Secondary endings of muscle spindles: Structure, reflex action, role in motor control and proprioception.

New Findings: What is the topic of this review? We describe the structure and function of secondary sensory endings of muscle spindles, their reflex action and role in motor control and proprioception. What advances does it highlight? In most mammalian skeletal muscles, secondary endings of spindles are more or much more numerous than primary endings but are much less well studied. By focusing on secondary endings in this review, we aim to redress the balance, draw attention to what is not known and stimulate future research.

Motor Neuroprostheses.

Neuroprostheses (NPs) are electrical stimulators that activate nerves, either to provide sensory input to the central nervous system (sensory NPs), or to activate muscles (motor NPs: MNPs). The first MNPs were belts with inbuilt batteries and electrodes developed in the 1850s to exercise the abdominal muscles. They became enormously popular among the general public, but as a result of exaggerated therapeutic claims they were soon discredited by the medical community.

Neurophysiology and neural engineering: a review.

Neurophysiology is the branch of physiology concerned with understanding the function of neural systems. Neural engineering (also known as neuroengineering) is a discipline within biomedical engineering that uses engineering techniques to understand, repair, replace, enhance, or otherwise exploit the properties and functions of neural systems. In most cases neural engineering involves the development of an interface between electronic devices and living neural tissue.

Sensory control of normal movement and of movement aided by neural prostheses.

Signals from sensory receptors in muscles and skin enter the central nervous system (CNS), where they contribute to kinaesthesia and the generation of motor commands. Many lines of evidence indicate that sensory input from skin receptors, muscle spindles and Golgi tendon organs play the predominant role in this regard. Yet in spite of over 100 years of research on this topic, some quite fundamental questions remain unresolved.

Tele-Supervised FES-Assisted Exercise for Hemiplegic Upper Limb.

Unlabelled: Stroke survivors often have upper limb (UL) hemiparesis, limiting their ability to perform activities of daily life (ADLs). Intensive, task-oriented exercise therapy (ET) can improve UL function, but motivation to perform sufficient ET is difficult to maintain. Here, we report on a trial in which a workstation was deployed in the homes of chronic stroke survivors to enable tele-coaching of ET in the guise of computer games.

A fully automated, quantitative test of upper limb function.

The Rehabilitation Joystick for Computerized Exercise (ReJoyce, Rehabtronics Inc., Edmonton, Alberta, Canada), is a workstation on which participants exercise dexterous movement tasks in the guise of computer games. The system incorporates the ReJoyce Arm and Hand Function Test (RAHFT).

Controlled nerve ablation with direct current: parameters and mechanisms.

Spastic hypertonus (muscle over-activity) often develops after spinal cord injury or stroke. Chemodenervating agents such as Botulinum toxin A (BtA) and phenol are often used to treat this condition. We have previously shown that the use of direct current (DC) to create controlled lesions of peripheral nerves may provide a means of reducing spastic hypertonus.

Sensory systems in the control of movement.

Animal movement is immensely varied, from the simplest reflexive responses to the most complex, dexterous voluntary tasks. Here, we focus on the control of movement in mammals, including humans. First, the sensory inputs most closely implicated in controlling movement are reviewed, with a focus on somatosensory receptors.

First permanent human implant of the Stimulus Router System, a novel neuroprosthesis: preliminary testing of a polarity reversing stimulation technique.

Neuroprostheses (NPs) are electrical stimulators that help to restore sensory or motor functions lost as a result of neural damage. The Stimulus Router System (SRS) is a new type of NP developed in our laboratory. The system uses fully implanted, passive leads to "capture" and "route" some of the current flowing between pairs of surface electrodes to the vicinity of the target nerves, hence eliminating the need for an implanted stimulator.

First permanent implant of nerve stimulation leads activated by surface electrodes, enabling hand grasp and release: the stimulus router neuroprosthesis.

Background: . More than 150 000 neuroprostheses (NPs) have been implanted in people to restore bodily function in a variety of neural disorders. The authors developed a novel NP, the Stimulus Router System (SRS), in which only passive leads are implanted.

Technology improves upper extremity rehabilitation.

Stroke survivors with hemiparesis and spinal cord injury (SCI) survivors with tetraplegia find it difficult or impossible to perform many activities of daily life. There is growing evidence that intensive exercise therapy, especially when supplemented with functional electrical stimulation (FES), can improve upper extremity function, but delivering the treatment can be costly, particularly after recipients leave rehabilitation facilities. Recently, there has been a growing level of interest among researchers and healthcare policymakers to deliver upper extremity treatments to people in their homes using in-home teletherapy (IHT).

In-home tele-rehabilitation improves tetraplegic hand function.

Background: Spinal cord injury (SCI) survivors with tetraplegia have great difficulty performing activities of daily living (ADLs). Functional electrical stimulation (FES) combined with exercise therapy (ET) can improve hand function, but delivering the treatment is problematic.

Objective: To compare 2 ET treatments delivered by in-home tele-therapy (IHT).

Nerve lesioning with direct current.

