Learn More
OBJECTIVE To examine the correlation between rigidity and interaction of stretch reflex and shortening reaction during passive movements of the wrist and to compare this correlation with that between rigidity and stretch reflex alone. METHODS Twelve subjects with Parkinson's disease participated in the study in Off-medication and On-medication states. A(More)
Phase-dependent and task-dependent modulation of reflexes has been extensively demonstrated in leg muscles during locomotory activity. In contrast, the modulation of reflex responses of hand muscles during rhythmic movement is poorly documented. The objective of this study was to determine whether comparable reflex modulation occurs in muscles controlling(More)
OBJECTIVE Quantify the enhancement of parkinsonian rigidity associated with a contralateral activation maneuver. METHODS Twelve subjects with PD and eight controls participated in the study protocol. Subjects' tested hand was displaced by a servo-motor throughout wrist flexion and extension motions of 60° without and with a concurrent gripping activation(More)
Rigidity in Parkinson’s disease (PD) is defined as an increased resistance to passive movement of a joint. The plastic-type rigidity is uniform and constant throughout the entire range of motion, whereas the cogwheel-type rigidity is accompanied by tremor. Rigidity in PD has been understudied. Thus, its pathophysiological basis remains unclear. The purpose(More)
OBJECTIVE To test a hypothesis that Parkinsonian rigidity is more pronounced in imposed extension than flexion movement. METHODS Twelve Parkinsonian subjects (both "Off" and "On" medication states) and seven control subjects participated in the protocol, in which a servomotor imposed wrist flexion and extension. Rigidity was quantitatively evaluated by(More)
STUDY DESIGN Electromyographic study in complete and incomplete spinal cord injury (SCI). OBJECTIVE To examine the changes in the pattern of reciprocal inhibition between agonist and antagonist muscles in SCI. SETTINGS Sensory Motor Performance Program, Rehabilitation Institute of Chicago, IL, USA. METHODS Tendon taps were delivered manually with an(More)
The strategy of human manual control is investigated in balancing an inverted pendulum under time-delay constraints. Experiments show that as the task becomes more difficult due to the increase in time delay, the human operator adopts a more discrete-like strategy. Interpretation of the discrete-control mechanism is provided by relating the observed human(More)
Parkinson’s disease (PD) is a chronic progressive neurodegenerative disease that is clinically manifested by a triad of cardinal motor symptoms — rigidity, bradykinesia and tremor — due to loss of dopaminergic neurons. The motor symptoms of PD become progressively worse as the disease advances. PD is also a heterogeneous disease since rigidity and(More)
OBJECTIVE Quantify the effects of increased amplitude and rate of muscle stretch on parkinsonian rigidity. METHODS Eighteen subjects with Parkinson's disease participated in this study. Subjects' tested hand was passively displaced through 60° and 90° ranges of wrist flexion and extension at velocities of 50°/s and 280°/s in both treated and untreated(More)