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Background: Compliance with the recommended 30 s drying time of alcohol-based hand rub (ABHR) is often suboptimal. To increase hand hygiene compliance at a neonatal intensive care unit (NICU), we installed an Incubator Traffic Light (ITL) system which shows ‘green light’ to open incubator doors after the recommended drying time. Aim: To measure the impact of this visual feedback system on NICU healthcare professionals' compliance with the recommended ABHR drying time. Methods: Ten traffic light systems were installed on incubators at a NICU, five of which provided visual feedback, and five, serving as a control group, did not provide visual feedback. During a two-month period, the systems measured drying time between the moment of dispensing ABHR and opening the incubator's doors. The drying times of the incubators were compared with and without feedback. Findings: Of the 6422 recorded hand hygiene events, 658 were valid for data analysis. Compliance with correct drying time reached 75% (N = 397/526) for incubators equipped with visual feedback versus 36% (N = 48/132; P < 0.0001) for incubators lacking this feature. Conclusion: The ITL improves compliance with the recommended 30 s ABHR drying time in a NICU setting., Medical Instruments & Bio-Inspired Technology

Our hands and arms are incredibly dexterous and capable appendages. Controlling our upper limbs requires the integration of complex descending motor control signals with rich streams of sensory information returned from the limb. Advanced bionic prostheses are rapidly advancing, however the ability to intuitively control the device and receive sensory information remains a challenge. In response to these current barriers to intuitive control and feedback, nerve-machine interfaces have emerged that can decode a user’s motor intent directly from the human nervous system. However, many of these nerve-machine interfaces are experimental and may involve surgically implanted hardware, thus making this solution inaccessible to many. Currently at UC Davis Health, many individuals with upper limb loss have been receiving targeted muscle reinnervation for the prevention of phantom and neuroma pain (N-TMR). As there is a need for pain management, N-TMR is a rapidly emerging clinical treatment for pain management done at the time of amputation. In this work, we demonstrate that N-TMR not only offers prophylactic benefits but also provides opportunities for intuitive prosthetic control and feedback. Although N-TMR is more widely accessible, it faces many challenges with current advanced prostheses. With N-TMR, there is no consideration for the depth of the muscle being reinnervated nor electrical crosstalk which can impact surface measurement techniques used for prosthetic control such as surface electromyography. In this thesis work, we examined a novel control technique and sensory feedback method to address these challenges by employing ultrasound and machine learning approaches. Sonomyography (SMG) is an ultrasound imaging technique that applies image processing and pattern recognition algorithms to detect user’s intentions from muscle deformations when a missing hand movement is attempted. We found that four participants with N-TMR surgery could enact 4-10 hand grasps with

The somatotopic interface (SI) and non-somatotopic interface (NI) are commonly used to provide non-invasive sensory feedback. Nevertheless, differences between somatotopic and non-somatotopic feedbacks are rarely reported, and objective evaluations of the corresponding brain response are missing as well. Few studies have reported how to design the stimulation encoding strategy based on the two interfaces in sensory feedback. The objective of this study was to investigate the difference in sensory characteristics between SI and NI, and propose an optimal encoding method for non-invasive feedback interfaces.. We recruited seven amputees and compared the tactile sensitivity to stimulated positions and intensities between SI (phantom finger area) and NI (upper arm) in a tactile discrimination task. Electroencephalography (EEG) evaluation task was subsequently conducted to objectively evaluate the stimulus-evoked brain response for SI and NI. Finally, the two kinds of tactile information (stimulated position and intensity) was applied to an object recognition task in a closed-loop prosthesis control system. Specifically, the object size was reflected by the prosthetic finger position through stimulated position encoding, and the object stiffness was reflected by the contact force of prosthetic fingers through stimulated intensity encoding. We compared the performance under four feedback conditions (combinations between two kinds of tactile information and two interfaces).. Behavioral results showed that NI was more sensitive to position information while SI was more sensitive to intensity information. EEG results were consistent with behavioral results, showing a higher sensitivity of sensory alpha ERD and a stronger correlation between alpha ERD and discrimination accuracies for NI in the position discrimination, while the trend was opposite in the intensity discrimination. The feedback encoding allowed amputees to discriminate the size and stiffness of nine objects w

Many hexapods and other robots struggle with walking in uneven terrain, this is due to their lack of sensory feedback. This is the problem aimed to be solved by introducing a sensory feedback loop that measures the current over the servos. By doing this one could know whether or not the leg is in contact with the ground. If a successful sensor can be made, this method could be implemented on any hexapod that uses servos and inverse kinematics for their locomotion to enable them to walk in uneven terrain. With the complete system in place most of what was expected from the system was achieved. HEXA can indeed walk in uneven terrain where the terrain had the maximum height difference of ±2.3 cm, as seen in the video linked in appendix B. It also can detect when a leg has contact with the ground but due to low servo quality the walking could not be tested to its full extent., Många hexapoder och andra robotar har svårigheter att gå i ojämn terräng, detta är på grund av hur de inte har någon form av senosoråterkoppling. Detta är problemet som siktas på att lösas genom att introducera en sensor återkopplings slinga som mäter stömmen över de olika servon. Genom att implementera detta kan en få reda på om benet har kontakt med marken eller ej. Om en lyckas senor kan skapas, skulle denna metod kunna implementeras till vilken annan hexapodal robot som använder sig av servos och inverse kinematik för sin framdriving. Med det kompletta systemet integrerat uppfylls nästan allt som var förväntad. HEXA kan gå i en ojämn terräng med den maximala höjdsillnaden av ±2.3 cm, som sett i videon i appendix B. Samt kan den märka av när ett av benen är i marken, men på grund av den låga servokvaliteten kunde inte gången testas till sin fulla förmåga.

Many hexapods and other robots struggle with walking in uneven terrain, this is due to their lack of sensory feedback. This is the problem aimed to be solved by introducing a sensory feedback loop that measures the current over the servos. By doing this one could know whether or not the leg is in contact with the ground. If a successful sensor can be made, this method could be implemented on any hexapod that uses servos and inverse kinematics for their locomotion to enable them to walk in uneven terrain. With the complete system in place most of what was expected from the system was achieved. HEXA can indeed walk in uneven terrain where the terrain had the maximum height difference of ±2.3 cm, as seen in the video linked in appendix B. It also can detect when a leg has contact with the ground but due to low servo quality the walking could not be tested to its full extent., Många hexapoder och andra robotar har svårigheter att gå i ojämn terräng, detta är på grund av hur de inte har någon form av senosoråterkoppling. Detta är problemet som siktas på att lösas genom att introducera en sensor återkopplings slinga som mäter stömmen över de olika servon. Genom att implementera detta kan en få reda på om benet har kontakt med marken eller ej. Om en lyckas senor kan skapas, skulle denna metod kunna implementeras till vilken annan hexapodal robot som använder sig av servos och inverse kinematik för sin framdriving. Med det kompletta systemet integrerat uppfylls nästan allt som var förväntad. HEXA kan gå i en ojämn terräng med den maximala höjdsillnaden av ±2.3 cm, som sett i videon i appendix B. Samt kan den märka av när ett av benen är i marken, men på grund av den låga servokvaliteten kunde inte gången testas till sin fulla förmåga.

Fish perform rapid escape responses to avoid sudden predatory attacks. During escape responses, fish bend their bodies into a C-shape and quickly turn away from the predator and accelerate. The escape trajectory is determined by the initial turn (stage 1) and a contralateral bend (stage 2). Previous studies have used a single threat or model predator as a stimulus. In nature, however, multiple predators may attack from different directions simultaneously or in close succession. It is unknown whether fish are able to change the course of their escape response when startled by multiple stimuli at various time intervals. Pacific staghorn sculpin (Leptocottus armatus) were startled with a left and right visual stimulus in close succession. By varying the timing of the second stimulus, we were able to determine when and how a second stimulus could affect the escape response direction. Four treatments were used: a single visual stimulus (control); or two stimuli coming from opposite sides separated by a 0 ms (simultaneous treatment), 33 ms or 83 ms time interval. The 33 ms and 83 ms time intervals were chosen to occur either side of a predicted 60 ms visual escape latency (i.e. during stage 1). The 0 ms and 33 ms treatments influenced both the escape trajectory and the stage 1 turning angle, compared with a single stimulation, whereas the 83 ms treatment had no effect on the escape trajectory. We conclude that Pacific staghorn sculpin can modulate their escape trajectory only between stimulation and the onset of the response, but the escape trajectory cannot be modulated after the body motion has started., Journal of Experimental Biology, 225(9), art. no. jeb243328; 2022