Spastic hypertonus (muscle over-activity due to exaggerated stretch reflexes) often develops in people with stroke, cerebral palsy, multiple sclerosis and spinal cord injury. Lesioning of nerves, e.g.

Properties of the stimulus router system, a novel neural prosthesis.

Various types of neural prostheses (NPs) have been developed to restore motor function after neural injury. Surface NPs are noninvasive and inexpensive, but are often poorly selective, activating nontargeted muscles and cutaneous sensory nerves that can cause discomfort or pain. Implantable NPs are highly selective, but invasive and costly.

Evaluation of tooth-click triggering and speech recognition in assistive technology for computer access.

Background: Computer access can play an important role in employment and leisure activities following spinal cord injury. The authors' prior work has shown that a tooth-click detecting device, when paired with an optical head mouse, may be used by people with tetraplegia for controlling cursor movement and mouse button clicks.

Objective: To compare the efficacy of tooth clicks to speech recognition and that of an optical head mouse to a gyrometer head mouse for cursor and mouse button control of a computer.

Transcutaneously coupled, high-frequency electrical stimulation of the pudendal nerve blocks external urethral sphincter contractions.

Background: Detrusor-sphincter dyssynergia is a condition in which reflexive contractions of the external urethral sphincter occur during bladder contractions, preventing the expulsion of urine. High-frequency stimulation (kHz range) has been shown to elicit a fast-acting and reversible block of action potential propagation in peripheral nerves, which may be a useful technique in the management of this condition.

Objective: The aim of these experiments was to see if a newly developed stimulus delivery system, capable of transmitting current transcutaneously to remote peripheral nerves using a passive implanted conductor, was an effective way to transmit high-frequency waveforms to the pudendal nerve to block ongoing sphincter contractions.

Tooth-click control of a hands-free computer interface.

People with severe upper limb paralysis use devices that monitor head movements to control computer cursors. The three most common methods for producing mouse button clicks are dwell-time, sip-and-puff control, and voice-recognition. Here, we tested a new method in which small tooth-clicks were detected by an accelerometer contacting the side of the head.

The neuromechanical tuning hypothesis.

Simulations performed with neuromechanical models are providing insight into the neural control of locomotion that would be hard if not impossible to obtain in any other way. We first discuss the known properties of the neural mechanisms controlling locomotion, with a focus on mammalian systems. The rhythm-generating properties of central pattern generators (CPGs) are discussed in light of results indicating that cycle characteristics may be preset by tonic drive to spinal interneuronal networks.

Predictive and reactive tuning of the locomotor CPG.

The neural control of locomotion involves a constant interplay between the actions of a central pattern generator (CPG) and sensory input elicited by bodily movement. With respect to the CPG, recent analysis of fictive locomotion has shown that durations of flexion and extension tend to covary along specific lines in plots of phase duration versus cycle duration. The slopes of these lines evidently depend on internal states that vary among preparations, but, within a preparation, remain rather steady from one sequence to the next.

Upper-extremity functional electric stimulation-assisted exercises on a workstation in the subacute phase of stroke recovery.

Objective: To test the efficacy of functional electric stimulation (FES)-assisted exercise therapy (FES-ET) on a workstation in the subacute phase of recovery from a stroke.

Design: Single-blind, randomly controlled comparison of high- and low-intensity treatment.

Setting: Laboratory in a rehabilitation hospital.

A new means of transcutaneous coupling for neural prostheses.

Neural prostheses are electronic stimulators that activate nerves to restore sensory or motor functions. Implanted neural prostheses receive command signals and in some cases energy to recharge their batteries through the skin by telemetry. Here, we describe a new approach that eliminates the implanted stimulator.

Intraspinal stimulation caudal to spinal cord transections in rats. Testing the propriospinal hypothesis.

Many laboratories have reported the successful regeneration of neurons across damaged portions of the spinal cord. Associated improvements in hindlimb locomotor movements have been attributed to the formation of functional neuronal connections with the locomotor central pattern generator (CPG). However, regenerating axons generally extend no more than 10 mm caudal to the lesion sites, terminating about 20 mm short of the lumbar segments thought to contain the CPG.

Decoding sensory feedback from firing rates of afferent ensembles recorded in cat dorsal root ganglia in normal locomotion.

Sensory feedback is required by biological motor control systems to maintain stability, respond to perturbations, and adapt. Similarly, motor neuroprostheses require feedback to provide natural and complete restoration of motor functions. In this paper, we show that ensemble firing rates from the body's mechanoreceptors can provide a natural source of kinematic state feedback and could be useful for prosthetic control.

Control of urinary bladder function with devices: successes and failures.

The management of urinary tract dysfunction is crucial for the health and well-being of people with spinal cord injury. Devices, specifically catheters, play an important role in the daily regime of bladder management for most people with spinal cord injury. However, the high incidence of complications associated with the use of catheters, and the fact that the spinal segments involved in lower urinary tract control remain intact in most cord-injured people, continue to motivate research into devices that could harness the nervous system to provide greater control over lower urinary tract function.