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 patients had near-total loss of joint position, vibration, and discriminative touch sensation in the upper extremities. Muscle strength remained intact. 2. Subject...

1. Neurophysiological evidence that afferent information from skin receptors is important for proprioception has been gathered mainly in experiments relating to the human hand and finger joints. To investigate if proprioceptive information is also provided by skin mechanoreceptor afferents from skin areas related to large joints of postural importance, microneurography recordings were obtained ...

A pair of muscles powering the human joint in an antagonistic configuration exemplifies the main difference between standard industrial robots and biological motor systems. Since muscles have a natural stiffness that varies with the muscle activation level, the central nervous system (CNS) can generate stable equilibrium postures, towards which the arm is attracted, by properly regulating the a...

Elbow is a bone joint having a single axis and performing two movements: flexion and extension. Because this axis, passing through trochlea and humerus, is not perfectly transversal, but oriented from outside to inside, forward to backward and from up to low, during the two movements the forearm and the arm form an opened angle. Consequently, the complex movement guided around this axis suppose...

Proprioceptive afferents from muscle spindles encode information about peripheral joint movements for the central nervous system (CNS). The sensitivity of muscle spindle is nonlinearly dependent on the activation of gamma (γ) motoneurons in the spinal cord that receives inputs from the motor cortex. How fusimotor control of spindle sensitivity affects proprioceptive coding of joint position is ...

Most of research projects on cyclical motor activity focus on locomotion. They provide ambivalent data on the considered theme. Saito et al. [1] present the results of their research on the relationship between step length and frequency in sprint, which was not a decreasing one. Laurent and Pailhous [2] observed that step length and frequency both correlate with walking speed but are relatively...

We studied the stability of changes in motor performance associated with adaptation to a novel dynamic environment during goal-directed movements of the dominant arm. Eleven normal, human subjects made targeted reaching movements in the horizontal plane while holding the handle of a two-joint robotic manipulator. This robot was programmed to generate a novel viscous force field that perturbed t...