Proprioceptive Movement Illusions Due to Prolonged Stimulation: Reversals and Aftereffects

Background. Adaptation to constant stimulation has often been used to investigate the mechanisms of perceptual coding, but the adaptive processes within the proprioceptive channels that encode body movement have not been well described. We investigated them using vibration as a stimulus because vibration of muscle tendons results in a powerful illusion of movement. Methodology/Principal Findings. We applied sustained 90 Hz vibratory stimulation to biceps brachii, an elbow flexor and induced the expected illusion of elbow extension (in 12 participants). There was clear evidence of adaptation to the movement signal both during the 6-min long vibration and on its cessation. During vibration, the strong initial illusion of extension waxed and waned, with diminishing duration of periods of illusory movement and occasional reversals in the direction of the illusion. After vibration there was an aftereffect in which the stationary elbow seemed to move into flexion. Muscle activity shows no consistent relationship with the variations in perceived movement. Conclusion. We interpret the observed effects as adaptive changes in the central mechanisms that code movement in direction-selective opponent channels

A neural network model for the intersensory coordination involved in goal-directed movements

International audienceA neural network model for a sensorimotor system, which was developed to simulate oriented movements in man, is presented. It is composed of a formal neural network comprising two layers: a sensory layer receiving and processing sensory inputs, and a motor layer driving a simulated arm. The sensory layer is an extension of the topological network previously proposed by Kohonen (1984). Two kinds of sensory modality, proprioceptive and exteroceptive, are used to define the arm position. Each sensory cell receives proprioceptive inputs provided by each arm-joint together with the exteroceptive inputs. This sensory layer is therefore a kind of associative layer which integrates two separate sensory signals relating to movement coding. It is connected to the motor layer by means of adaptive synapses which provide a physical link between a motor activity and its sensory consequences. After a learning period, the spatial map which emerges in the sensory layer clearly depends on the sensory inputs and an associative map of both the arm and the extra-personal space is built up if proprioceptive and exteroceptive signals are processed together. The senso-rimotor transformations occuring in the junctions linking the sensory and motor layers are organized in such a manner that the simulated arm becomes able to reach towards and track a target in extra-personal space. Proprioception serves to determine the final arm posture adopted and to correct the ongoing movement in cases where changes in the target location occur. With a view to developing a sensorimotor control system with more realistic salient features, a robotic model was coupled with the formal neural network. This robotic implementation of our model shows the capacity of formal neural networks to control the displacement of mechanical devices

Cell‐assisted lipotransfer: Friend or foe in fat grafting? Systematic review and meta‐analysis

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[Accepted Manuscript] Incidence of major smoking-related cancers: trends among adults aged 20-44 in France from 1982 to 2012

Tobacco is currently the largest risk factor for cancers of the lung, lip/oral cavity/pharynx (LOCP) and esophagus. Variations in tobacco consumption over time have led to changes in cancer incidence in the general population. Data on the incidence of cancers at these sites in adults aged 20-44 years old are scarce. Our objective was to provide estimates of incidence trends for these cancers in France among this age group over the last 30 years. Observed incidence data over the period 1982-2010 for the 20-44 age group were provided from six cancer registries (eight for esophagus) covering approximately 6% of the French population. Age-period-cohort models were used on the observed period, and estimates of cancer incidence for France in 2012 were provided on the basis of short-term predictions. In men, a sharp decline was observed over time for LOCP and esophageal cancers, while lung cancer saw only a slight decline. In women, a large increase was seen in lung cancer incidence, while LOCP cancer incidence did not vary significantly. Smoking behaviors among adults aged 20-44 impact incidence trends in cancers of the lung, LOCP and esophagus, although other factors are involved, particularly in LOCP and esophageal cancers. Our results highlight the importance of preventative efforts which particularly target women aged 20-44. Efforts to curb tobacco smoking in men should also be pursued

Early Differentiation of Pseudoprogression for Recurrent Glioblastoma in STERIMGLI Trial Using Multimodal MRI Radiomics Signature

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Comparison of variable selection methods for high-dimensional survival data with competing events

In the era of personalized medicine, it's primordial to identify gene signatures for each event type in the context of competing risks in order to improve risk stratification and treatment strategy. Until recently, little attention was paid to the performance of high-dimensional selection in deriving molecular signatures in this context. In this paper, we investigate the performance of two selection methods developed in the framework of high-dimensional data and competing risks: Random survival forest and a boosting approach for fitting proportional subdistribution hazards models

Statistical controversies in clinical research: should schedules of tumor size assessments be changed?

International audienceBACKGROUND:Time to progression (TTP) is often used as a primary end point in phase II clinical trials. Since the actual date of nadir and progression is never known, most calculated TTP are overestimated. This study evaluates the imprecision on the estimate of TTP under two hypothetical tumor kinetic settings and various assessment schedules.DESIGN:A two-component tumor growth model was used to account for treatment effect assuming exponential decay for tumor shrinkage and linear growth for progression. Evolution of tumor burden (TB) was modelized according to two scenarios using either a cytotoxic or a cytostatic agent and several assessment schedules. TB, nadir, progression and TTP were simulated for each visit schedule.RESULTS:For cytotoxic agents, our model predicted response at 1.5 weeks, a TB at nadir of 40.2 mm (starting from 100 mm) occurring at 6.7 weeks and true progression at 11.2 weeks with a TB of 48.2 mm. For cytostatic agents, our model predicted no response, a TB at nadir of 77 mm occurring at 9.2 weeks and true progression at 19.4 weeks with a TB of 92 mm. Depending on the assessment schedule, estimated TTP was increased from 0.8 to 36.8 weeks and from 0.6 to 28.6 weeks when compared with the true TTP and varied from 5.2% to 298% and from 1.66 to 109.58% when compared with the true TB at progression for cytotoxic and cytostatic agents, respectively. Our model further shows that for cytotoxic agents, evaluation of TB every 6 weeks is optimal to capture the true nadir, the time to nadir, the true progression and the true TTP, whereas for cytostatic agents, this evaluation is optimal every 10 weeks.CONCLUSIONS:Our results emphasize the importance to estimate the effects of tested drugs on tumor shrinkage before design any phase II clinical trials to choose optimal TB evaluation's timing