Fish perform rapid escape responses to avoid sudden predatory attacks. During escape responses, fish bend their bodies into a C-shape and quickly turn away from the predator and accelerate. The escape trajectory is determined by the initial turn (stage 1) and a contralateral bend (stage 2). Previous studies have used a single threat or model predator as a stimulus. In nature, however, multiple predators may attack from different directions simultaneously or in close succession. It is unknown whether fish are able to change the course of their escape response when startled by multiple stimuli at various time intervals. Pacific staghorn sculpin (Leptocottus armatus) were startled with a left and right visual stimulus in close succession. By varying the timing of the second stimulus, we were able to determine when and how a second stimulus could affect the escape response direction. Four treatments were used: a single visual stimulus (control); or two stimuli coming from opposite sides separated by a 0 ms (simultaneous treatment), 33 ms or 83 ms time interval. The 33 ms and 83 ms time intervals were chosen to occur either side of a predicted 60 ms visual escape latency (i.e. during stage 1). The 0 ms and 33 ms treatments influenced both the escape trajectory and the stage 1 turning angle, compared with a single stimulation, whereas the 83 ms treatment had no effect on the escape trajectory. We conclude that Pacific staghorn sculpin can modulate their escape trajectory only between stimulation and the onset of the response, but the escape trajectory cannot be modulated after the body motion has started., Journal of Experimental Biology, 225(9), art. no. jeb243328; 2022

Sensory feedback through spinal interneurons contributes to plantar flexor muscle activity during walking, but it is unknown whether this is also the case during nonlocomotor movements. Here, we explored the effect of temporary reduction of sensory feedback to ankle plantar flexors during voluntary contraction in sitting subjects. Thirteen healthy adults (mean age 32 yr) were seated with the right leg attached to a foot plate which could be moved in dorsi- or plantarflexion direction by a computer-controlled motor. EMG was recorded from the tibialis anterior (TA) and soleus (Sol) muscles. During static plantar flexion, while the plantar flexors were slowly stretched, a sudden plantar flexion caused a decline in Sol EMG at the same latency as the stretch reflex. This decline in EMG activity was still observed when transmission from dorsiflexors was blocked. It disappeared when transmission from ankle plantar flexors was also blocked. The same quick plantarflexion failed to produce a decline in EMG activity at the latency of the stretch reflex in the absence of slow stretch of the plantar flexors. Instead, a decline in EMG activity was observed 15-20 ms later. This decline disappeared following block of transmission from antagonists, suggesting that reciprocal inhibition was involved. These findings show that unload of ankle plantar flexors does not cause a similar drop in Sol EMG during voluntary contraction as during walking. This implies that sensory feedback through spinal interneurons only contributes little to the neural drive to plantar flexor muscles during human voluntary contraction in sitting subjects.NEW & NOTEWORTHY Sensory feedback through spinal reflex pathways makes only a minor contribution to neural drive to muscles during voluntary ankle plantar flexion. This differs distinctly from observations during walking and suggests that the neural drive to ankle plantar flexors during voluntary contraction do not rely on sensory feedback through simil

Fish perform rapid escape responses to avoid sudden predatory attacks. During escape responses, fish bend their bodies into a C-shape and quickly turn away from the predator and accelerate. The escape trajectory is determined by the initial turn (Stage 1) and a contralateral bend (Stage 2). Previous studies have used a single threat or model predator as a stimulus. In nature, however, multiple predators may attack from different directions simultaneously or in close succession. It is unknown whether fish are able to change the course of their escape response when startled by multiple stimuli at various time intervals. Pacific staghorn sculpin (Leptocottus armatus) were startled with a left and right visual stimulus in close succession. By varying the timing of the second stimulus, we were able to determine when and how a second stimulus could affect the escape response direction. Four treatments were used: a single visual stimulus (control); or two stimuli coming from opposite sides separated by a 0 ms (simultaneous treatment); a 33 ms; or a 83 ms time interval. The 33 ms and 83 ms time intervals were chosen to occur shortly before and after a predicted 60 ms visual escape latency (i.e. during Stage 1). The 0 ms and 33 ms treatments influenced both the escape trajectory and the Stage 1 turning angle, compared to a single stimulation, whereas the 83 ms treatment had no effect on the escape trajectory. We conclude that Pacific staghorn sculpin can modulate their escape trajectory only between stimulation and the onset of the response, but that escape trajectory cannot be modulated after the body motion has started.

Hand amputation results in the loss of motor and sensory functions, impacting activities of daily life and quality of life. Commercially available prosthetic hands restore the motor function but lack sensory feedback, which is crucial to receive information about the prosthesis state in real-time when interacting with the external environment. As a supplement to the missing sensory feedback, the amputee needs to rely on visual and audio cues to operate the prosthetic hand, which can be mentally demanding. This thesis revolves around finding potential solutions to contribute to an intuitive non-invasive sensory feedback system that could be cognitively less burdensome and enhance the sense of embodiment (the feeling that an artificial limb belongs to one’s own body), increasing acceptance of wearing a prosthesis.A sensory feedback system contains sensors to detect signals applied to the prosthetics. The signals are encoded via signal processing to resemble the detected sensation delivered by actuators on the skin. There is a challenge in implementing commercial sensors in a prosthetic finger. Due to the prosthetic finger’s curvature and the fact that some prosthetic hands use a covering rubber glove, the sensor response would be inaccurate. This thesis shows that a pneumatic touch sensor integrated into a rubber glove eliminates these errors. This sensor provides a consistent reading independent of the incident angle of stimulus, has a sensitivity of 0.82 kPa/N, a hysteresis error of 2.39±0.17%, and a linearity error of 2.95±0.40%.For intuitive tactile stimulation, it has been suggested that the feedback stimulus should be modality-matched with the intention to provide a sensation that can be easily associated with the real touch on the prosthetic hand, e.g., pressure on the prosthetic finger should provide pressure on the residual limb. A stimulus should also be spatially matched (e.g., position, size, and shape). Electrotactile stimulation has the ability to provid

Reinforcement-learning (RL)-based brain-machine interfaces (BMIs) interpret dynamic neural activity into movement intention without patients’ real limb movements, which is promising for clinical applications. A movement task generally requires the subjects to reach the target within one step and rewards the subjects instantaneously. However, a real BMI scenario involves tasks that require multiple steps, during which sensory feedback is provided to indicate the status of the prosthesis, and the reward is only given at the end of the trial. Actually, subjects internally evaluate the sensory feedback to adjust motor activity. Existing RL-BMI tasks have not fully utilized the internal evaluation from the brain upon the sensory feedback to guide the decoder training, and there lacks an effective tool to assign credit for the multi-step decoding task. We propose first to extract intermediate guidance from the medial prefrontal cortex (mPFC) to assist the learning of multi-step decoding in an RL framework. To effectively explore the neural-action mapping in a large state-action space, a temporal difference (TD) method is incorporated into quantized attention-gated kernel reinforcement learning (QAGKRL) to assign the credit over the temporal sequence of movement, but also discriminate spatially in the Reproducing Kernel Hilbert Space (RKHS). We test our approach on the data collected from the primary motor cortex (M1) and the mPFC of rats when they brain control the cursor to reach the target within multiple steps. Compared with the models which only utilize the final reward, the intermediate evaluation interpreted from the mPFC can help improve the prediction accuracy by 10.9% on average across subjects, with faster convergence and more stability. Moreover, our proposed algorithm further increases 18.2% decoding accuracy compared with existing TD-RL methods. The results reveal the possibility of achieving better multi-step decoding performance for more complicated

Sensory feedback through spinal interneurons contributes to plantar flexor muscle activity during walking, but it is unknown whether this is also the case during nonlocomotor movements. Here, we explored the effect of temporary reduction of sensory feedback to ankle plantar flexors during voluntary contraction in sitting subjects. Thirteen healthy adults (mean age 32 yr) were seated with the right leg attached to a foot plate which could be moved in dorsi- or plantarflexion direction by a computer-controlled motor. EMG was recorded from the tibialis anterior (TA) and soleus (Sol) muscles. During static plantar flexion, while the plantar flexors were slowly stretched, a sudden plantar flexion caused a decline in Sol EMG at the same latency as the stretch reflex. This decline in EMG activity was still observed when transmission from dorsiflexors was blocked. It disappeared when transmission from ankle plantar flexors was also blocked. The same quick plantarflexion failed to produce a decline in EMG activity at the latency of the stretch reflex in the absence of slow stretch of the plantar flexors. Instead, a decline in EMG activity was observed 15-20 ms later. This decline disappeared following block of transmission from antagonists, suggesting that reciprocal inhibition was involved. These findings show that unload of ankle plantar flexors does not cause a similar drop in Sol EMG during voluntary contraction as during walking. This implies that sensory feedback through spinal interneurons only contributes little to the neural drive to plantar flexor muscles during human voluntary contraction in sitting subjects.NEW & NOTEWORTHY Sensory feedback through spinal reflex pathways makes only a minor contribution to neural drive to muscles during voluntary ankle plantar flexion. This differs distinctly from observations during walking and suggests that the neural drive to ankle plantar flexors during voluntary contraction do not rely on sensory feedback through simil

