary during the period 1949 to 2017, using surnames to measure social status. In those years, there were two very different social regimes. The first was the Hungarian People's Republic (1949-1989), which was a communist regime with an avowed aim of favouring the working class. The second is the modern liberal democracy (1989-2017), which is a free-market economy. We find five surprising things. First, social mobility rates were low for both upper- and lower-class families during 1949-2017, with an underlying intergenerational status correlation of 0.6-0.8. Second, social mobility rates under communism were the same as in the subsequent capitalist regime. Third, the Romani minority throughout both periods showed even lower social mobility rates. Fourth, the descendants of the eighteenth-century noble class in Hungary were still significantly privileged in 1949 and later. And fifth, although social mobility rates did not change measurably during the transition, the composition of the political elite changed rapidly and sharply.

A Recurrent Neural Network Provides Stable Across-Day Prosthetic Control for a Human Amputee with Implanted Intramuscular Electromyographic Recording Leads.

Upper-limb prosthetic control is often challenging and non-intuitive, leading to up to 50% of prostheses users abandoning their prostheses. Convolutional neural networks (CNN) and recurrent long short-term memory (LSTM) networks have shown promise in extracting high-degree-of-freedom motor intent from myoelectric signals, thereby providing more intuitive and dexterous prosthetic control. An important next consideration for these algorithms is if performance remains stable over multiple days. Here we introduce a new LSTM network and compare its performance to previously established state-of-the-art algorithms-a CNN and a modified Kalman filter (MKF)-in offline analyses using 76 days of intramuscular recordings from one amputee participant collected over 425 calendar days. Specifically, we assessed the robustness of each algorithm over time by training on data from the first (one, five, ten, 30, or 60) days and then testing on myoelectric signals on the last 16 days. Results indicate that training on additional datasets from prior days generally decreases the Root Mean Squared Error (RMSE) of intended and unintended movements for all algorithms. Across all algorithms trained with 60 days of data, the lowest RMSE for unintended movements was achieved with the LSTM. The LSTM also showed less across-day variance in RMSE of unintended movements relative to the other algorithms. Altogether this work suggests that the LSTM algorithm introduced here can provide more intuitive and dexterous control for prosthetic users, and that training on multiple days of data improves overall performance on subsequent days, at least for offline analyses.

Portable System for Home Use Enables Closed-Loop, Continuous Control of Multi-Degree-of-Freedom Bionic Arm.

Commercial prosthetic hands are frequently abandoned due to unintuitive control methods and a lack of sensory feedback from the prosthesis. Advanced neuromyoelectric prostheses can restore intuitive control and sensory feedback to prosthesis users and potentially reduce abandonment. However, not all advanced prosthetic systems are deployable for home use on portable systems with limited computational power. In this work, we use a commercially available portable neural interface processor (the Ripple Neuro Nomad), and a multi-degree-of-freedom bionic arm (the DEKA LUKE Arm) to create a closed-loop neuromyoelectric prosthesis. The system restores intuitive, independent, continuous control over the arm's six-degrees-of-freedom and provides sensory feedback for up to 288 neural and six vibrotactile channels. Additionally, the large storage capacity of the system enables high-resolution logging of EMG, hand positions, prosthesis sensors, and stimulation parameters. We developed two GUIs enabling wireless, real-time adjustments to motor control and feedback parameters: one with nearly full control over motor control and feedback parameters for investigators, and one with restricted capabilities enabling end-user safety. We verified the system's closed-loop function through a fragile egg task with vibrotactile sensory feedback. We tested the neural stimulation with an amplifier capable of eliciting transcutaneous percepts. This neuromyoelectric prosthetic system will be used for an extended take-home trial that could provide strong clinical justification for advanced, closed-loop prostheses.Clinical Relevance- This work establishes an advanced, intuitive, sensorized prosthesis that can be used in home and clinical settings.

Predictors of neurosurgical intervention in complicated mild traumatic brain injury patients: a retrospective cohort study.

