For several decades of years, the electrical stimulation has been applied on rehabilitation of motional recovery for quadriplegic and paraplegic patients such as walking, standing, and cycling exercise. As the advancement of VLSI (very large scale integration) technology, the implantable micro-stimulators become feasible in recent years. This thesis presents an implantable system including an inductively coupling transceiver of power & data, a protocol of communication, and the implementation of a FES (Functional Electrical Stimulation ) SOC (System-On-chip). The first part of this thesis discusses the architecture of the proposed implantable FES system, including the theory of wireless power transmission, the implementation of mixed-signal circuits, the RS232 protocol, and two encoding methods of Manchester code and NRZ code. The second part of this thesis is focused on the multi-frequency stimulation of the implantable FES system, which comprises an advanced communication protocol suitable for multi-frequency stimulation function and a novel arrangement of interconnections for the chip.

Electrical stimulation has been a controversial treatment option for acquired dysphagia since the initial study by Freed, Freed, Chatburn, and Christian (2001). This report investigates the efficacy of electrical stimulation by addressing three issues related to the use of this technique: 1) the movement of the hyolaryngeal complex during stimulation, 2) the population(s) for which electrical stimulation is efficacious, and 3) the necessity of combining electrical stimulation with traditional treatments for the treatment to be effective. Twenty-two studies were evaluated and revealed overall positive findings for the use of electrical stimulation as a treatment technique. To further analyze the strength of these findings, the studies were evaluated for methodological limitations with regards to participant selection, treatment design, and outcome measure selection. This analysis revealed two main methodological limitations: 1) a lack of established treatment protocol which led to differences in how and with what other techniques electrical stimulation was used and 2) an absence of follow-up measures. While these factors do not appear to affect the applicability of the study findings, future research should focus developing a treatment protocol and investigating the long-term benefits of electrical stimulation treatment. / text

Electrical potentials are the fundamental currency of communication in the nervous system. The advanced executive functions of the prefrontal cortex and the motor commands delivered to the neuromuscular junction, though involved with very different aspects of behavior, both rely on time-varying electrical signals. It is possible to "listen to" the internal communications of the nervous system by measuring the electrical potentials in the extra-cellular space. However, this is only meaningful if there is some way to interpret these signals, which are incredibly complicated and information rich. This dissertation represents an attempt to decode some of these signals in order to reveal their significance for behavior and function. The first study is an investigation of the relationship between different elements of the local field potential in the prefrontal cortex and memory consolidation. It is shown that certain electrographic signatures of non-rapid eye movement sleep, namely K-complexes and low-voltage spindles, are correlated with neuronal replay of recent experiences. It is also shown that the global fluctuations of activity in the population of cells, known as up/down states, is correlated with neuronal replay. Finally, it is shown that high-voltage spindles are not correlated with memory replay, and are therefore functionally different from low-voltage spindles. The second study focuses on the relationship between movements of the upper limb and the coordinated neural control, as measured by the electromyogram (EMG), of the muscles generating that movement. We show that different probability-based models can be used to predict what the pattern of EMG in the different muscles will be for any given kinematic state of the hand. In the third study it is demonstrated that the kinematic output associated with a particular pattern of EMG can be reproduced with electrical stimulation. Thus, it is not only possible to understand the commands issued by the nervous system, it is also possible to issue commands by interfacing with the nervous system directly. Finally, the design for an experiment that would combine EMG prediction with translation of EMG into electrical stimulus patterns is presented. The objective of this study would be to use these methods to fully control the upper limb in a way that would be useful for a functional electrical stimulation-based neuroprosthetic for spinal cord injured patients.

Functional electrical stimulation (FES) systems have been developed to help restore various neuromuscular functions in individuals with neurological disorders leading to paralysis. Most of the current FES systems are designed for specific neuroprosthesis applications (i.e., walking, grasping, bladder voiding, coughing, etc.) and when one intends to use them in other custom made applications they are very limited due to a lack of functionality and flexibility in hardware and programmability. This prevents effective and efficient development of customized neuroprostheses. Research and development efforts at the Rehabilitation Engineering Laboratory at the University of Toronto were being carried out with an objective to produce a new, fully programmable and portable FES system. This thesis presents a novel proof-of-concept prototype controller for use in the new FES system. The controller subsystem manages and controls the overall FES system including the real-time decoding and execution of stimulation, data acquisition, external systems interfaces and user interface.

Recovery of the ability to maintain balance during standing is one of the primary and essential goals of rehabilitation programs for individuals with Spinal Cord Injury (SCI). Regaining functionality during standing by means of a neuroprosthesis would decrease secondary complications and increase independence, and would consequently improve the quality of life of these individuals. However, the development of a standing neuro- prosthesis requires techniques to generate reliable and predictable torque vectors in the lower limbs. We proposed and tested a method based on surface Functional Electrical Stimulation (FES) and the idea that three independent muscles can form a basis that would span the joint torque vector space. We tested the proposed stimulation technique on the quadriceps muscles that produce knee extension. The results of this study suggest that the quadriceps muscle basis vectors are insufficient to cover the knee joint vector space.