Author Posting. © Company of Biologists, 2021. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 224(7), (2021): jeb.240143, https://doi.org/10.1242/jeb.240143., Movement induces sensory stimulation of an animal's own sensory receptors, termed reafference. With a few exceptions, notably vestibular and proprioception, this reafference is unwanted sensory noise and must be selectively filtered in order to detect relevant external sensory signals. In the cerebellum-like electrosensory nucleus of elasmobranch fish, an adaptive filter preserves novel signals by generating cancellation signals that suppress predictable reafference. A parallel fiber network supplies the principal Purkinje-like neurons (called ascending efferent neurons, AENs) with behavior-associated internal reference signals, including motor corollary discharge and sensory feedback, from which predictive cancellation signals are formed. How distinct behavior-specific cancellation signals interact within AENs when multiple behaviors co-occur and produce complex, changing patterns of reafference is unknown. Here, we show that when multiple streams of internal reference signals are available, cancellation signals form that are specific to parallel fiber inputs temporally correlated with, and therefore predictive of, sensory reafference. A single AEN has the capacity to form more than one cancellation signal, and AENs form multiple cancellation signals simultaneously and modify them independently during co-occurring behaviors. Cancellation signals update incrementally during continuous behaviors, as well as episodic bouts of behavior that last minutes to hours. Finally, individual AENs, independently of their neighbors, form unique AEN-specific cancellation signals that depend on the particular sensory reafferent input it receives. Together, these results demonstrate the capacity of the adaptive filter to utilize multiple cancellation signals to suppress dynamic patterns of reafference arising from complex co-occurring and intermittently performed behaviors., This work was supported by National Science Foundation (NSF) and Wesleyan University grants to D.B. N.Y.L. was supported by Wesleyan University grants, a Freeman Asian Scholarship, and a Howard Hughes Medical Institute award for undergraduate summer research., 2022-04-15

Author Posting. © Company of Biologists, 2021. This article is posted here by permission of Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Experimental Biology 224(7), (2021): jeb.240143, https://doi.org/10.1242/jeb.240143., Movement induces sensory stimulation of an animal's own sensory receptors, termed reafference. With a few exceptions, notably vestibular and proprioception, this reafference is unwanted sensory noise and must be selectively filtered in order to detect relevant external sensory signals. In the cerebellum-like electrosensory nucleus of elasmobranch fish, an adaptive filter preserves novel signals by generating cancellation signals that suppress predictable reafference. A parallel fiber network supplies the principal Purkinje-like neurons (called ascending efferent neurons, AENs) with behavior-associated internal reference signals, including motor corollary discharge and sensory feedback, from which predictive cancellation signals are formed. How distinct behavior-specific cancellation signals interact within AENs when multiple behaviors co-occur and produce complex, changing patterns of reafference is unknown. Here, we show that when multiple streams of internal reference signals are available, cancellation signals form that are specific to parallel fiber inputs temporally correlated with, and therefore predictive of, sensory reafference. A single AEN has the capacity to form more than one cancellation signal, and AENs form multiple cancellation signals simultaneously and modify them independently during co-occurring behaviors. Cancellation signals update incrementally during continuous behaviors, as well as episodic bouts of behavior that last minutes to hours. Finally, individual AENs, independently of their neighbors, form unique AEN-specific cancellation signals that depend on the particular sensory reafferent input it receives. Together, these results demonstrate the capacity of the adaptive filter to utilize multiple cancellation signals to suppress dynamic patterns of reafference arising from complex co-occurring and intermittently performed behaviors., This work was supported by National Science Foundation (NSF) and Wesleyan University grants to D.B. N.Y.L. was supported by Wesleyan University grants, a Freeman Asian Scholarship, and a Howard Hughes Medical Institute award for undergraduate summer research., 2022-04-15

Electrical stimulation of peripheral afferents has been used to study the sensory neural code and restore lost sensory function after amputation. Recently, implantable neural interfaces have prompted multiple breakthroughs in artificial somatosensory feedback for individuals with amputation, resulting in functional and psychological benefits. Although promising, the invasive nature of these approaches limits wide clinical applications, hindering the development of advanced neuromodulation strategies for intuitive sensory feedback. Transcutaneous (surface) stimulation is a potential non-invasive alternative. However, traditional surface stimulation methods are hampered by inadequate electrode and stimulation parameter fitting, localized discomfort, poor selectivity, and limited percept modulation. An enhanced surface electrical neurostimulation platform has been developed to address the need for a non-invasive approach capable of selectively eliciting comfortable tactile percepts with a wide range of intensities, that could be used to complete functional tasks. Several strategies were developed and implemented within the platform to achieve these features. First, a novel channel-hopping interleaved pulse scheduling strategy was developed to elicit enhanced tactile percepts while avoiding the discomfort associated with localized charge densities. This strategy was evaluated with able-bodied human subjects and compared with traditional methods. Second, a bio-inspired charge-rate encoding strategy was implemented to enhance the range and gradation of evoked percept intensities. The encoding strategy was evaluated during psychophysical studies with surface stimulation in able-bodied subjects and intrafascicular stimulation in an individual with a transradial amputation. Finally, a series of functional studies with able-bodied subjects evaluated the functional benefits afforded by the enhanced feedback on their ability to determine the size and hardness of virtual objects

Amputation of a hand is a life-changing event, and the loss of motor and sensory functions leads to disability and has devastating effects on the individual. What is normally performed using two hands must be solved with only one, and the loss also affects body balance and body posture. In addition, amputation of a hand has psychological effects, and has an influence on social life, participation, and identity. A hand prosthesis has an important role in reducing the negative effects of an amputation. However, rejection of the prosthesis is common, due to expectations that are too high to be fulfilled and limitations in technical solutions, with possible overuse of the existing hand as a consequence. The overall aim of this work has been to further develop and implement a non-invasive concept for sensory feedback in hand prostheses. Specific aims were to explore forearm amputees’ views of prosthesis use and perception of sensory feedback, to investigate the sensory qualities of phantom hand maps (PHMs) in amputees, to determine whether it is possible to learn to associate sensory stimuli on the skin of the forearm to specific fingers in healthy non-amputee volunteers, and lastly to evaluate a non-invasive sensory feedback system for a prosthetic hand in the everyday lives of forearm amputees.Initial findings indicated that today’s myoelectric hand prostheses allow the wearer to experience agency―the experience of controlling one’s own motor acts―but the lack of sensory feedback appears to limit achievement of a sense of body ownership of the prosthesis. A PHM on the residual limb is a phenomenon seen in many amputees, and when it is touched it generates a perception of touch on the hand that no longer exists. The neurobiological basis of the phenomenon is not fully understood, but it probably originates from plastic changes within the brain following amputation and also changes in peripheral nerves. We have demonstrated that the PHM has better discriminative sensibil

It is widely accepted that unexpected sensory consequences of self-action engage the cerebellum. However, we currently lack consensus on where in the cerebellum, we find fine-grained differentiation to unexpected sensory feedback. This may result from methodological diversity in task-based human neuroimaging studies that experimentally alter the quality of self-generated sensory feedback. We gathered existing studies that manipulated sensory feedback using a variety of methodological approaches and performed activation likelihood estimation (ALE) meta-analyses. Only half of these studies reported cerebellar activation with considerable variation in spatial location. Consequently, ALE analyses did not reveal significantly increased likelihood of activation in the cerebellum despite the broad scientific consensus of the cerebellum's involvement. In light of the high degree of methodological variability in published studies, we tested for statistical dependence between methodological factors that varied across the published studies. Experiments that elicited an adaptive response to continuously altered sensory feedback more frequently reported activation in the cerebellum than those experiments that did not induce adaptation. These findings may explain the surprisingly low rate of significant cerebellar activation across brain imaging studies investigating unexpected sensory feedback. Furthermore, limitations of functional magnetic resonance imaging to probe the cerebellum could play a role as climbing fiber activity associated with feedback error processing may not be captured by it. We provide methodological recommendations that may guide future studies.

The main goal of this study is to evaluate how to optimally select the best vibrotactile pattern to be used in a closed loop control of upper limb myoelectric prostheses as a feedback of the exerted force. To that end, we assessed both the selection of actuation patterns and the effects of the selection of frequency and amplitude parameters to discriminate between different feedback levels. A single vibrotactile actuator has been used to deliver the vibrations to subjects participating in the experiments. The results show no difference between pattern shapes in terms of feedback perception. Similarly, changes in amplitude level do not reflect significant improvement compared to changes in frequency. However, decreasing the number of feedback levels increases the accuracy of feedback perception and subject-specific variations are high for particular participants, showing that a fine-tuning of the parameters is necessary in a real-time application to upper limb prosthetics. In future works, the effects of training, location, and number of actuators will be assessed. This optimized selection will be tested in a real-time proportional myocontrol of a prosthetic hand.

