Usability of a visual feedback system to assess and improve movement disorders related to neck pain: Perceptions of physical therapists and patients.

A prototype visual feedback system has been developed to assess and improve movement disorders related to neck pain. The aim of this study was to assess the usability of the prototype in a rehabilitation setting. Twelve physical therapists integrated the device into their regular therapy programs for 24 neck pain patients with movement disorders. Each patient performed three individual therapy sessions with the device under physical therapist supervision. Usability was assessed by the physical therapists and patients using therapy diaries, the System Usability Scale, and focus group or personal interviews. Based on an overall usability rating of marginally acceptable, the visual feedback system was generally found to be a device with the potential to assess and train neck pain patients but needs improvement. To become a useful adjunct to regular physical therapy, improvements in the hardware and software, and further system developments are required.

Modulation of locomotor activity in complete spinal cord injury.

The aim of this study was to evaluate the modulation of muscle activity during locomotor-like movements by different walking speeds in subjects with a motor complete spinal cord injury (SCI) compared to actively--and passively-walking control subjects without neurological deficit. Stepping movements on a treadmill were induced and assisted by a driven gait orthosis. Electromyographic (EMG) muscle activity of one leg (rectus and biceps femoris, tibialis anterior and gastrocnemius) was recorded and analyzed at three stepping velocities with similar body weight support in both subject groups. In SCI subjects, the EMG amplitude of biceps femoris, tibialis anterior and gastrocnemius was in general similar or weaker than in passively- and actively-stepping control subjects, but that of rectus femoris was larger. The degree of co-activation between tibialis anterior and gastrocnemius was higher in SCI than in control subjects. A significant velocity-dependent EMG modulation was present in all four-leg muscles in both subject groups. In SCI subjects, this EMG modulation was similar to that in actively stepping control subjects. It is concluded that in complete spastic SCI subjects, spinal neuronal circuits underlying locomotion can to a large extent adequately respond to a change in external drive to adapt the neuronal pattern to a new locomotion speed. The application of various speeds might enhance the effect of locomotor training in incomplete SCI subjects.

Cooperative strategies for robot-aided gait neuro-rehabilitation.

Task-oriented repetitive movements can improve muscular strength and movement coordination in patients with impairments due to neurological or orthopedic lesions. The application of robotics and automation technology can serve to assist, enhance, evaluate, and document neurological and orthopedic rehabilitation of the lower and upper extremities. This review presentation will give an overview of patient-cooperative techniques to the robot-aided gait rehabilitation of paralyzed patients. Patient-cooperative means that the technical system considers the patient intention and efforts rather than imposing any predefined movement or inflexible strategy. It is hypothesized that cooperative approaches have the potential to improve the therapeutic outcome compared to classical rehabilitation strategies. Three new cooperative strategies are presented in this review. In all three strategies the patient's movement effort is detected and processed in three different ways. First, the data is used to offer the patient an increased freedom of movement by a certain amount of robot compliance. Second, the robot behavior is adapted to the patient movement efforts. In the third strategy the recorded movement data are displayed to the patient in order to improve the patient efforts by biofeedback principles.

Biofeedback in gait training with the robotic orthosis Lokomat.

Neurological diseases - such as spinal cord injury, stroke and traumatic brain injury - frequently result in gait impairment The recovery of the walking ability requires functional training (i.e. walking), as previous research in man and animal has shown. Because the patient usually has reduced voluntary muscle force early after the incident, his/her movements require external support by physical therapists or special robotic devices. The Lokomat is a robotic gait orthosis with electromechanical drives that supports walking on a treadmill with body weight support. Because the movements are performed according to a predefined trajectory, there is no visible cue to the amount the patient is contributing. However, the forces measured within the drives can deliver an estimation of this contribution. Based on these measurements, biofeedback on the patient's gait performance was added as a new feature. The visual display will allow the patient to get direct feedback on his/her efforts, and will allow the therapist to instruct the patient better. We report here that the biofeedback can correctly reflect the activity of a healthy subject, that patients can benefit from the use, and what the patients' opinion is.

A possible role of the superior colliculus in eye-hand coordination.

Reaching with the arm to a newly appearing target is usually preceded by a saccadic eye movement. Neurons in the superior colliculus (SC) constitute one important brain structure controlling saccades. Yet, the SC also contains reach neurons activated during arm movements, whose location extends also deeper into the underlying mesencephalic reticular formation. Reach neurons can be divided into two classes based on their different modulation with respect to gaze position. For the first class, the gaze-independent reach neurons, the activity does not depend on which location is currently fixated, but solely on the position and movement of the (usually contralateral) arm. There is a correlation of the activity of these neurons with the activity of shoulder muscles. The second class, the gaze-related reach neurons, are active for reaches into a specific area relative to the current point of gaze. This means the target has to project on a certain part of the retina, while it is not important which arm is used or by which trajectory the target will be reached. Many fixation neurons in the rostral pole of the SC discharge tonically during fixation and pause during saccades. For some fixation neurons, the activity can be increased during simultaneous arm movements, for others decreased. Two psychophysical experiments with healthy human subjects show possible behavioral correlates of an interaction between these reach neurons and visuomotor neurons within the SC.

Influence of arm movements on saccades in humans.

When reaching for an object we usually look at it before we touch it with the hand. This often unconscious eye movement prior to the arm movement allows guiding of the final part of the hand trajectory by visual feedback. We examined the temporal and spatial coordination of this control system by psychophysical measurements of eye and arm movements of naive human subjects looking or looking and pointing as fast as possible to visual targets in physical and virtual-reality setups. The reaction times of saccades to a step-displaced target were reduced, and the number of corrective saccades decreased, when the subject had to produce a corresponding simultaneous hand movement to the same target. The saccadic reaction time was increased when saccade and hand movement went in opposite directions. In a double-step task the reaction time for the second saccade was longer than for the first. Co-use of the hand leads to an additional increase of saccadic reaction time. Taken together this study shows an improvement in initial saccades if they are accompanied by hand movements to the same target. This effect might ensure that the reach target is foveated early and accurately enough to support the visual feedback control of the hand near the target. Longer reaction times for the second saccade to double-step displaced targets might reflect a saccadic refractory time intensified by simultaneous arm movements. These results are discussed in the light of recent findings from our laboratory on saccade- and reach-related neurons in the superior colliculus of macaque monkeys.