D'Alembert formula on finite one-dimensional networks

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Novel asleep techniques for intraoperative assessment of brain connectivity

[no abstract available

Fancies and Fallacies of Spatial Sampling With Transcranial Magnetic Stimulation (TMS)

[no abstract available

Gaze direction influences grasping actions towards unseen, haptically explored, objects

Haptic exploration produces mental object representations that can be memorized for subsequent object-directed behaviour. Storage of haptically-acquired object images (HOIs), engages, besides canonical somatosensory areas, the early visual cortex (EVC). Clear evidence for a causal contribution of EVC to HOI representation is still lacking. The use of visual information by the grasping system undergoes necessarily a frame of reference shift by integrating eye-position. We hypothesize that if the motor system uses HOIs stored in a retinotopic coding in the visual cortex, then its use is likely to depend at least in part on eye position. We measured the kinematics of 4 fingers in the right hand of 15 healthy participants during the task of grasping different unseen objects behind an opaque panel, that had been previously explored haptically. The participants never saw the object and operated exclusively based on haptic information. The position of the object was fixed, in front of the participant, but the subject's gaze varied from trial to trial between 3 possible positions, towards the unseen object or away from it, on either side. Results showed that the middle and little fingers' kinematics during reaching for the unseen object changed significantly according to gaze position. In a control experiment we showed that intransitive hand movements were not modulated by gaze direction. Manipulating eye-position produces small but significant configuration errors, (behavioural errors due to shifts in frame of reference) possibly related to an eye-centered frame of reference, despite the absence of visual information, indicating sharing of resources between the haptic and the visual/oculomotor system to delayed haptic grasping

Broken affordances, broken objects: A TMS study

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Eye and hand movements disrupt attentional control

Voluntary attentional control is the ability to selectively focus on a subset of visual information in the presence of other competing stimuli–a marker of cognitive control enabling flexible, goal-driven behavior. To test its robustness, we contrasted attentional control with the most common source of attentional orienting in daily life: attention shifts prior to goal-directed eye and hand movements. In a multi-tasking paradigm, human participants attended at a location while planning eye or hand movements elsewhere. Voluntary attentional control suffered with every simultaneous action plan, even under reduced task difficulty and memory load–factors known to interfere with attentional control. Furthermore, the performance cost was limited to voluntary attention: We observed simultaneous attention benefits at two movement targets without attentional competition between them. This demonstrates that the visual system allows for the concurrent representation of multiple attentional foci. Since attentional control is extremely fragile and dominated by premotor attention shifts, we propose that action-driven selection plays the superordinate role for visual selection

Feasibility of cerebello-cortical stimulation for intraoperative neurophysiological monitoring of cerebellar mutism

BACKGROUND: Cerebellar mutism can occur in a third of children undergoing cerebellar resections. Recent evidence proposes it may arise from uni- or bilateral damage of cerebellar efferents to the cortex along the cerebello-dento-thalamo-cortical pathway. At present, no neurophysiological procedure is available to monitor this pathway intraoperatively. Here, we specifically aimed at filling this gap.METHODS: We assessed 10 patients undergoing posterior fossa surgery using a conditioning-test stimulus paradigm. Electrical conditioning stimuli (cStim) were delivered to the exposed cerebellar cortex at interstimulus intervals (ISIs) of 8-24 ms prior to transcranial electric stimulation of the motor cortex, which served as test stimulus (tStim). The variation of motor-evoked potentials (MEP) to cStim + tStim compared with tStim alone was taken as a measure of cerebello-cortical connectivity.RESULTS: cStim alone did not produce any MEP. cStim preceding tStim produced a significant inhibition at 8 ms (p < 0.0001) compared with other ISIs when applied to the lobules IV-V-VI in the anterior cerebellum and the lobule VIIB in the posterior cerebellum. Mixed effects of decrease and increase in MEP amplitude were observed in these areas for longer ISIs.CONCLUSIONS: The inhibition exerted by cStim at 8 ms on the motor cortex excitability is likely to be the product of activity along the cerebello-dento-thalamo-cortical pathway. We show that monitoring efferent cerebellar pathways to the motor cortex is feasible in intraoperative settings. This study has promising implications for pediatric posterior fossa surgery with the aim to preserve the cerebello-cortical pathways and thus prevent cerebellar mutism