Birdsong, like human speech, consists of a sequence of temporally precise movements acquired through vocal learning. The learning of such sequential vocalizations depends on the neural function of the motor cortex and basal ganglia. However, it is unknown how the connections between cortical and basal ganglia components contribute to vocal motor skill learning, as mammalian motor cortices serve multiple types of motor action and most experimentally tractable animals do not exhibit vocal learning. Here, we leveraged the zebra finch, a songbird, as an animal model to explore the function of the connectivity between cortex-like (HVC) and basal ganglia (area X), connected by HVC(x) projection neurons with temporally precise firing during singing. By specifically ablating HVC(x) neurons, juvenile zebra finches failed to copy tutored syllable acoustics and developed temporally unstable songs with less sequence consistency. In contrast, HVC(x) -ablated adults did not alter their learned song structure, but generated acoustic fluctuations and responded to auditory feedback disruption by the introduction of song deterioration, as did normal adults. These results indicate that the corticobasal ganglia input is important for learning the acoustic and temporal aspects of song structure, but not for generating vocal fluctuations that contribute to the maintenance of an already learned vocal pattern.

The sense of touch in our body is something that many of us take for granted. It is after all hard to imagine how we would move and utilize our arms and legs without any sensory feedback. For people who need to use hand prosthetics it is however very clear how they could improve their quality of life if they could “feel” with their hands once again. This could be realized using an artificial sense of touch, a sensory feedback system. There are different ways to accomplish the above. A simple solution would be to pair force sensors on the hand prosthesis with a device which provides mechanical feedback to the user. Such an approach is investigated in this report. The initial step was to build a prototype device which would allow for controlling a DC motor with force input from the user. This system was then used as a test bench to compare results from using two different sensor types, the FSR and SingleTact sensors. With the main findings from this report it can be concluded that a feedback system using both sensor types can work. While the error was reduced to some extent using PI control, further work will be necessary until the system can be used in practice., Sensory Feedback in Prosthetic Arms Sensory Feedback in Prosthetic ArmsThe sense of touch in our body is something that many of us take for granted. It is after all hard to imagine how we would move and utilize our arms and legs without any sensory feedback. For amputees who need to use hand prosthetics, it is however very clear how they could improve their quality of life if they could “feel” with their hands once again. An artificial sense of touch could be realized by creating a mechano-tactile feedback system: a system which would work by sending physical force feedback to the user. This is something was created in this project, and would work by providing a specified amount of force using servo motors, based upon user input. Is there an obstacle to create the above? Yes and no. The solution to the above A practical use-case for the above, is to mount the servo motors on a residual limb on the prosthetic arm user, for example this could be the upper arm. After touching objects with this device, the user would feel mechanical pressure on their upper arm from the motors. Mechano-tactile feedback using servomotors For the feedback system in this project two different types of sensors where used. The SingleTact capacitive force sensor as well as a FSR sensor (Interlink 402) were used. Both sensors where used separately and a test bench was used to compare the measurement results from both types. The servo motor used was a PQ23 Auctonix Linear Actuator, which work differently from the typical motor: it detracts and extends an arm into a specified position. The measurements where done as follows: the user would input specified force into a graphical user interface created for this project. The motor would then push towards the target plate (a material built to emulate the human upper arm), until the specified So how where the results? From the main findings it can be concluded that both sensor types can provide adequate measurements for use in a feedback system. It al

Birdsong, like human speech, consists of a sequence of temporally precise movements acquired through vocal learning. The learning of such sequential vocalizations depends on the neural function of the motor cortex and basal ganglia. However, it is unknown how the connections between cortical and basal ganglia components contribute to vocal motor skill learning, as mammalian motor cortices serve multiple types of motor action and most experimentally tractable animals do not exhibit vocal learning. Here, we leveraged the zebra finch, a songbird, as an animal model to explore the function of the connectivity between cortex-like (HVC) and basal ganglia (area X), connected by HVC(x) projection neurons with temporally precise firing during singing. By specifically ablating HVC(x) neurons, juvenile zebra finches failed to copy tutored syllable acoustics and developed temporally unstable songs with less sequence consistency. In contrast, HVC(x) -ablated adults did not alter their learned song structure, but generated acoustic fluctuations and responded to auditory feedback disruption by the introduction of song deterioration, as did normal adults. These results indicate that the corticobasal ganglia input is important for learning the acoustic and temporal aspects of song structure, but not for generating vocal fluctuations that contribute to the maintenance of an already learned vocal pattern.

The main goal of this study is to evaluate how to optimally select the best vibrotactile pattern to be used in a closed loop control of upper limb myoelectric prostheses as a feedback of the exerted force. To that end, we assessed both the selection of actuation patterns and the effects of the selection of frequency and amplitude parameters to discriminate between different feedback levels. A single vibrotactile actuator has been used to deliver the vibrations to subjects participating in the experiments. The results show no difference between pattern shapes in terms of feedback perception. Similarly, changes in amplitude level do not reflect significant improvement compared to changes in frequency. However, decreasing the number of feedback levels increases the accuracy of feedback perception and subject-specific variations are high for particular participants, showing that a fine-tuning of the parameters is necessary in a real-time application to upper limb prosthetics. In future works, the effects of training, location, and number of actuators will be assessed. This optimized selection will be tested in a real-time proportional myocontrol of a prosthetic hand.

It is widely accepted that unexpected sensory consequences of self-action engage the cerebellum. However, we currently lack consensus on where in the cerebellum, we find fine-grained differentiation to unexpected sensory feedback. This may result from methodological diversity in task-based human neuroimaging studies that experimentally alter the quality of self-generated sensory feedback. We gathered existing studies that manipulated sensory feedback using a variety of methodological approaches and performed activation likelihood estimation (ALE) meta-analyses. Only half of these studies reported cerebellar activation with considerable variation in spatial location. Consequently, ALE analyses did not reveal significantly increased likelihood of activation in the cerebellum despite the broad scientific consensus of the cerebellum's involvement. In light of the high degree of methodological variability in published studies, we tested for statistical dependence between methodological factors that varied across the published studies. Experiments that elicited an adaptive response to continuously altered sensory feedback more frequently reported activation in the cerebellum than those experiments that did not induce adaptation. These findings may explain the surprisingly low rate of significant cerebellar activation across brain imaging studies investigating unexpected sensory feedback. Furthermore, limitations of functional magnetic resonance imaging to probe the cerebellum could play a role as climbing fiber activity associated with feedback error processing may not be captured by it. We provide methodological recommendations that may guide future studies.

Sensory feedback plays an important role in maintaining steady and fluent speech production. So far, a majority of research in speech has focused on auditory feedback while not a lot has been done on somatosensory feedback. Thus, the current study aims to further explore the effect of vocal tract somatosensory feedback on auditory cortex activity during the process of audiomotor map learning. Due to extensive evidence for a phenomenon known as motor-induced suppression (MIS), the current study hypothesizes that cortical activity will be reduced in subjects after the establishment of learning. Using an MEG touchscreen speech synthesizer set- up, subjects heard a target vowel sound and were asked to touch a location on the touchscreen that matched the sound they heard. With each trial, subjects were given feedback in the form of the sound that corresponded to the location on the screen they touched, resulting in them eventually learning to map out each vowel sound to a target location on the screen. This set-up allowed a paradigm to test for the effect of audiomotor map learning. Then, using the NUTMEG software and Champagne source localization algorithm, data from each subject was analyzed before and after learning, as well as any potential differences between auditory and motor feedback or left and right auditory cortices were noted. Findings across all 4 conditions (left auditory cortex with auditory feedback, right auditory cortex with auditory feedback, left auditory cortex with auditory and somatomotor feedback, right auditory cortex with auditory and somatomotor feedback) in almost all the subjects found a statistically significant decrease in cortical activity following the establishment of audiomotor map learning. The current study sets up future work in which a variety of patient populations as well as different forms of feedback can be studied using a touchscreen speech synthesizing platform.

