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Humans shape their environment more than any other species does, and the environment, in turn, shapes the profile of human skills. In spite of the general specificity of practice of sensorimotor skills, the waxing and waning of specific skills goes along with modulations of a broader range of skills or sensorimotor abilities. This is illustrated by two examples. The first one is the death of handwriting, which is associated with a reduction of the quality of arm-hand motor control in the production of figural movements. The second one is the birth of video gaming, which facilitates performance in a variety of tasks, ranging from airplane piloting to laparoscopic surgery, probably because of improved control of attention, visual orientation, and further changes. These examples also illustrate the ambivalence of many technological changes that nourish social and educational controversies. [ABSTRACT FROM AUTHOR]

The last several years have seen a number of approaches to robot assistance of motor learning. Experimental studies have produced a range of findings from beneficial effects through null-effects to detrimental effects of robot assistance. In this review we seek an answer to the question under which conditions which outcomes should be expected. For this purpose we derive tentative predictions based on a classification of learning tasks in terms of the products of learning, the mechanisms involved, and the modulation of these mechanisms by robot assistance. Consistent with these predictions, the learning of dynamic features of trajectories is facilitated and the learning of kinematic and dynamic transformations is impeded by robotic guidance, whereas the learning of dynamic transformations can profit from robot assistance with error-amplifying forces. Deviating from the predictions, learning of spatial features of trajectories is impeded by haptic guidance, but can be facilitated by divergent force fields. The deviations point to the existence of additional effects of robot assistance beyond the modulation of learning mechanisms, e.g., the induction of a passive role of the motor system during practice with haptic guidance. [ABSTRACT FROM AUTHOR]

Standing postural control is known to be altered during aging, but age-related changes in sitting postural control have scarcely been explored. The present experiment studied the roles of visual and haptic information in a sitting task in both young and older adults. Fifteen young and fifteen older adults participated in this study. Six experimental conditions were performed with eyes open and eyes closed: quiet sitting, rocker-board sitting, and 4 conditions of haptic supplementation, provided by a hand-held pen, during rocker-board sitting. Classical variables were extracted from the center of pressure (COP) and pen trajectories, and the stabilogram diffusion analysis was performed on the COP data. Three-way ANOVAs (Group×Vision×Condition) were carried out. Postural instability was strongly attenuated by haptic supplementation in both age groups. Furthermore, instability due to visual deprivation was compensated by haptic supplementation. Long- and short-term diffusion coefficients were smaller in conditions of haptic supplementation. The present study confirmed the effect of haptic supplementation on both open-loop and closed-loop mechanisms of postural control and extended it to unstable sitting in young and older adults despite the complex biomechanical systems involved in sitting postural tasks. [ABSTRACT FROM AUTHOR]

Abstract: Discrimination of proprioceptive and visual spatial information is a prerequisite for the learning of visuo-motor transformations. This study investigated the individual''s capability to discriminate the directions of seen cursor motions and felt hand movements under a visuo-motor rotation paradigm and its age-related variation. Young and older participants performed 3-stroke arm movements on a digitizing tablet without seeing their arm. The visual feedback of the second stroke was rotated randomly by various angles ranging from −30° to 30° and displayed on a monitor. Older adults were poorer in discrimination than young adults. In both age groups, the felt hand direction was shifted toward the seen cursor direction (i.e., visual capture) by approximately 25% to 30% of the rotation of the visual feedback. Older adults also showed an enhanced visual capture. The results suggest that both the increased sensory noise and the increased assimilation of the bimodal information cause the reduction of discrimination capability in older adults. These findings provide underlying reasons for age-related changes in learning a new visuo-motor transformation. [Copyright &y& Elsevier]