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Functional electrical stimulation (FES) systems have been developed to help restore various neuromuscular functions in individuals with neurological disorders leading to paralysis. Most of the current FES systems are designed for specific neuroprosthesis applications (i.e., walking, grasping, bladder voiding, coughing, etc.) and when one intends to use them in other custom made applications they are very limited due to a lack of functionality and flexibility in hardware and programmability. This prevents effective and efficient development of customized neuroprostheses. Research and development efforts at the Rehabilitation Engineering Laboratory at the University of Toronto were being carried out with an objective to produce a new, fully programmable and portable FES system. This thesis presents a novel proof-of-concept prototype controller for use in the new FES system. The controller subsystem manages and controls the overall FES system including the real-time decoding and execution of stimulation, data acquisition, external systems interfaces and user interface.

Recovery of the ability to maintain balance during standing is one of the primary and essential goals of rehabilitation programs for individuals with Spinal Cord Injury (SCI). Regaining functionality during standing by means of a neuroprosthesis would decrease secondary complications and increase independence, and would consequently improve the quality of life of these individuals. However, the development of a standing neuro- prosthesis requires techniques to generate reliable and predictable torque vectors in the lower limbs. We proposed and tested a method based on surface Functional Electrical Stimulation (FES) and the idea that three independent muscles can form a basis that would span the joint torque vector space. We tested the proposed stimulation technique on the quadriceps muscles that produce knee extension. The results of this study suggest that the quadriceps muscle basis vectors are insufficient to cover the knee joint vector space.

Neuromuscular electrical stimulation (NMES) is a common therapeutic tool for persons with movement disorders. The manner in which NMES generates muscular contractions has traditionally been attributed to the depolarization of motor axons underneath the stimulating electrodes, a purely peripheral mechanism, which does not involve the central nervous system (CNS). During NMES however, sensory axons are also recruited, initiating an afferent volley which can affect both spinal and cortical centers. This thesis is focused on identifying how this afferent volley influences NMES-evoked contractions and CNS excitability. Four projects are described in which NMES was delivered to generate plantar-flexion contractions. The first goal was to establish the influence of stimulus pulse width on the central recruitment of motoneurons. Contrary to previous findings, changing the pulse width did not significantly alter maximal soleus H-reflex amplitudes; however, wider pulses resulted in a leftward shift of the H-reflex recruitment curve and increased H-reflex amplitudes on the ascending limb of the recruitment curve. The second goal was to examine the effect of stimulus pulse-width on electromyograpic responses and torque during NMES. During 20 Hz NMES, wide pulse widths depressed motor-waves (M-waves) and enhanced H-reflexes, generating larger contractions with a relatively greater central contribution, than when narrow pulses were used. The third project compared the torque produced during NMES-evoked contractions before and during a complete anesthetic block of the tibial and common peroneal nerves. Results from this project showed that contractions arising from a combination of central and peripheral mechanisms fatigue less than contractions that develop from the recruitment of motor axons alone. The final project investigated how spinal and corticospinal excitability associated with the soleus muscles are affected following NMES, voluntary contractions, or a combination of both. It was found that a combination of voluntary contractions and electrical stimulation induced plastic changes in the spinal circuitry of the stimulated muscle without affecting cortical circuitry or inducing any contralateral effects. Collectively, these experiments highlight that wider pulse widths induce a greater reflexive recruitment of motoneurons which contributes to the evoked torque during NMES, and that the evoked afferent volley reduces fatigue and influences spinal circuitry plasticity in the plantar-flexors. Methods to enhance the afferent volley during NMES are only beginning to be tested in clinical populations and future experiments will determine the potential efficacy for persons with movement disorders. / Neuroscience

AIM The aim of this study was to identify the immediate effects on cortical excitability and grip control of a short intervention of EMG-triggered neuromuscular electrical stimulation, compared to voluntary activation of the finger flexor muscles, in people with chronic stroke. STUDY DESIGN This experimental study used a within-subject design with experimental and control interventions. PARTICIPANTS Fifteen people with chronic stroke participated in the study. INTERVENTION Participants performed a simple force tracking task with or without EMG-triggered neuromuscular electrical stimulation of the finger flexor muscles. MAIN OUTCOME MEASURES Cortical excitability was measured by single and paired-pulse transcranial magnetic stimulation. Multi-digit grip control accuracy was measured during ramp and sine wave force tracking tasks. Maximal grip strength was measured before and after each intervention to monitor muscle fatigue. RESULTS No significant increases in cortico-motor excitability were found. Intracortical inhibition significantly increased following the EMG-triggered neuromuscular electrical stimulation intervention immediately post-intervention (t = 2.466, p = .036), and at 10 minutes post-intervention (t = 2.45, p = .04). Accuracy during one component of the force tracking tasks significantly improved (F(1, 14) = 4.701, p = .048), following both EMG-triggered neuromuscular electrical stimulation and voluntary activation interventions. Maximal grip strength reduced significantly following both interventions, after the assessment of cortical excitability (F(1, 8) = 9.197, p = .16), and grip control (F(1, 14) = 9.026, p = .009). CONCLUSIONS EMG-triggered neuromuscular electrical stimulation during short duration force tracking training does not increase cortical excitability in participants with chronic stroke. Short duration force tracking training both with and without EMG-triggered neuromuscular electrical stimulation leads to improvements in training-specific aspects of grip control in people with chronic stroke.