Learn More
It is known that the springlike properties of muscles provide automatic load compensation during weight bearing. How crucial is sensory control of the motor output given these basic properties of the locomotor system? To address this question, a neuromuscular model was used to test two hypotheses. (1) Stretch reflexes are too weak and too delayed to(More)
Psychophysical studies have reported an overestimation of limb position in the direction of movement during the early part of active movements. The main hypothesis tested in this study is that the overestimation results from a process of forward prediction of limb state driven by an efference copy of the outgoing motor command. This hypothesis predicts that(More)
Online control of movement requires complex integration of predictive central feedforward and peripheral sensory feedback signals. We studied the hand trajectories of human subjects pointing to visual targets that abruptly changed locations by different amounts and modeled the mechanism of rapid online correction using a dynamic model of a two-joint limb.(More)
The aim of this study was to investigate how humans correct ongoing arm movements while standing. Specifically, we sought to understand whether the postural adjustments in the legs required for online corrections of arm movements are predictive or rely on feedback from the moving limb. To answer this question we measured online corrections in arm and leg(More)
Reaching movements to visual targets are under fast feedback control, which can rapidly correct an ongoing movement for errors. This study investigates how this online correction is affected by the application of a new visuomotor transformation. Thirty-two subjects made planar pointing movements to visual targets. Vision of the arm was prevented, and hand(More)
OBJECTIVE To test a functional electric stimulation (FES)-assisted exercise therapy system for improvement of motor function of the hemiplegic upper extremity. DESIGN A before-after trial, with 2-month follow-up. SETTING A university research laboratory. PARTICIPANTS A convenience sample of 6 subjects (3 men, 3 women). Main inclusion criteria were(More)
In the absence of sensory input, the central nervous system can generate a rhythmical pattern of coordinated activation of limb muscles. Contracting muscles have spring-like properties. If synergistic muscles are co-activated in the right way, sustained locomotion can occur. What is the role of sensory input in this scheme? In this chapter we first discuss(More)
To make an accurate movement, the CNS has to overcome the inherent complexities of the multijoint limb. For example, interaction torques arise when motion of individual arm segments propagates to adjacent segments causing their movement without any muscle contractions. Since these passive joint torques significantly add to the overall torques generated by(More)
Current diagnosis and treatment of movement impairment post-stroke is based on the subjective assessment of select movements by a trained clinical specialist. However, modern low-cost motion capture technology allows for the development of automated quantitative assessment of motor impairment. Such outcome measures are crucial for advancing post-stroke(More)
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. PARTICIPANTS Nineteen stroke survivors(More)