Wrist Position Sense in Two Dimensions: Between-Hand Symmetry and Anisotropic Accuracy Across the Space

A deep investigation of proprioceptive processes is necessary to understand the relationship between sensory afferent inputs and motor outcomes. In this work, we investigate whether and how perception of wrist position is influenced by the direction along which the movement occurs. Most previous studies have tested Joint Position Sense (JPS) through 1 degree of freedom (DoF) wrist movements, such as flexion/extension (FE) or radial/ulnar deviation (RUD). However, the wrist joint has 3-DoF and many activities of daily living produce combined movements, requiring at least 2-DoF wrist coordination. For this reason, in this study, target positions involved movement directions that combined wrist flexion or extension with radial or ulnar deviation. The chosen task was a robot-aided Joint Position Matching (JPM), in which blindfolded participants actively reproduced a previously passively assumed target joint configuration. The JPM performance of 20 healthy participants was quantified through measures of accuracy and precision, in terms of both perceived target direction and distance along each direction of movement. Twelve different directions of movement were selected and both hands tested. The left and right hand led to comparable results, both target extents and directions were differently perceived according to the target direction on the FE/RUD space. Moreover, during 2-DoF combined movements, subjects’ perception of directions was impaired when compared to 1-DoF target movements. In summary, our results showed that human perception of wrist position on the FE/RUD space is symmetric between hands but not isotropic among movement directions.

MAIN ASPECTS OF THE LEGAL REGULATION OF A SIMPLE PARTNERSHIP AGREEMENT IN RUSSIA

The current economic conditions, formed under the influence of geopolitical instability and financial crises, complicated by the COVID-19 pandemic, require business structures to find effective areas of activity that allow them to extract maximum financial benefits. This is facilitated by the choice of acceptable organizational and legal forms, among which a special place is given to the contract of a simple partnership. These aspects determine the target direction of the research: they require the study of the essential conditions, distinctive features and characteristics of this institution through the prism of the author’s positions, consideration of the main features and the latest combinations of legal regulation, as well as identification of problematic aspects of the current legislation in this area of legal relations.