Background: There remains a substantial lack of evidence to support the use of foot orthoses as a conservative treatment option for idiopathic toe walking (ITW). Encouraging heel contact during gait is one of the primary goals of most interventions in paediatric ITW. Research Question: Does the combined treatment of high-top boots and orthoses increase the number of heel contacts during gait and change spatio-temporal gait parameters? Methods: This within subject designed randomised controlled trial recruited fifteen children diagnosed with ITW (n = 10 males). They were fitted with bilateral custom made rigid contoured carbon fibre foot orthoses placed inside high-top boots. To analyze the effect of this treatment, heel contacts and spatio-temporal parameters measured by an 8.3 m Gaitrite mat were compared to barefoot walking and shod walking. Result(s): An immediate increase in heel contact (p = 0.021) was observed in the combined treatment only. Gait changes included a large increase in stride time in the combined treatment condition compared to barefoot walking (p = 0.006). This was associated with a decrease in the percentage of swing phase in the gait cycle (p < 0.010), an increase in stance phase (p < 0.010) and an increase in double support time (p < 0.001). Significance: These results suggest the hardness and thickness of the shoe and stiffness of the orthosis midsole may lead to improved local dynamic stability and foot position awareness with increased sensory feedback provided through the entire length of the foot. Further research is indicated to validate this treatment option on long term outcomes in this population group.Copyright © 2018

Background: There remains a substantial lack of evidence to support the use of foot orthoses as a conservative treatment option for idiopathic toe walking (ITW). Encouraging heel contact during gait is one of the primary goals of most interventions in paediatric ITW. Research Question: Does the combined treatment of high-top boots and orthoses increase the number of heel contacts during gait and change spatio-temporal gait parameters? Methods: This within subject designed randomised controlled trial recruited fifteen children diagnosed with ITW (n = 10 males). They were fitted with bilateral custom made rigid contoured carbon fibre foot orthoses placed inside high-top boots. To analyze the effect of this treatment, heel contacts and spatio-temporal parameters measured by an 8.3 m Gaitrite mat were compared to barefoot walking and shod walking. Result(s): An immediate increase in heel contact (p = 0.021) was observed in the combined treatment only. Gait changes included a large increase in stride time in the combined treatment condition compared to barefoot walking (p = 0.006). This was associated with a decrease in the percentage of swing phase in the gait cycle (p < 0.010), an increase in stance phase (p < 0.010) and an increase in double support time (p < 0.001). Significance: These results suggest the hardness and thickness of the shoe and stiffness of the orthosis midsole may lead to improved local dynamic stability and foot position awareness with increased sensory feedback provided through the entire length of the foot. Further research is indicated to validate this treatment option on long term outcomes in this population group.Copyright © 2018

Sensory feedback possesses the possibility of adding a new dimension to many applications, including, but not limited to, prosthetics and surgical robots for improved control, virtual reality for incorporation of another sense, and phantom limb pain reduction for amputees. Electrotactile stimulation provides a compact, light-weight, energy efficient, highly responsive, and non-invasive option for sensory feedback; however, it has been found to commonly elicit unnatural or uncomfortable sensations for the user. To address this issue, this thesis was designed to test the impact of the different electrotactile stimulus parameters – current amplitude and polarity, pulse width, frequency, and waveform – on the user’s perceived sensation and afferent neural response. The relationship between sensation and neural response was also analysed. The aim of this thesis was to create guidelines to assist in the design and use of electrotactile stimulation. Neural data and matching psychophysical data from one healthy subject and purely psychophysical data from three others were gathered while applying electrotactile stimulations of different parameter combinations on the dorsal side of the hand or lower arm. Significant (p < 0.05) correlations and differences were found in all three relationships between electrotactile stimulus parameters, primary afferent response, and perceived sensation. Current (specifically negative) or pulse width control in monophasic waveforms were deemed most appropriate in applications that relay information through varying intensity. However, monophasic waveforms produced more discomfort, rendering biphasic waveforms more suitable when mild, local, and more natural sensations are of greater importance. Surprisingly, the data also suggested higher sensitivity to positive currents. While lower values of current amplitude and pulse width increased neural spike count, stimulus frequency could reliably control neural firing at all tested frequencies. Spi, Sensorisk återkoppling har möjlighet att drastiskt förbättra många användningsområden, t.ex. genom att bidra till enklare kontroll av proteser och kirurgiska robotar, mer verklighetstrogna VR-spel, och minskade fantomsmärtor hos patienter med amputeringar. Elektrisk hudstimulering erbjuder ett kompakt, lätt, energisnålt, hög-responsivt och icke-invasivt alternativ för sensorisk återkoppling – dock framkallar denna metod ofta onaturliga och obehagliga förnimmelser för användaren. Detta examensarbete bemöter detta problem genom att undersöka effekten av stimuleringsparametrar som strömstyrka, pulsbredd, frekvens och vågform på försökspersonens upplevda förnimmelse samt den afferenta nervresponsen. Även relationen mellan förnimmelse och nervrespons analyserades. Examensarbetets ändamål var att skapa riktlinjer för att förenkla designen och användandet av elektrisk hudstimulering. Nervdata med matchande psykofysiska data samlades från en frisk försöksperson, samt enbart psykofysiska data från tre andra, under olika elektriska hudstimuleringar (med varierande parametervärden) på handens dorsala sida eller på underarmen. Signifikanta (p < 0.05) korrelationer och skillnader fanns i alla tre relationer mellan parametrarna för elektrisk hudstimulering, primärafferent respons och upplevd förnimmelse. Kontroll av ström (i synnerhet negativ) eller pulsbredd i monofasisk vågform visade sig vara mest fördelaktigt i applikationer där information kommuniceras till användaren genom att variera den upplevda intensiteten. Dock skapade denna vågform mer obehag, och bifasiska vågformer bedömdes mer passande då milda, lokala, och mer naturliga förnimmelser är av högre värde. Positiv ström upplevdes, förvånande, starkare än negativ. Vid låga värden på ström och pulsbredd var dessa faktorer viktiga gällande antalet aktionspotentialer (AP), men stimuleringsfrekvensen kunde kontrollera antalet AP vid alla frekvenser. Mängden

Sensory feedback plays an important role in maintaining steady and fluent speech production. So far, a majority of research in speech has focused on auditory feedback while not a lot has been done on somatosensory feedback. Thus, the current study aims to further explore the effect of vocal tract somatosensory feedback on auditory cortex activity during the process of audiomotor map learning. Due to extensive evidence for a phenomenon known as motor-induced suppression (MIS), the current study hypothesizes that cortical activity will be reduced in subjects after the establishment of learning. Using an MEG touchscreen speech synthesizer set- up, subjects heard a target vowel sound and were asked to touch a location on the touchscreen that matched the sound they heard. With each trial, subjects were given feedback in the form of the sound that corresponded to the location on the screen they touched, resulting in them eventually learning to map out each vowel sound to a target location on the screen. This set-up allowed a paradigm to test for the effect of audiomotor map learning. Then, using the NUTMEG software and Champagne source localization algorithm, data from each subject was analyzed before and after learning, as well as any potential differences between auditory and motor feedback or left and right auditory cortices were noted. Findings across all 4 conditions (left auditory cortex with auditory feedback, right auditory cortex with auditory feedback, left auditory cortex with auditory and somatomotor feedback, right auditory cortex with auditory and somatomotor feedback) in almost all the subjects found a statistically significant decrease in cortical activity following the establishment of audiomotor map learning. The current study sets up future work in which a variety of patient populations as well as different forms of feedback can be studied using a touchscreen speech synthesizing platform.

