RESUMEN
Compact tactile matrix (CTM) is a vibrotactile device composed of a seven-by-seven array of electromechanical vibrators "tactip" used to represent tactile patterns applied to a small skin area. The CTM uses a dynamic feature to generate spatiotemporal tactile patterns. The design requirements focus particularly on maximizing the transmission of the vibration from one tactip to the others as well as to the skin over a square area of 16 cm (2) while simultaneously minimizing the transmission of vibrations throughout the overall structure of the CTM. Experiments were conducted on 22 unpracticed subjects to evaluate how the CTM could be used to develop a tactile semantics for communication of instructions in order to test the ability of the subjects to identify: 1) directional prescriptors for gesture guidance and 2) instructional commands for operational task requirements in a military context. The results indicate that, after familiarization, recognition accuracies in the tactile patterns were remarkably precise for more 80% of the subjects.
Asunto(s)
Tecnología Biomédica/instrumentación , Patrones de Reconocimiento Fisiológico/fisiología , Fenómenos Fisiológicos de la Piel , Tacto/fisiología , Vibración , Abdomen , Adulto , Femenino , Humanos , Masculino , Semántica , Análisis y Desempeño de TareasRESUMEN
Recent studies have highlighted interactions between state anxiety, sensory processing involved in motor performance, and personality traits such as trait anxiety. In the present study, we investigated the effects of moderate state anxiety on static balance performance with eyes open and eyes closed in two groups of healthy subjects with contrasting trait anxiety. We found that an anxiogenic condition induces larger and faster body swaying in both groups in the eyes-open test. This suggests that state anxiety could modify the processing of the different sensory inputs involved in balance control whatever the subjects' trait anxiety level. When vision is absent, precision of static balance control in individuals with intermediate level of trait anxiety - characterized by a higher visual dependence - is more disrupted than in low trait anxiety subjects. Moreover, moderate state anxiety seems to disturb the ability to use vestibular and/or somatosensory inputs in individuals with low anxiety, but not in individuals with intermediate trait anxiety. These results on inter-individual differences provide a first insight into the inter-dependence between trait anxiety, state anxiety and static balance control.
Asunto(s)
Ansiedad/fisiopatología , Equilibrio Postural/fisiología , Ansiedad/diagnóstico , Femenino , Humanos , Masculino , Procesos Mentales , Psicometría , Visión Ocular/fisiología , Adulto JovenRESUMEN
OBJECTIVE: To address the question of the space sensorimotor representation during hand-writing and its modifications with aging. We have chosen to study the drawing ellipses without visual guidance. We hypothesized that the decreased manual dexterity associated with aging could be attributed, in part, to the modification of space representation for action. METHODS: Young and elderly subjects drew ellipses with the tip of the index in the three anatomical planes: sagittal, frontal and horizontal. The 3D movements were recorded by a portable Video Recorder (3DVR) adapted to a clinical examination room with a natural light source. RESULTS: All subjects showed large disparities in errors in the various planes. Errors were maximal in the horizontal plane. These findings confirm the assumption of an anisotropic action-related representation of space when the movement is performed in a peripersonal frame of reference. Compared with young subjects, the results demonstrate that aging is associated with an important decreased ability to draw precisely ellipses in the three body-defined reference frames. CONCLUSION: Space representation is altered with aging. This finding supports the idea that the central nervous system is apparently able to maintain hand-drawing performance at a good level independently of the anisotropic character of the egocentric space. SIGNIFICANCE: These findings may contribute to introducing new functional clinical tests and open new perspectives for future investigations on the age-related changes in hand function.
Asunto(s)
Envejecimiento/fisiología , Mano/fisiología , Escritura Manual , Movimiento/fisiología , Desempeño Psicomotor/fisiología , Percepción Espacial/fisiología , Factores de Edad , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Orientación/fisiología , Enfermedad de Parkinson/diagnóstico , Enfermedad de Parkinson/fisiopatología , Adulto JovenRESUMEN
On the basis of an approach inspired by Shannon's information theory, a Visual Motor Efficiency (VME) index is proposed. This index is an absolute measure of performance because it expresses a percentage of a perfect performance. By means of a Psycho Motor Performance Device (PMPD), this index is used to evaluate psychomotor performance during visual pointing task. Localising was carried out with the help of a unidirectional handle that only allows supination or pronation movements of the wrist to reach targets that appear on a computer screen in the form of a small square along the horizontal (left/right) and vertical (up/down) arms of a cross. The PMPD was designed so that the progress of the visual motor task would be immediately examined. In a pilot study dedicated to track the evolution of performance in six subjects for six consecutive days, we show that the degree of directional coherence between movement and effect produced is an important factor. Indeed the performance level is significantly lower when it is a question of pointing at targets located along the vertical arm compared to pointing at those along the horizontal. These results indicate that PMPD is a valid and sensitive measurement of human psychomotor performance in charting the progress of a subject during training.
