Comparing the efficacy of metronome beeps and stepping stones to adjust gait: steps to follow!

Acoustic metronomes and visual targets have been used in rehabilitation practice to improve pathological gait. In addition, they may be instrumental in evaluating and training instantaneous gait adjustments. The aim of this study was to compare the efficacy of two cue types in inducing gait adjustments, viz. acoustic temporal cues in the form of metronome beeps and visual spatial cues in the form of projected stepping stones. Twenty healthy elderly (aged 63.2 ± 3.6 years) were recruited to walk on an instrumented treadmill at preferred speed and cadence, paced by either metronome beeps or projected stepping stones. Gait adaptations were induced using two manipulations: by perturbing the sequence of cues and by imposing switches from one cueing type to the other. Responses to these manipulations were quantified in terms of step-length and step-time adjustments, the percentage correction achieved over subsequent steps, and the number of steps required to restore the relation between gait and the beeps or stepping stones. The results showed that perturbations in a sequence of stepping stones were overcome faster than those in a sequence of metronome beeps. In switching trials, switching from metronome beeps to stepping stones was achieved faster than vice versa, indicating that gait was influenced more strongly by the stepping stones than the metronome beeps. Together these results revealed that, in healthy elderly, the stepping stones induced gait adjustments more effectively than did the metronome beeps. Potential implications for the use of metronome beeps and stepping stones in gait rehabilitation practice are discussed

Subliminal stimuli in the near absence of attention influence top-down cognitive control

Recent research has shown that visual stimuli can influence cognitive control functions, even if subjects are unaware of the identity of the stimuli. However, in those previous studies, subjects actively attended to the location of the subliminal stimuli. Here we assessed the role of endogenous spatial attention in such paradigms. We required subjects to quickly prepare for one of two numerical judgment tasks on the basis of the direction of motion in patches of moving dots presented in cued spatial locations. We found that irrelevant motion patches presented in the uncued spatial locations also influenced task performance. Motion in the uncued patches was weak and did not affect the perception of the cued patches. Further analyses suggested that the effect of priming by the uncued stimuli was present even for subjects who could only discriminate such stimuli at chance level. Three additional experiments confirmed that subjects paid minimal attention to the uncued locations, in that the subjects could not perform simple discriminations of conjunctions of features in those locations

Altered visual feedback from an embodied avatar unconsciously influences movement amplitude and muscle activity

Evidence suggests that the sense of the position of our body parts can be surreptitiously deceived, for instance through illusory visual inputs. However, whether altered visual feedback during limb movement can induce substantial unconscious motor and muscular adjustments is not known. To address this question, we covertly manipulated virtual body movements in immersive virtual reality. Participants were instructed to flex their elbow to 90° while tensing an elastic band, as their virtual arm reproduced the same, a reduced (75°), or an amplified (105°) movement. We recorded muscle activity using electromyography, and assessed body ownership, agency and proprioception of the arm. Our results not only show that participants compensated for the avatar’s manipulated arm movement while being completely unaware of it, but also that it is possible to induce unconscious motor adaptations requiring significant changes in muscular activity. Altered visual feedback through body ownership illusions can influence motor performance in a process that bypasses awareness

Los espacios eróticos en Prosas profanas de Rubén Darío

Esta ponencia se propone estudiar algunos de los espacios presentes en Prosas profanas de Rubén Darío. A partir de las apreciaciones propuestas por Claude Calame en Eros en la Antigua Grecia quien distingue los espacios de la pólis desde lo femenino y desde lo masculino. Estos últimos, están integrados en la ciudad y son propios de Eros y los primeros están en los prados, confundidos con jardines, llenos de flores, ámbitos donde comienzan los juegos eróticos para pasar a los jardines de Afrodita en los que se da la transición de la adolescencia a la madurez sexual (Calame, 2002, p. 160). Así también, en la poesía del nicaragüense los espacios, como los jardines versallescos, palacios o salones, son los que albergan al erotismo y a las figuras femeninas que analizamos detenidamente en consonancia con la tradición clásica. La Belleza sobrenatural de las diosas grecorromanas y la belleza femenina en general van a conducir y traducir a la poesía misma y a eso apunta nuestro trabajo. Veremos así, cómo la elección de Eros en vez de Venus o al revés nos marcan el camino para una lectura de la concepción erótica del poeta, un itinerario hacia la consumación del amor o hacia la conquista y los juegos del deseo

Virtual Reality Reveals Mechanisms of Balance and Locomotor Impairments

This chapter reviews how VR can be used to investigate normal and disturbed mechanisms of balance and locomotor control. Loss of upright balance control resulting in falls is a major health problem for older adults and stroke survivors. Balance and mobility deficits arise not only from motor or sensory impairments but also from the inability to select and reweight pertinent sensory information. In particular, the role of the vestibular system and effects of age and stroke on the ability of the central nervous system to resolve sensory conflicts is emphasized, as well as the potential for rehabilitation protocols that include training in virtual environments to improve balance