Sensory feedback possesses the possibility of adding a new dimension to many applications, including, but not limited to, prosthetics and surgical robots for improved control, virtual reality for incorporation of another sense, and phantom limb pain reduction for amputees. Electrotactile stimulation provides a compact, light-weight, energy efficient, highly responsive, and non-invasive option for sensory feedback; however, it has been found to commonly elicit unnatural or uncomfortable sensations for the user. To address this issue, this thesis was designed to test the impact of the different electrotactile stimulus parameters – current amplitude and polarity, pulse width, frequency, and waveform – on the user’s perceived sensation and afferent neural response. The relationship between sensation and neural response was also analysed. The aim of this thesis was to create guidelines to assist in the design and use of electrotactile stimulation. Neural data and matching psychophysical data from one healthy subject and purely psychophysical data from three others were gathered while applying electrotactile stimulations of different parameter combinations on the dorsal side of the hand or lower arm. Significant (p < 0.05) correlations and differences were found in all three relationships between electrotactile stimulus parameters, primary afferent response, and perceived sensation. Current (specifically negative) or pulse width control in monophasic waveforms were deemed most appropriate in applications that relay information through varying intensity. However, monophasic waveforms produced more discomfort, rendering biphasic waveforms more suitable when mild, local, and more natural sensations are of greater importance. Surprisingly, the data also suggested higher sensitivity to positive currents. While lower values of current amplitude and pulse width increased neural spike count, stimulus frequency could reliably control neural firing at all tested frequencies. Spi, Sensorisk återkoppling har möjlighet att drastiskt förbättra många användningsområden, t.ex. genom att bidra till enklare kontroll av proteser och kirurgiska robotar, mer verklighetstrogna VR-spel, och minskade fantomsmärtor hos patienter med amputeringar. Elektrisk hudstimulering erbjuder ett kompakt, lätt, energisnålt, hög-responsivt och icke-invasivt alternativ för sensorisk återkoppling – dock framkallar denna metod ofta onaturliga och obehagliga förnimmelser för användaren. Detta examensarbete bemöter detta problem genom att undersöka effekten av stimuleringsparametrar som strömstyrka, pulsbredd, frekvens och vågform på försökspersonens upplevda förnimmelse samt den afferenta nervresponsen. Även relationen mellan förnimmelse och nervrespons analyserades. Examensarbetets ändamål var att skapa riktlinjer för att förenkla designen och användandet av elektrisk hudstimulering. Nervdata med matchande psykofysiska data samlades från en frisk försöksperson, samt enbart psykofysiska data från tre andra, under olika elektriska hudstimuleringar (med varierande parametervärden) på handens dorsala sida eller på underarmen. Signifikanta (p < 0.05) korrelationer och skillnader fanns i alla tre relationer mellan parametrarna för elektrisk hudstimulering, primärafferent respons och upplevd förnimmelse. Kontroll av ström (i synnerhet negativ) eller pulsbredd i monofasisk vågform visade sig vara mest fördelaktigt i applikationer där information kommuniceras till användaren genom att variera den upplevda intensiteten. Dock skapade denna vågform mer obehag, och bifasiska vågformer bedömdes mer passande då milda, lokala, och mer naturliga förnimmelser är av högre värde. Positiv ström upplevdes, förvånande, starkare än negativ. Vid låga värden på ström och pulsbredd var dessa faktorer viktiga gällande antalet aktionspotentialer (AP), men stimuleringsfrekvensen kunde kontrollera antalet AP vid alla frekvenser. Mängden

Peripheral intraneural stimulation can provide tactile information to amputees. However, efforts are still necessary to identify encoding strategy eliciting percepts that are felt as both natural and effective for prosthesis control. Here we compared the naturalness and efficacy of different encoding strategies to deliver neural stimulation to trans-radial amputees implanted with intraneural electrodes. Biomimetic frequency modulation was perceived as more natural, while amplitude modulation enabled better performance in tasks requiring fine identification of the applied force. Notably, the optimal combination of naturalness and sensitivity of the tactile feedback can be achieved with “hybrid” encoding strategies based on simultaneous biomimetic frequency and amplitude neuromodulation. These strategies improved the gross manual dexterity of the subjects during functional task while maintaining high levels of manual accuracy. They also improved prosthesis embodiment, reducing abnormal phantom limb perceptions (“telescoping effect”). Hybrid strategies are able to provide highly sensitive and natural percepts and should be preferred. Video Abstract: Sensory encoding strategies are used to convey sensory information to upper limb amputees. Valle et al. present strategies based on biomimetic approaches that improve sensation naturalness, tactile sensitivity, manual dexterity, and prosthesis embodiment.

Background: Many aspects of post-stroke gait-rehabilitation are based on low-level evidence or expert opinion. Neuroscientific principles are often not considered when evaluating the impact of interventions. The use of walking-aids including canes and rollators, although widely used for long periods, has primarily been investigated to assess the immediate kinetic, kinematic or physiological effects. The long-term impact on neural structures und functions remains unclear.Methods: A literature review of the function of and factors affecting plasticity of spinal interneuronal-networks and central-pattern-generators (CPG) in healthy and post-stroke patients. The relevance of these mechanisms for gait recovery and the potential impact of walking-aids is discussed.Results: Afferent-input to spinal-networks influences motor-output and spinal and cortical plasticity. Disrupted input may adversely affect post-stroke plasticity and functional recovery. Joint and muscle unloading and decoupling from four-limb CPG control may be particularly relevant.Conclusions: Canes and rollators disrupt afferent-input and may negatively affect the recovery of gait. (C) 2016 Elsevier Ltd. All rights reserved.

ABSTRACT: We hypothesize that changes in motor behavior in individuals with low-back pain are adaptations aimed at minimizing the real or perceived risk of further pain. Through reinforcement learning, pain and subsequent adaptions result in less dynamic motor behavior, leading to increased loading and impoverished sensory feedback, which contributes to cortical reorganization and proprioceptive impairments that reduce the ability to control lumbar movement in a robust manner.

Mechanical perturbations applied to the wrist joint typically evoke a stereotypical sequence of cortical and muscle responses. The early cortical responses (<100 ms) are thought be involved in the “rapid” transcortical reaction to the perturbation while the late cortical responses (>100 ms) are related to the “slow” transcortical reaction. Although previous studies indicated that both responses involve the primary motor cortex, it remains unclear if both responses are engaged by the same effective connectivity in the cortical network. To answer this question, we investigated the effective connectivity cortical network after a “ramp-and-hold” mechanical perturbation, in both the early (<100 ms) and late (>100 ms) periods, using dynamic causal modeling. Ramp-and-hold perturbations were applied to the wrist joint while the subject maintained an isometric wrist flexion. Cortical activity was recorded using a 128-channel electroencephalogram (EEG). We investigated how the perturbation modulated the effective connectivity for the early and late periods. Bayesian model comparisons suggested that different effective connectivity networks are engaged in these two periods. For the early period, we found that only a few cortico-cortical connections were modulated, while more complicated connectivity was identified in the cortical network during the late period with multiple modulated cortico-cortical connections. The limited early cortical network likely allows for a rapid muscle response without involving high-level cognitive processes, while the complexity of the late network may facilitate coordinated responses., Biomechatronics & Human-Machine Control

Neural coupling between the central nervous system and the periphery is essential for the neural control of movement. Corticomuscular coherence is a popular linear technique to assess synchronised oscillatory activity in the sensorimotor system. This oscillatory coupling originates from ascending somatosensory feedback and descending motor commands. However, corticomuscular coherence cannot separate this bidirectionality. Furthermore, the sensorimotor system is nonlinear, resulting in cross-frequency coupling. Cross-frequency oscillations cannot be assessed nor exploited by linear measures. Here, we emphasise the need of novel coupling measures, which provide directionality and acknowledge nonlinearity, to unveil neural coupling in the sensorimotor system. We highlight recent advances in the field and argue that assessing directionality and nonlinearity of neural coupling will break new ground in the study of the control of movement in healthy and neurologically impaired individuals., Biomechatronics & Human-Machine Control

This master thesis is about improvement, optimization and further development of the sensory feedback in a prosthetic hand previously investigated at the department of Biomedical Engineering in Lund. The first approach will be to investigate and further see into the need of a sensory feedback in hand prostheses. There were several reports that showed that the lack of sensory feedback in hand prostheses increased the rejection factor for the user. The aim will be to investigate necessary functions needed in a sensory feedback system in hand prosthesis and look into appropriate hardware that fulfills these requirements. The core hardware is built on two Arduino Nano circuits. The force sensing sensors, electromyography sensors and the sensory feedback vibrators are the main components for the setup. To fully utilize the capacity of the micro controllers and to fulfill the requirements in the aim components such as a real time clock, data logger, Bluetooth and a calibration mode will be applied in the setup. Subsequently a printed circuit board will be developed while investigating the robustness, rapidity and stability of the Arduino setup. The result of this project is ready to test EMG controlled hand prosthesis with sensory feedback. The response time is around 6 ms. In addition to this, several features have been added to the setup such as an calibration mode with Bluetooth interface, a real time clock and the opportunity to store information on an SD card. An implemented sleep mode that makes the setup as power saving as possible is also implemented., Vibrotactile sensory feedback in hand prostheses Reports showed that the lack of sensory feedback in myoelectric hand prostheses increased the rejection factor for the user. Purpose: The aim will be to investigate necessary functions needed in a sensory feedback system in a hand prosthesis and look into appropriate hardware that fulfills these requirements. Methods: The core hardware is built on two Arduino Nano circuits. The force sensing sensors, electromyography sensors and the sensory feedback vibrators are the main components for the setup. Results: This project is ready to test electromyographic controlled hand prosthesis with sensory feedback. In addition to this, several features have been added to the setup such as an calibration mode with Bluetooth interface, a real time clock and the opportunity to store information on an SD card. Conclusions: Even though this project resulted in a successful, functioning sensory feedback system, it needs to be evaluated and preferably on amputees.