Asunto(s)
Estudios de Evaluación como Asunto , Teoría de la Información , Movimiento/fisiología , Desempeño Psicomotor/fisiología , Percepción Visual/fisiología , Adulto , Femenino , Humanos , Masculino , Estimulación Luminosa/métodos , Tiempo de Reacción/fisiología , Análisis y Desempeño de TareasRESUMEN
The principal goal of our study is to gain an insight into the coordinative structure of a complex body movement. As a first step, this paper describes the activity of multiple skeletal muscles associated with the drawing-like movements that resemble the Jeté, performed by skilled ballet dancers. The EMG activity of 18 muscles of the trunk, pelvis, and both legs was recorded when dancers standing on the left leg moved the toe of the right leg forward and backward along a straight line. A major finding is that the EMG activity of all right muscles, despite their functional and anatomical diversity, was minimised not only at the initial, vertical position but also in the reversal phase of movement when the moving leg was maximally deviated from the vertical position. In other words, the activity was minimal when torques of the weights of limb segments were minimal as well as when these torques were maximal. In contrast, in the static task when the maximally deviated leg position was maintained, there was substantial tonic activation of leg muscles, an activity that was necessary to balance these torques. The result is consistent with the hypothesis that movements of the body result from centrally induced changes in the muscle recruitment thresholds influencing the referent configuration of the body. The existence of minima in the overall EMG activity of skeletal muscles is not the only prediction of the referent configuration hypothesis. An immediate consequence of the hypothesis is that, in movements of the limb, the EMG patterns should be a direction-dependent phenomenon known as "directional tuning" of muscles. In combination with the principle of minimal interaction of neuromuscular system, the referent configuration hypothesis offers a dynamic approach to the problems of how control levels may guide multi-muscle and multi-joint systems without redundancy problems.
Asunto(s)
Baile/fisiología , Destreza Motora/fisiología , Movimiento/fisiología , Músculo Esquelético/fisiología , Equilibrio Postural , Postura , Electromiografía/métodos , Femenino , HumanosRESUMEN
The principal goal of our study is to gain an insight into the representation of peripersonal space. Two different experiments were conducted in this study. In the first experiment, subjects were asked to represent principal anatomical reference planes by drawing ellipses in the sagittal, frontal and horizontal planes. The three-dimensional hand-drawing movements, which were achieved with and without visual guidance, were considered as the expression of a cognitive process per se: the peripersonal space representation for action. We measured errors in the spatial orientation of ellipses with regard to the requested reference planes. For ellipses drawn without visual guidance, with eyes open and eyes closed, orientation errors were related to the reference planes. Errors were minimal for sagittal and maximal for horizontal plane. These disparities in errors were considerably reduced when subjects drew using a visual guide. These findings imply that different planes are centrally represented, and are characterized, by different errors when subjects use a body-centered frame for performing the movement and suggest that the representation of peripersonal space may be anisotropic. However, this representation can be modified when subjects use an environment-centered reference frame to produce the movement. In the second experiment, subjects were instructed to represent, with eyes open and eyes closed, sagittal, frontal and horizontal planes by pointing to virtual targets located in these planes. Disparities in orientation errors measured for pointing were similar to those found for drawing, implying that the sensorimotor representation of reference planes was not constrained by the type of motor tasks. Moreover, arm postures measured at pointing endpoints and at comparable spatial locations in drawing are strongly correlated. These results suggest that similar patterns of errors and arm posture correlation, for drawing and pointing, can be the consequence of using a common space representation and reference frame. These findings are consistent with the assumption of an anisotropic action-related representation of peripersonal space when the movement is performed in a body-centered frame.