Post-Failure Behavior of Point-Fixing Laminated Glass Plates under Out-of-Plane Uniform Pressure

This paper presents the results of an experimental and numerical investigation of the mechanical response of undamaged and damaged 2-ply laminated glass plates. Two types of glass plies, thermally toughened and heat-strengthened, coupled with SentryGlas (SG) were considered. Laminated glass plates supported with articulated point fixing bolt under out-of-plane uniform pressure were investigated under four different damage configurations: (i) undamaged; (ii) partially damaged, with the bottom ply broken; (iii) partially damaged, over-flipping the specimen of mode II; (iv) both two glass plies broken, which was applicable for LG plates made by heat-strengthened glass. In the above four modes, the top ply is always subjected to compression while the bottom one is in tension. The different responses of each configuration (different glass types and damage modes) were discussed and compared in this study. In addition, numerical models were adopted to reproduce the experimental results. The influence of the hitting location and glass types on the mechanical behavior of LG plates was analyzed. The results showed that the contribution of the broken glass ply could not be disregarded in the evaluation of the global stiffness of partially damaged LG plates and their bearing capacity

Acellular Dermal Matrices and Radiotherapy in Breast Reconstruction: A Systematic Review and Meta-Analysis of the Literature

The increasing use of commercially available acellular dermis matrices for postmastectomy breast reconstruction seems to have simplified the surgical procedure and enhanced the outcome. These materials, generally considered to be highly safe or with only minor contraindications due to the necessary manipulation in preparatory phases, allow an easier one-phase surgical procedure, in comparison with autologous flaps, offering a high patient satisfaction. Unfortunately, the claim for a higher rate of complications associated with irradiation at the implant site, especially when the radiation therapy was given before the reconstructive surgery, suggested a careful behaviour when this technique is preferred. However, this hypothesis was never submitted to a crucial test, and data supporting it are often discordant or incomplete. To provide a comprehensive analysis of the field, we searched and systematically reviewed papers published after year 2005 and registered clinical trials. On the basis of a meta-analysis of data, we conclude that the negative effect of the radiotherapy on the breast reconstruction seems to be evident even in the case of acellular dermis matrices aided surgery. However, more trials are needed to make solid conclusions and clarify the poor comprehension of all the factors negatively influencing outcome

Upregulation of Myxovirus-resistance Protein A: A Possible Marker of Type I Interferon Induction in Systemic Sclerosis

ObjectiveTo examine whether myxovirus-resistance protein A (MxA) mRNA expression, commonly considered a reliable marker of Type I interferon (IFN) bioactivity, is modified in patients with systemic sclerosis (SSc); if it is associated to specific clinical features; and if its modulation is accompanied by modulation of mRNA for the Type I IFN receptor (IFNAR).MethodsQuantification of mRNA for MxA and the subunit IFNAR1 and isoforms of IFNAR2 was performed by real-time polymerase chain reaction in 50 patients with SSc. Results were compared with those obtained from healthy controls and patients with another autoimmune disease such as multiple sclerosis.ResultsLevels of MxA mRNA above the 99th percentile of values found in healthy controls were observed in 9 out of 50 patients with SSc (p < 0.001). Induced MxA expression was significantly associated with some features of more severe disease, such as lower forced vital capacity and the presence of ischemic digital ulcers. No differences in the levels of IFNAR were found within MxA-induced and MxA-non-induced patients, but there was a direct correlation between levels of MxA and the soluble isoform of IFNAR2.ConclusionOur results show induction of MxA expression in some patients with SSc, which correlates with the presence of ischemic ulcers and other signs of worse disease, suggesting a potential role of Type I IFN in the pathogenesis of this disease and/or its complications