A position paper in support of face transplantation in the blind

Facially disfigured blind patients have historically been considered for face transplantation with skepticism. Although no formal position paper regarding their exclusion has been published to date, functional, social, rehabilitative, and ethical concerns related to blind patients' candidacy for face transplantation may be inferred. The authors provide a summary of these reservations and a counterargument to their assumptions, drawing on outcomes measures reported for face transplant procedures performed to date, and their own institutional experience in performing face transplants on blind patients. The authors therefore provide a rationale for the inclusion of facially disfigured blind patients in face transplantation protocols in the future.     

Design of a cybernetic hand for perception and action

Strong motivation for developing new prosthetic hand devices is provided by the fact that low functionality and controllability—in addition to poor cosmetic appearance—are the most important reasons why amputees do not regularly use their prosthetic hands. This paper presents the design of the CyberHand, a cybernetic anthropomorphic hand intended to provide amputees with functional hand replacement. Its design was bio-inspired in terms of its modular architecture, its physical appearance, kinematics, sensorization, and actuation, and its multilevel control system. Its underactuated mechanisms allow separate control of each digit as well as thumb–finger opposition and, accordingly, can generate a multitude of grasps. Its sensory system was designed to provide proprioceptive information as well as to emulate fundamental functional properties of human tactile mechanoreceptors of specific importance for grasp-and-hold tasks. The CyberHand control system presumes just a few efferent and afferent channels and was divided in two main layers: a high-level control that interprets the user’s intention (grasp selection and required force level) and can provide pertinent sensory feedback and a low-level control responsible for actuating specific grasps and applying the desired total force by taking advantage of the intelligent mechanics. The grasps made available by the high-level controller include those fundamental for activities of daily living: cylindrical, spherical, tridigital (tripod), and lateral grasps. The modular and flexible design of the CyberHand makes it suitable for incremental development of sensorization, interfacing, and control strategies and, as such, it will be a useful tool not only for clinical research but also for addressing neuroscientific hypotheses regarding sensorimotor control.     

Rubber hands feel touch, but not in blind individuals

Psychology and neuroscience have a long-standing tradition of studying blind individuals to investigate how visual experience shapes perception of the external world. Here, we study how blind people experience their own body by exposing them to a multisensory body illusion: the somatic rubber hand illusion. In this illusion, healthy blindfolded participants experience that they are touching their own right hand with their left index finger, when in fact they are touching a rubber hand with their left index finger while the experimenter touches their right hand in a synchronized manner (Ehrsson et al. 2005). We compared the strength of this illusion in a group of blind individuals (n = 10), all of whom had experienced severe visual impairment or complete blindness from birth, and a group of age-matched blindfolded sighted participants (n = 12). The illusion was quantified subjectively using questionnaires and behaviorally by asking participants to point to the felt location of the right hand. The results showed that the sighted participants experienced a strong illusion, whereas the blind participants experienced no illusion at all, a difference that was evident in both tests employed. A further experiment testing the participants' basic ability to localize the right hand in space without vision (proprioception) revealed no difference between the two groups. Taken together, these results suggest that blind individuals with impaired visual development have a more veridical percept of self-touch and a less flexible and dynamic representation of their own body in space compared to sighted individuals. We speculate that the multisensory brain systems that re-map somatosensory signals onto external reference frames are less developed in blind individuals and therefore do not allow efficient fusion of tactile and proprioceptive signals from the two upper limbs into a single illusory experience of self-touch as in sighted individuals.     

Surface EMG pattern recognition for real-time control of a wrist exoskeleton

Background  

Surface electromyography (sEMG) signals have been used in numerous studies for the classification of hand gestures and movements and successfully implemented in the position control of different prosthetic hands for amputees. sEMG could also potentially be used for controlling wearable devices which could assist persons with reduced muscle mass, such as those suffering from sarcopenia. While using sEMG for position control, estimation of the intended torque of the user could also provide sufficient information for an effective force control of the hand prosthesis or assistive device. This paper presents the use of pattern recognition to estimate the torque applied by a human wrist and its real-time implementation to control a novel two degree of freedom wrist exoskeleton prototype (WEP), which was specifically developed for this work.     

Surface EMG in advanced hand prosthetics

One of the major problems when dealing with highly dexterous, active hand prostheses is their control by the patient wearing them. With the advances in mechatronics, building prosthetic hands with multiple active degrees of freedom is realisable, but actively controlling the position and especially the exerted force of each finger cannot yet be done naturally. This paper deals with advanced robotic hand control via surface electromyography. Building upon recent results, we show that machine learning, together with a simple downsampling algorithm, can be effectively used to control on-line, in real time, finger position as well as finger force of a highly dexterous robotic hand. The system determines the type of grasp a human subject is willing to use, and the required amount of force involved, with a high degree of accuracy. This represents a remarkable improvement with respect to the state-of-the-art of feed-forward control of dexterous mechanical hands, and opens up a scenario in which amputees will be able to control hand prostheses in a much finer way than it has so far been possible. This work is partially supported by the project NEURObotics, FP6-IST-001917.     

