1. We recently showed that patients lacking proprioceptive input from their limbs have particular difficulty performing multijoint movements. In a pantomimed slicing gesture requiring sharp reversals in hand path direction, large distortions at movement because of failure to coordinate the timing separate shoulder and elbow joints. hypothesized these reversal errors resulted uncompensated effects inertial interactions produced by changes joint acceleration were transferred elbow. now test...

1. We analyzed the performance of a simple pantomimed gesture in 2 patients with large-fiber sensory neuropathy and 11 control subjects to determine how proprioceptive deafferentation disrupts unconstrained multijoint movements. Both had near-total loss joint position, vibration, discriminative touch sensation upper extremities. Muscle strength remained intact. 2. Subjects performed similar slicing loaf bread. In this gesture, hand first moves outward from body, reverses direction sharply,...

This study compares the coordination patterns employed for left and right arms during rapid targeted reaching movements. Six right-handed subjects reached to each of three targets, designed elicit progressively greater amplitude interaction torques at elbow joint. All targets required same excursion (20°), but different shoulder excursions (5, 10, 15°, respectively). Movements were restricted supported on a horizontal plane by frictionless air-jet system. Subjects received visual feedback...

Recent findings from our laboratory suggest that a major factor distinguishing dominant nondominant arm performance is the ability by which effects of intersegmental dynamics are controlled CNS. These studies indicated reliably used more torque-efficient patterns for movements made with similar speeds and accuracy than movements. Whereas, hand-path curvatures systematically varied amplitude interaction torques transferred between segments moving limb, did not. However, previous not...

Intersegmental dynamics are controlled by sequential anticipatory, error correction, and positional control mechanisms. The purpose of this study is to examine the mechanisms underlying intersegmental during reaching movements. Two experiments were conducted determine relative contributions anticipatory somatosensory feedback in controlling whether adaptation novel generalizes across a range movement directions. used interaction torques examined altering inertial load forearm. Movements...

Recent reports of functional impairment in the 'unaffected' limb stroke patients have suggested that these deficits vary with side lesion. This not only supports idea ipsilateral hemisphere contributes to arm movements, but also implies such contributions are lateralized. We previously left and right hemispheres specialized for controlling different features movement. In reaching non-dominant appears better adapted achieving accurate final positions dominant specifying initial trajectory...

This study was designed to examine interlimb asymmetries in responding unpredictable changes inertial loads, which have implications for our understanding of the neural mechanisms underlying handedness. Subjects made repetitive single joint speed constrained 20 degrees elbow flexion movements, while arm supported on a horizontal, frictionless, air-jet system. On random trials, 2-kg mass attached splint prior "go" signal. were not given explicit information about movement nor they able view...

This paper reviews a series of experiments comparing intact controls with functionally deafferented patients to determine the role proprioception in controlling dynamic interactions between limb segments during movement. We examine control hand path planar movement-reversal task and familiar three-dimensional gesture similar biomechanical characteristics. In subjects had move their out back along straight-line horizontal plane without visual feedback. The lengths directions target line were...

We have proposed a model of motor lateralization, in which the left and right hemispheres are specialized for different aspects control: hemisphere predicting accounting limb dynamics stabilizing position through impedance control mechanisms. Our previous studies, demonstrating deficits ipsilesional arm stroke patients with or damage, provided critical test our model. However, after most prominent on contralesional side. Post-stroke rehabilitation has also, naturally, focused improving...

The question addressed in this study is whether parietal brain circuits involved adaptation to novel visuomotor conditions are lateralized. This information critical for characterizing the neural mechanisms mediating adaptive behavior humans, as well assessing effects of unilateral damage on function. Moreover, previous research has been controversial regard. We compared 10 patients with focal, unilateral, left or right lesions and healthy control participants. All subjects reached each...

In this study, we examine whether corrections made during an ongoing movement are differentially affected by left hemisphere damage (LHD) and right (RHD). Our hypothesis of motor lateralization proposes that control mechanisms specialized to the rely largely on online processes, while primarily utilizes predictive specify optimal coordination patterns. We therefore predict RHD, but not LHD, should impair correction when task goals unexpectedly changed. Fourteen stroke subjects (7 7 RHD) 14...

Motor lateralization in humans has primarily been characterized as "handedness", resulting the view that one arm-hemisphere system is specialized for all aspects of movement while other simply a weaker analogue. We have proposed an alternative motor reflects proficiency each arm complementary functions arises from specialization hemisphere distinct control mechanisms. However, before this idea hemispheric can be accepted, it necessary to precisely identify these distinct, lateralized Here we...

Handedness is a pronounced feature of human motor behavior, yet the underlying neural mechanisms remain unclear. We hypothesize that lateralization results from asymmetries in predictive control task dynamics and limb impedance. To test this hypothesis, we present an experiment with two different force field environments, predictable magnitude varies square velocity, less linearly velocity. These fields were designed to be compatible controllers are specialized predicting dynamics,...

Mechanisms underlying interlimb transfer of adaptation to visuomotor rotations have recently been explored in depth. However, little data are available regarding novel inertial dynamics. The present study thus investigated dynamics by examining the effect initial training with one arm on subsequent performance other a 1.5-kg mass attached eccentrically forearm. Using inverse dynamic analysis, we examined changes torque strategies associated extra mass, and that adaptation. Following dominant...

In the absence of visual feedback, subject reports hand location tend to drift over time. Such has been attributed a gradual reduction in usefulness proprioception signal limb position. If this account is correct, should degrade accuracy movement distance and direction series movements made without feedback. To test hypothesis, we asked participants perform six 75 repetitive from visible start target, time with regular, audible tone. Fingertip position feedback was given by cursor during...

The current study was designed to examine potential interlimb asymmetries in controlling movement extent. Subjects made repetitive single-joint elbow extension movements while the arm supported on a horizontal, frictionless, air-jet system. Four targets of 10, 20, 35, and 45 degrees excursions were randomly presented over course 150 trials. For both arms, peak tangential hand velocity scaled linearly with distance. There no significant difference between either velocities or accuracies for...