This master thesis is about improvement, optimization and further development of the sensory feedback in a prosthetic hand previously investigated at the department of Biomedical Engineering in Lund. The first approach will be to investigate and further see into the need of a sensory feedback in hand prostheses. There were several reports that showed that the lack of sensory feedback in hand prostheses increased the rejection factor for the user. The aim will be to investigate necessary functions needed in a sensory feedback system in hand prosthesis and look into appropriate hardware that fulfills these requirements. The core hardware is built on two Arduino Nano circuits. The force sensing sensors, electromyography sensors and the sensory feedback vibrators are the main components for the setup. To fully utilize the capacity of the micro controllers and to fulfill the requirements in the aim components such as a real time clock, data logger, Bluetooth and a calibration mode will be applied in the setup. Subsequently a printed circuit board will be developed while investigating the robustness, rapidity and stability of the Arduino setup. The result of this project is ready to test EMG controlled hand prosthesis with sensory feedback. The response time is around 6 ms. In addition to this, several features have been added to the setup such as an calibration mode with Bluetooth interface, a real time clock and the opportunity to store information on an SD card. An implemented sleep mode that makes the setup as power saving as possible is also implemented., Vibrotactile sensory feedback in hand prostheses Reports showed that the lack of sensory feedback in myoelectric hand prostheses increased the rejection factor for the user. Purpose: The aim will be to investigate necessary functions needed in a sensory feedback system in a hand prosthesis and look into appropriate hardware that fulfills these requirements. Methods: The core hardware is built on two Arduino Nano circuits. The force sensing sensors, electromyography sensors and the sensory feedback vibrators are the main components for the setup. Results: This project is ready to test electromyographic controlled hand prosthesis with sensory feedback. In addition to this, several features have been added to the setup such as an calibration mode with Bluetooth interface, a real time clock and the opportunity to store information on an SD card. Conclusions: Even though this project resulted in a successful, functioning sensory feedback system, it needs to be evaluated and preferably on amputees.

Background: Many aspects of post-stroke gait-rehabilitation are based on low-level evidence or expert opinion. Neuroscientific principles are often not considered when evaluating the impact of interventions. The use of walking-aids including canes and rollators, although widely used for long periods, has primarily been investigated to assess the immediate kinetic, kinematic or physiological effects. The long-term impact on neural structures und functions remains unclear.Methods: A literature review of the function of and factors affecting plasticity of spinal interneuronal-networks and central-pattern-generators (CPG) in healthy and post-stroke patients. The relevance of these mechanisms for gait recovery and the potential impact of walking-aids is discussed.Results: Afferent-input to spinal-networks influences motor-output and spinal and cortical plasticity. Disrupted input may adversely affect post-stroke plasticity and functional recovery. Joint and muscle unloading and decoupling from four-limb CPG control may be particularly relevant.Conclusions: Canes and rollators disrupt afferent-input and may negatively affect the recovery of gait. (C) 2016 Elsevier Ltd. All rights reserved.

ABSTRACT: We hypothesize that changes in motor behavior in individuals with low-back pain are adaptations aimed at minimizing the real or perceived risk of further pain. Through reinforcement learning, pain and subsequent adaptions result in less dynamic motor behavior, leading to increased loading and impoverished sensory feedback, which contributes to cortical reorganization and proprioceptive impairments that reduce the ability to control lumbar movement in a robust manner.

Neural coupling between the central nervous system and the periphery is essential for the neural control of movement. Corticomuscular coherence is a popular linear technique to assess synchronised oscillatory activity in the sensorimotor system. This oscillatory coupling originates from ascending somatosensory feedback and descending motor commands. However, corticomuscular coherence cannot separate this bidirectionality. Furthermore, the sensorimotor system is nonlinear, resulting in cross-frequency coupling. Cross-frequency oscillations cannot be assessed nor exploited by linear measures. Here, we emphasise the need of novel coupling measures, which provide directionality and acknowledge nonlinearity, to unveil neural coupling in the sensorimotor system. We highlight recent advances in the field and argue that assessing directionality and nonlinearity of neural coupling will break new ground in the study of the control of movement in healthy and neurologically impaired individuals., Biomechatronics & Human-Machine Control

Mechanical perturbations applied to the wrist joint typically evoke a stereotypical sequence of cortical and muscle responses. The early cortical responses (<100 ms) are thought be involved in the “rapid” transcortical reaction to the perturbation while the late cortical responses (>100 ms) are related to the “slow” transcortical reaction. Although previous studies indicated that both responses involve the primary motor cortex, it remains unclear if both responses are engaged by the same effective connectivity in the cortical network. To answer this question, we investigated the effective connectivity cortical network after a “ramp-and-hold” mechanical perturbation, in both the early (<100 ms) and late (>100 ms) periods, using dynamic causal modeling. Ramp-and-hold perturbations were applied to the wrist joint while the subject maintained an isometric wrist flexion. Cortical activity was recorded using a 128-channel electroencephalogram (EEG). We investigated how the perturbation modulated the effective connectivity for the early and late periods. Bayesian model comparisons suggested that different effective connectivity networks are engaged in these two periods. For the early period, we found that only a few cortico-cortical connections were modulated, while more complicated connectivity was identified in the cortical network during the late period with multiple modulated cortico-cortical connections. The limited early cortical network likely allows for a rapid muscle response without involving high-level cognitive processes, while the complexity of the late network may facilitate coordinated responses., Biomechatronics & Human-Machine Control

Exaggerated sensory activity has been assumed to contribute to functional impairment following lesion of the central motor pathway. However, recent studies have suggested that sensory contribution to muscle activity during gait is reduced in stroke patients and children with cerebral palsy (CP). We investigated whether this also occurs in CP adults and whether daily treadmill training is accompanied by alterations in sensory contribution to muscle activity. Seventeen adults with CP and 12 uninjured individuals participated. The participants walked on a treadmill while a robotized ankle-foot orthosis applied unload perturbations at the ankle, thereby removing sensory feedback naturally activated during push-off. Reduction of electromyographic (EMG) activity in the soleus muscle caused by unloads was compared and related to kinematics and ankle joint stiffness measurements. Similar measures were obtained after 6 wk of gait training. We found that sensory contribution to soleus EMG activation was reduced in CP adults compared with uninjured adults. The lowest contribution of sensory feedback was found in participants with lowest maximal gait speed. This was related to increased ankle plantar flexor stiffness. Six weeks of gait training did not alter the contribution of sensory feedback. We conclude that exaggerated sensory activity is unlikely to contribute to impaired gait in CP adults, because sensory contribution to muscle activity during gait was reduced compared with in uninjured individuals. Increased passive stiffness around the ankle joint is likely to diminish sensory feedback during gait so that a larger part of plantar flexor muscle activity must be generated by descending motor commands. NEW & NOTEWORTHY Findings suggest that adults with cerebral palsy have less contribution of sensory feedback to ongoing soleus muscle activation during push-off than uninjured individuals. Increased passive stiffness around the ankle joint is likely to diminishn sens

Objective: To evaluate a newly developed biofeedback device enabling lower-limb amputees to identify various floor conditions. Design: Self-control with repeated measures (with and without the biofeedback device) within the amputee group, and group control comparing between amputee and nonamputee groups. Setting: University locomotion laboratory. Participants: Five lower-limb amputees and 8 nonamputees (N=13). Interventions: A wearable biofeedback device, which identified different floor conditions by analyzing the force patterns under the prosthetic feet and provided vibration cues in response to different floor conditions, was provided to the amputees. Main Outcome Measures: The subjects stepped on a foam platform concealing a small object or no object at 1 of the 4 locations of the foot sole. Subjects were asked whether there was a small object under their feet and the location of the object if it existed. The test was repeated with 4 different object types and 4 object locations. The success rate of floor identification was evaluated. Results: Without the biofeedback device, nonamputee subjects (76.56%) identified floor conditions better than amputees (22.5%) significantly (P<.001). On using the biofeedback device, the amputees significantly improved (P<.01) their success rate showing no significant difference (P=.746) compared with the nonamputees. No significant differences were found among object types (P=.689). Conclusions: Amputees performed significantly worse than nonamputees in recognizing the different floor conditions used in this experiment. With the biofeedback device, amputees significantly improved their abilities in identifying different floor conditions. Future attempts could configure the device to allow it to provide warning signals in response to fall-inducing conditions.