High density electromyography data of normally limbed and transradial amputee subjects for multifunction prosthetic control

Pattern recognition based control of powered upper limb myoelectric prostheses offers a means of extracting more information from the available muscles than conventional methods. By identifying repeatable patterns of muscle activity across multiple muscle sites rather than relying on independent EMG signals it is possible to provide more natural, reliable control of myoelectric prostheses. The purposes of this study were to (1) determine if participants can perform distinctive muscle activation patterns associated with multiple wrist and hand movements reliably and (2) to show that high density EMG can be applied individually to determine the electrode location of a clinically acceptable number of electrodes (maximally eight) to classify multiple wrist and hand movements reliably in transradial amputees. Eight normally limbed subjects (five female, three male) and four transradial amputee subjects (two traumatic and congenital) subjects participated in this study, which examined the classification accuracies of a pattern recognition control system. It was found that tasks could be classified with high accuracy (85-98%) with normally limbed subjects (10-13 tasks) and with amputees (4-6) tasks. In healthy subjects, reducing the number of electrodes to eight did not affect accuracy significantly when those electrodes were optimally placed, but did reduce accuracy significantly when those electrodes were distributed evenly. In the amputee subjects, reducing the number of electrodes up to 4 did not affect classification accuracy or the number of tasks with high accuracy, independent of whether those remaining electrodes were evenly distributed or optimally placed. The findings in healthy subjects suggest that high density EMG testing is a useful tool to identify optimal electrode sites for pattern recognition control, but its use in amputees still has to be proven. Instead of just identifying the electrode sites where EMG activity is strong, clinicians will be able to choose the electrode sites that provide the most important information for classification.     

Vibrotactile Sensory Substitution Elicits Feeling of Ownership of an Alien Hand

Tactile feedback plays a key role in the attribution of a limb to the self and in the motor control of grasping and manipulation. However, due to technological limits, current prosthetic hands do not provide amputees with cutaneous touch feedback. Recent findings showed that amputees can be tricked into experiencing an alien rubber hand as part of their own body, by applying synchronous touches to the stump which is out of view, and to the rubber hand in full view. It was suggested that similar effects could be achieved by using a prosthesis with touch sensors that provides synchronous cutaneous feedback through an array of tactile stimulators on the stump. Such a prosthesis holds the potential to be easily incorporated within one’s body scheme, because it would reproduce the perceptual illusion in everyday usage. We propose to use sensory substitution – specifically vibrotactile – to address this issue, as current haptic technology is still too bulky and inefficient. In this basic study we addressed the fundamental question of whether visuo-tactile modality mismatch promotes self-attribution of a limb, and to what extent compared to a modality-matched paradigm, on normally-limbed subjects. We manipulated visuo-tactile stimulations, comprising combinations of modality matched, modality mismatched, synchronous and asynchronous stimulations, in a set of experiments fashioned after the Rubber Hand Illusion. Modality mismatched stimulation was provided using a keypad-controlled vibrotactile display. Results from three independent measures of embodiment (questionnaires, pointing tests and skin conductance responses) indicate that vibrotactile sensory substitution can be used to induce self-attribution of a rubber hand when synchronous but modality-conflicting visuo-tactile stimulation is delivered to the biological finger pads and to the equivalent rubber hand phalanges.     

Fine detection of grasp force and posture by amputees via surface electromyography

The state-of-the-art feed-forward control of active hand prostheses is rather poor. Even dexterous, multi-fingered commercial prostheses are controlled via surface electromyography (EMG) in a way that enforces a few fixed grasping postures, or a very basic estimate of force. Control is not natural, meaning that the amputee must learn to associate, e.g., wrist flexion and hand closing. Nevertheless, recent literature indicates that much more information can be gathered from plain, old surface EMG. To check this issue, we have performed an experiment in which three amputees train a Support Vector Machine (SVM) using five commercially available EMG electrodes while asked to perform various grasping postures and forces with their phantom limbs. In agreement with recent neurological studies on cortical plasticity, we show that amputees operated decades ago can still produce distinct and stable signals for each posture and force. The SVM classifies the posture up to a precision of 95% and approximates the force with an error of as little as 7% of the signal range, sample-by-sample at 25 Hz. These values are in line with results previously obtained by healthy subjects while feed-forward controlling a dexterous mechanical hand. We then conclude that our subjects could finely feed-forward control a dexterous prosthesis in both force and position, using standard EMG in a natural way, that is, using the phantom limb.     

