Brain response to focal vibro-tactile stimulation prior to muscle contraction

This paper presents a single case study of an on-going study evaluating cortical association with facilitation and management of vibro-tactile stimulation applied prior to voluntary muscle contraction. The study consisted of three repetitions of relaxation phase during which vibrations are applied, and a contraction phase. EEG and EMG data was collected to determine muscle and brain activation patterns. The EEG analysis of the mu waves during relaxation + vibration phase seem to indicate sensory cortex activation during focal muscle vibrations. With repetitiveness of vibrations, an increase in maximal calculated mu power was observed that could suggest optimization of the muscle fibers prior to the contraction. When contraction is performed, mu waves are desynchronizing with the movement execution. The analysis of the last relaxation period indicate that the muscle itself facilitates the last contraction locally possibly due to cortical learning

VIBROfocus: Design of a focal vibro-tactile robotic-assistive system for spasticity rehabilitation

The main focus of spasticity treatment is to alleviate pain, improve function and reduce risk of additional complications. In this paper the design of a robotic system with enhanced focal vibro-tactile stimulation for the treatment of spasticity in the upper limbs is presented. Building on emerging evidence on the use of vibrations in the treatment of spasticity, we propose a new integrated approach. Our design combines the use of vibro-tactile stimulation of the high tone muscle with robotic movement assistance to augment rehabilitation outcomes in patients with spasticity in the upper limbs

Investigation of the feasibility of using focal vibratory stimulation with robotic aided therapy for spasticity rehabilitation in spinal cord injury

The occurrence of a traumatic spinal cord injury is in hundreds of thousands of people every year. Survivors are left with loss of many bodily functions, loss of sensation below the point of injury and many more painful and uncomfortable repercussions which interfere with activities of daily living. Over 70% of people with SCI develop spasticity: abnormally increased muscle tone and connected joint stiffness that interfere with residual volitional control of the limbs. Treatments for spasticity include many pharmacological and non-pharmacological techniques, however many of them have severe sideeffects. Evidence suggest the use of vibratory stimulation to relieve repercussions of spasticity, despite not agreeing on the most advantageous protocol. This thesis evaluated effects that focal vibratory stimulation have on the muscle performance. Within two studies, focal muscle vibration is compared against different application conditions such as timing and location. The results suggests that if focal vibrations are applied to the relaxed muscle, the increase in muscle's force is observed. Analysis of the cortical waves indicates minimal cortical involvement in vibratory stimulation modulation. On the other hand, FV applied of the connected tendon/bone imposed to a contraction seems to have a potential to increase muscle's activation. There is evidence that motor cortex is responding to this stimulation to stabilise the muscle in order to perform the contraction. Within clinical trial, focal muscle vibratory stimulation is employed in total of 6 interventional sessions while a joint's spastic exor and extensor muscles were relaxed. Spasticity appears to be reduced as a consequence of the stimulation. Moreover, engaging the joint into robotic-aided therapy increase volitional control of the wrist, according to the analysis of the active range of motion, joint stiffness and kinematic parameters associated to the movement. The measurement and movement facilitation device used in the clinical trial was designed and developed in accordance to the spasticity and spinal cord injury repercussions consideration. The studies conducted for this thesis demonstrated feasibility and potential for the use of focal muscle vibratory stimulation to enhance muscle power in healthy muscles but also relieve consequences of spasticity. Vibrations combined with movement robotic-aided therapy have a prospects to enhance motor control

Why orthotic devices could be of help in the management of Movement Disorders in the young