Technological advancements have led to the development of numerous wearable robotic devices for the physical assistance and restoration of human locomotion. While many challenges remain with respect to the mechanical design of such devices, it is at least equally challenging and important to develop strategies to control them in concert with the intentions of the user. This work reviews the state-of-the-art techniques for controlling portable active lower limb prosthetic and orthotic (P/O) devices in the context of locomotive activities of daily living (ADL), and considers how these can be interfaced with the user’s sensory-motor control system. This review underscores the practical challenges and opportunities associated with P/O control, which can be used to accelerate future developments in this field. Furthermore, this work provides a classification scheme for the comparison of the various control strategies. As a novel contribution, a general framework for the control of portable gait-assistance devices is proposed. This framework accounts for the physical and informatic interactions between the controller, the user, the environment, and the mechanical device itself. Such a treatment of P/Os – not as independent devices, but as actors within an ecosystem – is suggested to be necessary to structure the next generation of intelligent and multifunctional controllers. Each element of the proposed framework is discussed with respect to the role that it plays in the assistance of locomotion, along with how its states can be sensed as inputs to the controller. The reviewed controllers are shown to fit within different levels of a hierarchical scheme, which loosely resembles the structure and functionality of the nominal human central nervous system (CNS). Active and passive safety mechanisms are considered to be central aspects underlying all of P/O design and control, and are shown to be critical for regulatory approval of such devices for real-world use. The works d, Biomechanical Engineering, Mechanical, Maritime and Materials Engineering

BioMechanical Engineering, Mechanical, Maritime and Materials Engineering

BioMechanical Engineering, Mechanical, Maritime and Materials Engineering

Technological advancements have led to the development of numerous wearable robotic devices for the physical assistance and restoration of human locomotion. While many challenges remain with respect to the mechanical design of such devices, it is at least equally challenging and important to develop strategies to control them in concert with the intentions of the user. This work reviews the state-of-the-art techniques for controlling portable active lower limb prosthetic and orthotic (P/O) devices in the context of locomotive activities of daily living (ADL), and considers how these can be interfaced with the user’s sensory-motor control system. This review underscores the practical challenges and opportunities associated with P/O control, which can be used to accelerate future developments in this field. Furthermore, this work provides a classification scheme for the comparison of the various control strategies. As a novel contribution, a general framework for the control of portable gait-assistance devices is proposed. This framework accounts for the physical and informatic interactions between the controller, the user, the environment, and the mechanical device itself. Such a treatment of P/Os – not as independent devices, but as actors within an ecosystem – is suggested to be necessary to structure the next generation of intelligent and multifunctional controllers. Each element of the proposed framework is discussed with respect to the role that it plays in the assistance of locomotion, along with how its states can be sensed as inputs to the controller. The reviewed controllers are shown to fit within different levels of a hierarchical scheme, which loosely resembles the structure and functionality of the nominal human central nervous system (CNS). Active and passive safety mechanisms are considered to be central aspects underlying all of P/O design and control, and are shown to be critical for regulatory approval of such devices for real-world use. The works d, Biomechanical Engineering, Mechanical, Maritime and Materials Engineering

Résumé : Suite à une lésion de la moelle épinière, divers comportements moteurs invalidants, tels des spasmes peuvent apparaître. Les traitements actuels pour la spasticité causent divers effets secondaires, dont une réduction de la capacité locomotrice des patients. La recherche de traitements non invasifs et non pharmacologiques permettant de réduire la spasticité sans affecter la récupération fonctionnelle du patient s’avère donc un enjeu prioritaire. Par ailleurs, une réduction des spasmes rythmiques peut être observée lorsque la peau lombosacrée est pincée. Ce potentiel inhibiteur d’une stimulation cutanée tonique est également perçu chez l’animal comme le lapin et le chat suite à une perte des voies supraspinales. Par contre, bien que ce type de stimulation semble efficace pour réduire la spasticité, son effet sur la capacité locomotrice n’a toujours pas été évalué. L’objectif du projet était de déterminer l’effet d’un pincement de la peau à divers niveaux lombaires sur la locomotion du chat ayant une lésion de la moelle épinière. Six chats implantés chroniquement pour l’électromyographie (EMG) ont subi une lésion complète de la moelle épinière au niveau thoracique et ont été entraînés sur tapis roulant pour récupérer une fonction locomotrice des pattes postérieures. L’effet d’une stimulation de 6 sites cutanés sur la ligne médiane au niveau des vertèbres lombaires L2 à L7 a été évalué lors de marche à 0.4 m/s via des analyses cinématiques et EMG. Les résultats obtenus démontrent que la zone cutanée perturbant le plus l’activité locomotrice se trouve sur la ligne médiane au niveau lombaire L4. À ce niveau, une diminution de l’activité des extenseurs et des fléchisseurs est perçue au niveau de l’EMG. De plus, des modifications du patron locomoteur comme un positionnement plus caudal de la patte lors de son contact et de son décollage sont également visibles, tout comme une perte du support de poids (force de réaction au sol). La coordination spatiale entre les

Providing functionally effective sensory feedback to users of prosthetics is a largely unsolved challenge. Traditional solutions require high band-widths for providing feedback for the control of manipulation and yet have been largely unsuccessful. In this study, we have explored a strategy that relies on temporally discrete sensory feedback that is technically simple to provide. According to the Discrete Event-driven Sensory feedback Control (DESC) policy, motor tasks in humans are organized in phases delimited by means of sensory encoded discrete mechanical events. To explore the applicability of DESC for control, we designed a paradigm in which healthy humans operated an artificial robot hand to lift and replace an instrumented object, a task that can readily be learned and mastered under visual control. Assuming that the central nervous system of humans naturally organizes motor tasks based on a strategy akin to DESC, we delivered short-lasting vibrotactile feedback related to events that are known to forcefully affect progression of the grasp-lift-and-hold task. After training, we determined whether the artificial feedback had been integrated with the sensorimotor control by introducing short delays and we indeed observed that the participants significantly delayed subsequent phases of the task. This study thus gives support to the DESC policy hypothesis. Moreover, it demonstrates that humans can integrate temporally discrete sensory feedback while controlling an artificial hand and invites further studies in which inexpensive, noninvasive technology could be used in clever ways to provide physiologically appropriate sensory feedback in upper limb prosthetics with much lower band-width requirements than with traditional solutions.

Background: Robotic assisted minimally invasive surgery systems not only have the advantages of traditional laparoscopic procedures but also restore the surgeon's hand-eye coordination and improve the surgeon's precision by filtering hand tremors. Unfortunately, these benefits have come at the expense of the surgeon's ability to feel. Several research efforts have already attempted to restore this feature and study the effects of force feedback in robotic systems. The proposed methods and studies have some shortcomings. The main focus of this research is to overcome some of these limitations and to study the effects of force feedback in palpation in a more realistic fashion. Material(s) and Method(s): A parallel robot assisted minimally invasive surgery system (PRAMiSS) with force feedback capabilities was employed to study the effects of realistic force feedback in palpation of artificial tissue samples. PRAMiSS is capable of actually measuring the tip/tissue interaction forces directly from the surgery site. Four sets of experiments using only vision feedback, only force feedback, simultaneous force and vision feedback and direct manipulation were conducted to evaluate the role of sensory feedback from sideways tip/tissue interaction forces with a scale factor of 100% in characterising tissues of varying stiffness. Twenty human subjects were involved in the experiments for at least 1440 trials. Friedman and Wilcoxon signed-rank tests were employed to statistically analyse the experimental results. Result(s): Providing realistic force feedback in robotic assisted surgery systems improves the quality of tissue characterization procedures. Force feedback capability also increases the certainty of characterizing soft tissues compared with direct palpation using the lateral sides of index fingers. Conclusion(s): The force feedback capability can improve the quality of palpation and characterization of soft tissues of varying stiffness by restoring sense of touch in rob

Background: Robotic assisted minimally invasive surgery systems not only have the advantages of traditional laparoscopic procedures but also restore the surgeon's hand-eye coordination and improve the surgeon's precision by filtering hand tremors. Unfortunately, these benefits have come at the expense of the surgeon's ability to feel. Several research efforts have already attempted to restore this feature and study the effects of force feedback in robotic systems. The proposed methods and studies have some shortcomings. The main focus of this research is to overcome some of these limitations and to study the effects of force feedback in palpation in a more realistic fashion. Material(s) and Method(s): A parallel robot assisted minimally invasive surgery system (PRAMiSS) with force feedback capabilities was employed to study the effects of realistic force feedback in palpation of artificial tissue samples. PRAMiSS is capable of actually measuring the tip/tissue interaction forces directly from the surgery site. Four sets of experiments using only vision feedback, only force feedback, simultaneous force and vision feedback and direct manipulation were conducted to evaluate the role of sensory feedback from sideways tip/tissue interaction forces with a scale factor of 100% in characterising tissues of varying stiffness. Twenty human subjects were involved in the experiments for at least 1440 trials. Friedman and Wilcoxon signed-rank tests were employed to statistically analyse the experimental results. Result(s): Providing realistic force feedback in robotic assisted surgery systems improves the quality of tissue characterization procedures. Force feedback capability also increases the certainty of characterizing soft tissues compared with direct palpation using the lateral sides of index fingers. Conclusion(s): The force feedback capability can improve the quality of palpation and characterization of soft tissues of varying stiffness by restoring sense of touch in rob