A review of musculoskeletal adaptations in individuals following major lower-limb amputation

Structural musculoskeletal adaptations following amputation, such as bone mineral density (BMD) or muscle architecture, are often overlooked despite their established contributions to gait rehabilitation and the development of adverse secondary physical conditions. The purpose of this review is to provide a summary of the existing literature investigating musculoskeletal adaptations in individuals with major lower-limb amputations to inform clinical practice and provide directions for future research. Google Scholar, PubMed, and Scopus were searched for original peer-reviewed studies that included individuals with transtibial or transfemoral amputations. Summary data of twenty-seven articles indicated reduced BMD and increased muscle atrophy in amputees compared to controls, and in the amputated limb compared to intact and control limbs. Specifically, BMD was reduced in T-scores and Z-scores, femoral neck, and proximal tibia. Muscle atrophy was evidenced by decreased thigh cross-sectional area, decreased quadriceps thickness, and increased amounts of thigh fat. Overall, amputees have impaired musculoskeletal health. Future studies should include dysvascular etiologies to address their effects on musculoskeletal health and functional mobility. Moreover, clinicians can use these findings to screen increased risks of adverse sequelae such as fractures, osteopenia/porosis, and muscular atrophy, as well as target specific rehabilitation exercises to reduce these risks.     

Early vision impairs tactile perception in the blind

Researchers have known for more than a century that crossing the hands can impair both tactile perception and the execution of appropriate finger movements. Sighted people find it more difficult to judge the temporal order when two tactile stimuli, one applied to either hand, are presented and their hands are crossed over the midline as compared to when they adopt a more typical uncrossed-hands posture. It has been argued that because of the dominant role of vision in motor planning and execution, tactile stimuli are remapped into externally defined coordinates (predominantly determined by visual inputs) that takes longer to achieve when external and body-centered codes (determined primarily by somatosensory/proprioceptive inputs) are in conflict and that involves both multisensory parietal and visual cortex. Here, we show that the performance of late, but not of congenitally, blind people was impaired by crossing the hands. Moreover, we provide the first empirical evidence for superior temporal order judgments (TOJs) for tactile stimuli in the congenitally blind. These findings suggest a critical role of childhood vision in modulating the perception of touch that may arise from the emergence of specific crossmodal links during development.     

Perspectives on establishing a public cord blood inventory in South Africa

The South African population is highly diverse, both ethnically and genetically. This diversity is particularly true for the African ancestry and various mixed ancestry population groups. These groups are under-represented in national and international bone marrow and peripheral blood donor registries, making it challenging to identify HLA-matched and mismatched unrelated donors when patients from these groups require allogeneic hematopoietic stem and progenitor cell transplantation. In most high-income countries, banked cord blood (CB) units provide an attractive source of hematopoietic progenitor cells for genetically diverse populations. SA does not have a public CB inventory, leaving many patients without access to this important treatment modality. Haploidentical transplantation provides an alternative. In recent years, the use of post-transplant cyclophosphamide has significantly reduced the incidence of graft-versus-host disease after haploidentical transplantation and has improved transplantation outcomes. However, it is difficult to identify suitable haploidentical donors in SA because of family disruption and a high prevalence of HIV. Here the authors provide a brief historical overview of the ethnic and genetic diversity of the country and region. The authors provide a southern African perspective on HLA diversity, consider the allogeneic hematopoietic stem and progenitor cell transplantation landscape and explore the need to establish a public CB bank (CBB) in SA. The health policy and regulatory frameworks that will impact on a CBB in the country SA are also explored. Finally, the authors discuss several matters we believe require attention when considering the establishment of a sustainable public CBB in the South African context.     

Sound localization in intact and one-eared crickets

Summary Intact and one-eared crickets,Gryllus bimaculatus, were tested for phonotactic behavior in a closed-loop and an open-loop situation and for related physiological characteristics of an identified auditory neuron pair, the left and the right AN2.Intact animals that performed phonotaxis in the closed-loop condition showed intended turning tendencies in the open-loop condition that correlated with the directional characteristics of their AN2s (Figs. 1–3).Animals in which one foreleg had been amputated during postembryonic development (one-eared regenerates) were classified according to their phonotactic performance as tracking or unoriented animals. The ability of one-eared regenerates to track a sound source was closely correlated with the direction of turning tendencies in the open-loop behavior and to specific features of their AN2 pair (Figs. 4–6).Some animals with one foreleg amputated as adults (one-eared amputees) perform stable phonotactic walking. Their open-loop behavior, however, is different from that of the tracking one- eared regenerates (Fig. 7).One-eared amputees showed stable phonotactic walking when calling song was presented from above and the sound intensity was varied according to the actual walking angle of the animal. The only orientational cue under this condition is the difference of sound intensity at different walking directions (Figs. 8–11).Different mechanisms are discussed for sound localization in one-eared regenerates and one- eared amputees based on turning tendencies which depend on the instantaneous stimulus intensity or on the intensity change between successive stimuli.     