BACKGROUND: Movement Disorders (MD) are a class of disease that impair the daily activities of patients, conditioning their sensorimotor, cognitive and behavioural capabilities. Nowadays, the general management of patients with MD is based on rehabilitation, pharmacological treatments, surgery, and traditional splints. Although some attempts have been made to devise specific orthoses for the rehabilitation of patients affected by MD, especially the younger ones, those devices have received limited attention. MAIN BODY: This paper will principally discuss the case of upper limb rehabilitation in Childhood Dyskinesia (CD), a complex motor disease that affects paediatric patients. Through a critical review of the present solutions and a discussion about the neurophysiological characteristics of the disease, the study will lead to the formulation of desirable features of a possible new upper-limb orthosis. CONCLUSIONS: Design principles will be derived to provide specialised orthoses for the dynamic control of posture and the stabilisation of voluntary movements: those include using biomechanical actions and enhanced proprioception to support the sensorimotor rehabilitation of the children affected by CD. A similar approach could be advantageously applied in other MD-related conditions, especially with hyperkinetic and/or hypertonic traits

Understanding motor control in humans to improve rehabilitation robots

Recent reviews highlighted the limited results of robotic rehabilitation and the low quality of evidences in this field. Despite the worldwide presence of several robotic infrastructures, there is still a lack of knowledge about the capabilities of robotic training effect on the neural control of movement. To fill this gap, a step back to motor neuroscience is needed: the understanding how the brain works in the generation of movements, how it adapts to changes and how it acquires new motor skills is fundamental. This is the rationale behind my PhD project and the contents of this thesis: all the studies included in fact examined changes in motor control due to different destabilizing conditions, ranging from external perturbations, to self-generated disturbances, to pathological conditions. Data on healthy and impaired adults have been collected and quantitative and objective information about kinematics, dynamics, performance and learning were obtained for the investigation of motor control and skill learning. Results on subjects with cervical dystonia show how important assessment is: possibly adequate treatments are missing because the physiological and pathological mechanisms underlying sensorimotor control are not routinely addressed in clinical practice. These results showed how sensory function is crucial for motor control. The relevance of proprioception in motor control and learning is evident also in a second study. This study, performed on healthy subjects, showed that stiffness control is associated with worse robustness to external perturbations and worse learning, which can be attributed to the lower sensitiveness while moving or co-activating. On the other hand, we found that the combination of higher reliance on proprioception with \u201cdisturbance training\u201d is able to lead to a better learning and better robustness. This is in line with recent findings showing that variability may facilitate learning and thus can be exploited for sensorimotor recovery. Based on these results, in a third study, we asked participants to use the more robust and efficient strategy in order to investigate the control policies used to reject disturbances. We found that control is non-linear and we associated this non-linearity with intermittent control. As the name says, intermittent control is characterized by open loop intervals, in which movements are not actively controlled. We exploited the intermittent control paradigm for other two modeling studies. In these studies we have shown how robust is this model, evaluating it in two complex situations, the coordination of two joints for postural balance and the coordination of two different balancing tasks. It is an intriguing issue, to be addressed in future studies, to consider how learning affects intermittency and how this can be exploited to enhance learning or recovery. The approach, that can exploit the results of this thesis, is the computational neurorehabilitation, which mathematically models the mechanisms underlying the rehabilitation process, with the aim of optimizing the individual treatment of patients. Integrating models of sensorimotor control during robotic neurorehabilitation, might lead to robots that are fully adaptable to the level of impairment of the patient and able to change their behavior accordingly to the patient\u2019s intention. This is one of the goals for the development of rehabilitation robotics and in particular of Wristbot, our robot for wrist rehabilitation: combining proper assessment and training protocols, based on motor control paradigms, will maximize robotic rehabilitation effects