OBJECTIVES: To determine the predicting demographic, clinical and radiological factors for neurosurgical intervention in complicated mild traumatic brain injury (mTBI) patients. METHODS: Design: retrospective multicenter cohort study. Participants: patients aged ≥16 presenting to all level-I trauma centers in Quebec between 09/2016 and 12/2017 with mTBI(GCS 13-15) and complication on initial head CT (intracranial hemorrhage/skull fracture). Procedure: Consecutive medical records were reviewed and separated into two groups: no neurosurgical intervention and neurosurgical intervention (NSI). Main outcome: neurosurgical intervention. Analysis: multiple logistic regression model. RESULTS: Four hundred and seventy-eight patients were included and 40 underwent NSI. One patient had radiological deterioration but no clinical deterioration prior to surgery. Subdural hemorrhage ≥4 mm width (OR:3.755 [95% CI:1.290-10.928]) and midline shift (OR:7.507 [95% CI: 3.317-16.989]) increased the risk of NSI. Subarachnoid hemorrhage was associated with a lower risk of NSI (OR:0.312 [95% CI: 0.136-0.713]). All other intracranial hemorrhages were not associated with NSI. CONCLUSION: Radiological deterioration was not associated with the incidence of NSI. Subdural hemorrhage and midline shift should be predicting factors for neurosurgery. Some patients with isolated findings such as subarachnoid hemorrhage could be safely managed in their original center without being transferred to a level-I trauma center.

Adverse Events Associated With Electrical Cardioversion in Patients With Acute Atrial Fibrillation and Atrial Flutter.

BACKGROUND: We sought to evaluate safety of electrical cardioversion (ECV) for patients with acute atrial fibrillation (AF) or atrial flutter (AFL) in the emergency department (ED). METHODS: This was an analysis of data from 4 multicentre AF/AFL studies conducted from 2008 to 2019 at 23 large EDs. We included adult patients who received attempts at ECV and who had presented acutely after symptom onset. Staff manually reviewed study and clinical records to abstract data. RESULTS: We evaluated 1736 ECV cases with a mean age of 60.1 years and 67.1% male. The overall success of ECV was 90.2% (95% confidence interval 88.7%-91.6%), with 4.9% of patients admitted. ED physicians performed the ECV in 95.2% and provided sedation in 96.5%; 13.9% (12.3%-15.7%) of cases experienced important adverse events that required treatment, and 0.4% were classified as life threatening. Another 5.6% had adverse events that did not require treatment. Logistic regression found that the RAFF-3 study cohort (odds ratio [OR] 2.0), age ≥ 85 years (OR 2.1), coronary artery disease (OR 1.5), midazolam (OR 1.9), and fentanyl (OR 1.5) were associated with important adverse events. CONCLUSIONS: This large evaluation of the safety of ECV for acute AF/AFL in the ED found that while serious adverse events were rare, there were a concerning number of events following sedation that required intervention. Physicians should be aware that older age, coronary artery disease, and fentanyl are associated with higher risks of important adverse events. This study provides more information for shared decision making discussions with patients when choosing between drug-shock and shock-only cardioversion strategies.

[What knows a frail swiss population about chronic obstructive pulmonary disease?] / Que sait une population suisse fragilisée de la bronchopneumopathie chronique obstructive ?

COPD affects nearly 400 000 people in Switzerland. It remains under-diagnosed and patients know little about it. This survey study aimed to measure this knowledge in a population receiving home care in the canton of Neuchâtel. Knowledge of the terms « COPD ¼ and « emphysema ¼ was not related to gender, the fact that patients had already had spirometry or the COPD risk group to which they belonged. Patients treated with inhaled drugs, smokers and ex-smokers were more familiar with the term « COPD ¼. The treatment of people with COPD requires careful monitoring of those diagnosed with the disease, but also increased attention to the disease itself and its symptoms among patients, caregivers and physicians.

La bronchopneumopathie chronique obstructive (BPCO) atteint près de 400 000 personnes en Suisse. Elle reste sous-diagnostiquée et les patients la connaissent peu. Cette étude sous forme d'enquête visait à mesurer ces connaissances dans une population qui reçoit des soins à domicile dans le canton de Neuchâtel. La connaissance des termes « BPCO ¼ et « emphysème ¼ n'avait pas de relation avec le sexe, le fait que les patients aient déjà eu une spirométrie ou le groupe de risque de BPCO auquel ils appartenaient. Les patients traités par médicaments inhalés, les fumeurs et les ex-fumeurs étaient plus familiers avec le terme « BPCO ¼. Le traitement des personnes atteintes de BPCO passe par un suivi attentif de celles chez qui on a diagnostiqué la maladie, mais aussi par une attention accrue à la maladie elle-même et à ses symptômes chez les patients, les soignants et les médecins.

