1,721,038 research outputs found
Leonardo da Vinci 1452-1519. Il Disegno del mondo
No full textIl volume costituisce il Catalogo scientifico dell'omonima Mostra tenutasi a Palazzo Reale di Milano dal 15 aprile al 19 luglio 2015
Do placebo effects improve my skill?
No full textMotor performance is multifaceted and refers to several different dimensions, including force production, precision control, movement speed, resistance to fatigue, motor adaptation, and motor skill learning. The investigation of the placebo effect on different motor functions represents a useful approach to extend our knowledge about the pervasive nature of this effect and build new models for the study of its neural underpinnings. To date, while many behavioral studies have demonstrated the efficacy of placebo and nocebo procedures in influencing some aspects of motor performance, others remain unexplored. In this chapter, two categories of motor functions will be considered: those performed with the upper limb and those requiring the whole body. Within the first category, evidence using a fundamental function through which repeated practice forms isolated movements into well-performed skills will be presented on force production, goal-directed movements, and motor sequence learning. Within the second category, evidence will be presented on balance control, a fundamental motor function, which allows to maintain a stable stance and to prevent falls, as well as on leg-extension performance
Proprioceptive drift is affected by the intermanual distance rather than the distance from the body’s midline in the rubber hand illusion
No full textIn the rubber hand illusion (RHI), simultaneous brush stroking of a subject’s hidden hand and a visible rubber hand induces a transient illusion of the latter to “feel like it’s my hand” and a proprioceptive drift of the hidden own hand toward the rubber hand. Recent accounts of the RHI have suggested that the illusion would only occur if weighting of conflicting sensory information and their subsequent integration results in a statistically plausible compromise. In three different experiments, we investigated the role of distance between the two hands as well as their proximity to the body’s midline in influencing the occurrence of the illusion. Overall, the results suggest that the illusion is abolished when placing the two hands apart, therefore increasing the mismatch between the visual and proprioceptive modality, whereas the proximity of the two hands to the body’s midline plays only a minor role on the subjective report of the illusion. This might be driven by the response properties of visuotactile bimodal cells encoding the peripersonal space around the hand
Selective impairment of hand mental rotation in patients with focal hand dystonia.
No full textMental rotation of body parts determines activation of cortical and subcortical systems involved in motor planning and execution, such as motor and premotor areas and basal ganglia. These structures are severely impaired in several movement disorders, including dystonia. Writer's cramp is the most common form of focal hand dystonia. This study investigates whether patients affected by writer's cramp present with difficulties in tasks involving mental rotation of body parts and whether any impairments are specific to the affected hand or generalized to other body parts. For this purpose we tested 15 patients with right writer's cramp (aged 21-68 years, 8 women) and 15 healthy control subjects (10 women, age and education matched). Stimuli consisted of realistic photographs of hands and feet presented on a computer monitor in different orientations with respect to the upright canonical orientation. In each trial, subjects gave a laterality judgement by reporting verbally whether the presented body part was left or right. Two main results of the study are, firstly, writer's cramp patients are slower than controls in mentally rotating hands [F (1,28) = 5.4; P = 0.028] but not feet, and secondly, the pattern of response times to stimuli at various orientations suggests that the mental motor imagery of controls and patients reflects the type of processes and mechanisms called into play during actual execution of the same movements. In particular, increased difficulty in rotating right-sided stimuli at 120 degrees and left-sided stimuli at 240 degrees would suggest that mental rotation of body parts reflects the anatomical constraints of real hand movements. In conclusion, patients with writer's cramp presented mental rotation deficits specific to the hand. Importantly, deficits were present during mental rotation of both the right (affected) and the left (unaffected) hand, thus suggesting that the observed alterations may be independent and even exist prior to overt manifestations of dystonia
The interplay of exercise, placebo and nocebo effects on experimental pain
Full text linkOver the last few decades, placebo, and nocebo effects in general, have been investigated at rest. This proposed study explores whether they could work even when the experience of pain occurs during a movement. Exercise itself can have a hypoalgesic effect, suggesting that placebo- and exercise-induced hypoalgesia could foster pain reduction. In the present study, we investigated the interplay of exercise, placebo and nocebo effects on pain. To this aim, we developed a machine-controlled isotonic motor task to standardize the exercise across participants and used a well-validated model of placebo and nocebo manipulations with reinforced expectations via a conditioning procedure including visual cues paired with heat painful stimulations. Participants reported expectations and pain on a trial-by-trial basis. We found that the standardized isotonic exercise elicited a reduction of pain intensity. Moreover, both exercise and placebo induced comparable hypoalgesic effects. When the exercise was added, placebo and nocebo effects were influenced by expectations but were not affected by fatigue or sex differences. Exercise-, placebo- and nocebo-induced pain modulation are likely to work through distinct mechanisms and neurophysiological research is needed to fully exploit the implications for sport, rehabilitation and pain management
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Temporal discrimination of cross-modal and unimodal stimuli in generalised dystonia
No full textBackground: Motor and nonmotor timing functions and cross-modal processing of visual-tactile signals may be linked to basal ganglia. These neural structures are thought to be dysfunctional in dystonia. Objective: To test whether cross-modal stimulation influences deficits of temporal discrimination in dystonia. Methods: Eight patients with generalized dystonia and 10 control subjects were asked to discriminate whether pairs of unimodal (tactile or visual) and cross-modal (visual and tactile) stimuli were simultaneous or sequential and, in the latter case, which stimulus preceded the other. Visual stimuli consisted of red lights and tactile stimuli of non-noxious electrical shocks. Intervals between stimuli in each pair were increased from 0 to 400 msee (in steps of 10 msec). Results: Patients with dystonia recognized the asynchrony between the experimental stimuli and judged correctly which stimulus in a pair came first, at significantly longer intervals than did controls. Moreover, differences in performance between patients and controls were maximal for cross-modal stimuli. The defective performance of patients with dystonia in the cross-modal combinations showed a high positive correlation with the severity of symptoms. Conclusions: Patients with generalized dystonia present with difficulties both in timing functions and in cross-modal processing of visual-tactile stimuli
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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