Leg stiffness in unilateral transfemoral amputees across a range of running speeds

Carbon fiber running-specific prostheses have allowed lower extremity amputees to participate in running activity by providing spring-like properties in their affected limb. It has been established that as running speed increases, stiffness of the leg spring (leg stiffness; k_leg) remains constant in non-amputees. Although a better understanding of k_leg regulation may be helpful for the development of spring-based prostheses, little is known about stiffness regulation in unilateral transfemoral amputees. The aim of this study was to investigate stiffness regulation at different running speeds in unilateral transfemoral amputees wearing a running-specific prosthesis. Nine unilateral transfemoral amputees performed running on an instrumented treadmill across a range of speeds (30, 40, 50, 60, and 70% of their maximum running speed). Using a spring-mass model, k_leg was calculated as the ratio of maximal vertical ground reaction force to maximum leg compression during the stance phase in both affected and unaffected limbs. We found a decrease in k_leg from the slower speed to 70% speed for the affected limb, whereas no change was present in the unaffected limb. Specifically, there was a significant differences in the k_leg between 30% and 70%, 40% and 70%, and 50% and 70%, and the magnitude of the k_leg difference between affected and unaffected limbs varied with variations in running speeds in unilateral TFAs with an RSP. These results suggest the k_leg regulation strategy of unilateral transfemoral amputees is not the same in the affected and unaffected limbs across a range of running speeds.     

Adipose‐derived stem cell spheroids are superior to single‐cell suspensions to improve fat autograft long‐term survival

Autologous fat transplantation is a widely used procedure for surgical reconstruction of tissues. The resorption rate of this transplantation remains high and unpredictable, reinforcing the need of adjuvant treatments that increase the long‐term stability of grafts. Adipose‐derived stem cells (ASC) introduced as single cells in fat has been shown clinically to reduce the resorption of fat grafts. On the other hand, the formulation of ASC into cell spheroids results in the enhancement of their regenerative potential. In this study, we developed a novel method to produce highly homogeneous ASC spheroids and characterized their features and efficacy on fat transplantation. Spheroids conserved ASC markers and multipotency. A regenerative gene expression profile was maintained, and genes linked to autophagy were upregulated whereas proliferation was decreased. Their secreted proteome was enriched in comparison with single‐cell ASC suspension. Addition of spheroids to fat graft in an animal model of transplantation resulted in a better graft long‐term stability when compared to single ASC suspension. In conclusion, we provide a novel method to manufacture homogenous ASC spheroids. These ASC spheroids are superior to ASC in single‐cell suspension to improve the stability of fat transplants, reinforcing their potential in reconstructive surgery.     

Minimizing impairment in laborers with finger losses distal to the proximal interphalangeal joint by second toe transfer

Traditionally, toe-to-hand transfers have been reserved for thumb amputations or for use after severe mutilating injuries. The authors report their experience with the use of second toe-for-finger amputations with preserved or reconstructible proximal interphalangeal joints in manual workers. The aim of the procedure was to reduce impairment and to upgrade the hand from a functional and cosmetic standpoint. Fifteen second-toe wrap-around or variations were carried out on 11 adults (18 to 41 years old). Four patients with two or more finger amputations received two sequential second toes; four patients with two finger amputations received one toe; and each of three patients with single-digit amputation received a single toe. All but one amputation were performed less than 3 weeks after the accident. All toes survived. Range of motion at the native proximal interphalangeal joint was more than 90 percent in all patients but one; however, it was minimal at the transplanted joints. Patient satisfaction was high from a cosmetic and functional standpoint. Ten of 11 laborers resumed their previous activity. On the basis of this experience, a classification with aesthetic and functional implications is proposed to help in the decision-making process when dealing with multidigital injuries. It is concluded that second-toe transfer is an excellent choice for finger amputation distal to the proximal interphalangeal joint in laborers. Its prime indication is for amputations of two fingers where at least one toe should be transferred, as required, to achieve an "acceptable hand" (three-fingered hand). Early transfer allows salvage of critical structures from the damaged finger, such as joints, tendons, and bone, that otherwise would be lost. Early transplantation is highly recommended.     