Activities of daily living with bionic arm improved by combination training and latching filter in prosthesis control comparison.

BACKGROUND: Advanced prostheses can restore function and improve quality of life for individuals with amputations. Unfortunately, most commercial control strategies do not fully utilize the rich control information from residual nerves and musculature. Continuous decoders can provide more intuitive prosthesis control using multi-channel neural or electromyographic recordings. Three components influence continuous decoder performance: the data used to train the algorithm, the algorithm, and smoothing filters on the algorithm's output. Individual groups often focus on a single decoder, so very few studies compare different decoders using otherwise similar experimental conditions. METHODS: We completed a two-phase, head-to-head comparison of 12 continuous decoders using activities of daily living. In phase one, we compared two training types and a smoothing filter with three algorithms (modified Kalman filter, multi-layer perceptron, and convolutional neural network) in a clothespin relocation task. We compared training types that included only individual digit and wrist movements vs. combination movements (e.g., simultaneous grasp and wrist flexion). We also compared raw vs. nonlinearly smoothed algorithm outputs. In phase two, we compared the three algorithms in fragile egg, zipping, pouring, and folding tasks using the combination training and smoothing found beneficial in phase one. In both phases, we collected objective, performance-based (e.g., success rate), and subjective, user-focused (e.g., preference) measures. RESULTS: Phase one showed that combination training improved prosthesis control accuracy and speed, and that the nonlinear smoothing improved accuracy but generally reduced speed. Phase one importantly showed simultaneous movements were used in the task, and that the modified Kalman filter and multi-layer perceptron predicted more simultaneous movements than the convolutional neural network. In phase two, user-focused metrics favored the convolutional neural network and modified Kalman filter, whereas performance-based metrics were generally similar among all algorithms. CONCLUSIONS: These results confirm that state-of-the-art algorithms, whether linear or nonlinear in nature, functionally benefit from training on more complex data and from output smoothing. These studies will be used to select a decoder for a long-term take-home trial with implanted neuromyoelectric devices. Overall, clinical considerations may favor the mKF as it is similar in performance, faster to train, and computationally less expensive than neural networks.

Discriminability of multiple cutaneous and proprioceptive hand percepts evoked by intraneural stimulation with Utah slanted electrode arrays in human amputees.

BACKGROUND: Electrical stimulation of residual afferent nerve fibers can evoke sensations from a missing limb after amputation, and bionic arms endowed with artificial sensory feedback have been shown to confer functional and psychological benefits. Here we explore the extent to which artificial sensations can be discriminated based on location, quality, and intensity. METHODS: We implanted Utah Slanted Electrode Arrays (USEAs) in the arm nerves of three transradial amputees and delivered electrical stimulation via different electrodes and frequencies to produce sensations on the missing hand with various locations, qualities, and intensities. Participants performed blind discrimination trials to discriminate among these artificial sensations. RESULTS: Participants successfully discriminated cutaneous and proprioceptive sensations ranging in location, quality and intensity. Performance was significantly greater than chance for all discrimination tasks, including discrimination among up to ten different cutaneous location-intensity combinations (15/30 successes, p < 0.0001) and seven different proprioceptive location-intensity combinations (21/40 successes, p < 0.0001). Variations in the site of stimulation within the nerve, via electrode selection, enabled discrimination among up to five locations and qualities (35/35 successes, p < 0.0001). Variations in the stimulation frequency enabled discrimination among four different intensities at the same location (13/20 successes, p < 0.0005). One participant also discriminated among individual stimulation of two different USEA electrodes, simultaneous stimulation on both electrodes, and interleaved stimulation on both electrodes (20/24 successes, p < 0.0001). CONCLUSION: Electrode location, stimulation frequency, and stimulation pattern can be modulated to evoke functionally discriminable sensations with a range of locations, qualities, and intensities. This rich source of artificial sensory feedback may enhance functional performance and embodiment of bionic arms endowed with a sense of touch.