Towards Natural Control of Artificial Limbs

The use of implantable electrodes has been long thought as the solution for a more natural control of artificial limbs, as these offer access to long-term stable and physiologically appropriate sources of control, as well as the possibility to elicit appropriate sensory feedback via neurostimulation. Although these ideas have been explored since the 1960’s, the lack of a long-term stable human-machine interface has prevented the utilization of even the simplest implanted electrodes in clinically viable limb prostheses.In this thesis, a novel human-machine interface for bidirectional communication between implanted electrodes and the artificial limb was developed and clinically implemented. The long-term stability was achieved via osseointegration, which has been shown to provide stable skeletal attachment. By enhancing this technology as a communication gateway, the longest clinical implementation of prosthetic control sourced by implanted electrodes has been achieved, as well as the first in modern times. The first recipient has used it uninterruptedly in daily and professional activities for over one year. Prosthetic control was found to improve in resolution while requiring less muscular effort, as well as to be resilient to motion artifacts, limb position, and environmental conditions.In order to support this work, the literature was reviewed in search of reliable and safe neuromuscular electrodes that could be immediately used in humans. Additional work was conducted to improve the signal-to-noise ratio and increase the amount of information retrievable from extraneural recordings. Different signal processing and pattern recognition algorithms were investigated and further developed towards real-time and simultaneous prediction of limb movements. These algorithms were used to demonstrate that higher functionality could be restored by intuitive control of distal joints, and that such control remains viable over time when using epimysial electrodes. Lastly, the long-term viability of direct nerve stimulation to produce intuitive sensory feedback was also demonstrated.The possibility to permanently and reliably access implanted electrodes, thus making them viable for prosthetic control, is potentially the main contribution of this work. Furthermore, the opportunity to chronically record and stimulate the neuromuscular system offers new venues for the prediction of complex limb motions and increased understanding of somatosensory perception. Therefore, the technology developed here, combining stable attachment with permanent and reliable human-machine communication, is considered by the author as a critical step towards more functional artificial limbs

Neuroplasticity induced by peripheral nerve stimulation

PhD ThesisNon-invasive methods have been developed to induce plastic changes in the sensorimotor cortex. These rely on stimulating pairs of afferent nerves. By associative stimulation (AS) of two afferent nerves, excitability changes in the motor cortex occur as indicated by studies reporting changes in motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS). Repetitive stimulation of those nerves has a potential in rehabilitation and treatment of neurological disorders like stroke or spinal cord injury. Despite promising results and applications in human subjects using these methods, little is understood about the underlying basis for the changes which are seen. In the present study, behavioural, electrophysiological and immunohistochemical assessments were performed before and after paired associative and non-associative (NAS) median and ulnar nerve stimulation. Two macaque monkeys were trained to perform a skilled finger abduction task using refined behavioural methods. Monkeys were not able to move their thumb and index finger as selectively after one hour of paired AS as indicated by an increased number of errors and decreased performance measures. NAS however decreased error numbers and led to increased performances. Additionally, I recorded from identified pyramidal tract neurons and unidentified cells in primary motor cortex (M1), in two macaque monkeys before and after one hour of AS (and NAS) of the median and ulnar nerve. Cell discharge was recorded in response to electrical stimulation of each nerve independently. Some cells in M1 showed changed firing rates in response to nerve stimulation after AS (and NAS). Subsequently, structural changes in response to one week of paired AS were investigated. The laminar-specific density of parvalbumin-positive interneurons, perineuronal nets and the colocalisation of these two entities changed on the stimulated (in comparison to the non-stimulated) sensorimotor cortex. These findings suggest that the sensorimotor cortex undergoes plastic changes in response to AS (and NAS).Wellcome Trus

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 13th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2022, held in Hamburg, Germany, in May 2022. The 36 regular papers included in this book were carefully reviewed and selected from 129 submissions. They were organized in topical sections as follows: haptic science; haptic technology; and haptic applications

Toward a Better Understanding of Percussive Therapy and Pain

Despite the rapidly-increasing widespread adoption of percussive therapy as a tool for pain management by individual consumers and health professionals alike, relatively little experimental research has been done to clarify the neural mechanisms implicated in the many anecdotal stories of pain reduction. Inspired by an evidence-based theory of pain perception, according to which the brain’s anterior cingulate cortex processes both physically and emotionally painful inputs, it was hypothesized that the application of a physical stimulus—percussive therapy—would decrease socially-induced pain more readily than a vibration-removed control. Six conditions spread over three phases of testing were designed to specifically isolate the effect of vibration from other confounds, should such an effect exist. Instead, exploratory analyses revealed that participants in the pain induction conditions who received percussive therapy with or without vibration both reported significantly reduced pain. The mechanisms within percussive therapy beyond vibration that may have contributed to this finding, including touch and other social and cognitive factors, are discussed at length herein