Studies of Aquatic Fungi. XXVI. Hyphomycetes in the River Supraśi in Various Seasons of the Year with Reference to Environmental Conditions

The authors investigated the aquatic mycoflora and the environmental factors at two sites of the River Supraśl on the occurrence of various aquatic Hyphomycetes. At the stations investigated the presence of 56 aquatic Hyphomycetes species was noted. The foam of both site I and site II contained more species than did the water collected at these sites. Most of the aquatic Hyphomycetes found at the sites studied are common fungi quite frequently found in different kinds of water bodies. On the other hand 17 species have been comparatively seldom encountered up to date.     

Circadian genes in a blind subterranean mammal III: molecular cloning and circadian regulation of cryptochrome genes in the blind subterranean mole rat, Spalax ehrenbergi superspecies

The blind subterranean mole rat superspecies Spalax ehrenbergi is an extreme example of mammalian adaptation to life underground. Though this rodent is totally visually blind, harboring a drastically degenerated subcutaneous rudimentary eye, its daily activity rhythm is entrainable to LD cycles. This indicates that it confers light information to the clock, as has been previously shown by the authors in behavioral studies as well as by molecular analyses of its Clock/MOP3 and its three Per genes. The Cryptochrome (Cry) genes found in animals and plants act both as photoreceptors and as essential components of the negative feedback mechanism of the biological clock. To further understand the circadian system of this unique mammal, the authors cloned and characterized the open reading frame of Spalax Cry1 and Cry2. The Spalax CRY1 protein is significantly closer to the human homolog than to the mice one, in contrast to the evolutionary expectations. They have found two isoforms of Cry2 in Spalax, which differ in their 5' end of the open reading frame and defined their expression in Spalax populations. They found a large and significant excess of heterozygotes of sCry2 (sCry2L/S genotype). Both sCry1 and sCry2 mRNAs were found in the SCN, the eye, the harderian gland, as well as in a wide range of peripheral tissues. Their expression pattern under different LD conditions has also been analyzed. As was already shown for other circadian genes, despite being blind and living in darkness, the Cry genes of Spalax behave in a similar, though not identical, pattern as in sighted animals. Once again, the results indicate that the uniquely hypertrophied harderian gland of Spalax plays a key role in its circadian system.     

Design and technical construction of a tactile display for sensory feedback in a hand prosthesis system

Background  

The users of today's commercial prosthetic hands are not given any conscious sensory feedback. To overcome this deficiency in prosthetic hands we have recently proposed a sensory feedback system utilising a "tactile display" on the remaining amputation residual limb acting as man-machine interface. Our system uses the recorded pressure in a hand prosthesis and feeds back this pressure onto the forearm skin. Here we describe the design and technical solution of the sensory feedback system aimed at hand prostheses for trans-radial/humeral amputees. Critical parameters for the sensory feedback system were investigated.     

A Haptic Feedback Scheme to Accurately Position a Virtual Wrist Prosthesis Using a Three-Node Tactor Array

In this paper, a novel haptic feedback scheme, used for accurately positioning a 1DOF virtual wrist prosthesis through sensory substitution, is presented. The scheme employs a three-node tactor array and discretely and selectively modulates the stimulation frequency of each tactor to relay 11 discrete haptic stimuli to the user. Able-bodied participants were able to move the virtual wrist prosthesis via a surface electromyography based controller. The participants evaluated the feedback scheme without visual or audio feedback and relied solely on the haptic feedback alone to correctly position the hand. The scheme was evaluated through both normal (perpendicular) and shear (lateral) stimulations applied on the forearm. Normal stimulations were applied through a prototype device previously developed by the authors while shear stimulations were generated using an ubiquitous coin motor vibrotactor. Trials with no feedback served as a baseline to compare results within the study and to the literature. The results indicated that using normal and shear stimulations resulted in accurately positioning the virtual wrist, but were not significantly different. Using haptic feedback was substantially better than no feedback. The results found in this study are significant since the feedback scheme allows for using relatively few tactors to relay rich haptic information to the user and can be learned easily despite a relatively short amount of training. Additionally, the results are important for the haptic community since they contradict the common conception in the literature that normal stimulation is inferior to shear. From an ergonomic perspective normal stimulation has the potential to benefit upper limb amputees since it can operate at lower frequencies than shear-based vibrotactors while also generating less noise. Through further tuning of the novel haptic feedback scheme and normal stimulation device, a compact and comfortable sensory substitution device for upper limb amputees might be created.