442 research outputs found

    Unravelling the contributions of motor experience and conceptual knowledge in action perception: A training study

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    Prior knowledge affects how we perceive the world and the sensorimotor system actively guides our perception. An ongoing dispute regards the extent to which prior motor knowledge versus conceptual knowledge modulates the observation of others’ actions. Research indicates that motor experience increases motor activation during action perception. Other research, however, has shown that conceptual familiarity with actions also modulates motor activation, i.e., increased motor activation during observation of unfamiliar, compared to conceptually familiar, actions. To begin to disentangle motor from conceptual contributions to action perception, we uniquely combined motoric and conceptual interventions into one design. We experimentally manipulated participants’ experience with both motoric skills and conceptual knowledge, via motor training of kinematically challenging actions and contextual information about the action, respectively, in a week-long training session. Measurements of the effects on motor activity measured via electroencephalography (EEG) during pre- and post-training action observation were compared. We found distinct, non-interacting effects of both manipulations: Motor training increased motor activation, whereas additional conceptual knowledge decreased motor activation. The findings indicate that both factors influence action perception in a distinct and parallel manner. This research speaks to previously irreconcilable findings and provides novel insights about the distinct roles of motor and conceptual contributions to action perception

    Changes in anti-viral effectiveness of interferon after dose reduction in chronic hepatitis c patients: a case control study

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    BACKGROUND: High dose interferon induction treatment of hepatitis C viral infection blocks viral production over 95%. Since dose reduction is often performed due to clinical considerations, the effect of dose reduction on hepatitis C virus kinetics was studied. METHODS: A new model that allowed longitudinal changes in the parameters of viral dynamics was used in a group of genotype-1 patients (N = 15) with dose reduction from 10 to 3 million units of interferon daily in combination with ribavirin, in comparison to a control group (N = 9) with no dose reduction. RESULTS: Dose reduction gave rise to a complex viral kinetic pattern, which could be only explained by a decrease in interferon effectiveness in blocking virion production. The benefit of the rapid initial viral decline following the high induction dose is lost after dose reduction. In addition, in some patients also the second phase viral decline slope, which is highly predictive of success of treatment, was impaired by the dose reduction resulting in smaller percentage of viral clearance in the dose reduction group. CONCLUSIONS: These findings, while explaining the failure of many induction schedules, suggest that for genotype-1 patients induction therapy should be continued till HCVRNA negativity in serum in order to increase the sustained response rate for chronic hepatitis C

    Finding robust investments for the Dutch gas distribution infrastructure in 2050 by a scenario study

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    In the changing Dutch energy market, the ageing gas distribution grid needs investments. There is, however, a large uncertainty regarding certain aspects that affect the future role of this gas distribution grid, such as the eventual share of biomethane in the gas mix, whether power-to-gas will take-off and the expected lifetime of the grid. Hence, it is currently unclear what investments need to be made for the gas distribution infrastructure in order to cope with future changes. To find out how the future may unfold for the Dutch gas distribution infrastructure in 2050, four scenarios have been developed. Two key forces – a key force is a factor that has a large impact on the gas distribution grid but great uncertainty exists regarding its outcome – were chosen, namely “perceived energy resource scarcity” and “willingness and ability to reduce greenhouse gas emissions”. Each scenario sketches the future Dutch gas infrastructure by defining, among others, the extent to which biomass will be used to produce biomethane, whether fossil fuel is allowed to be burned locally, and what types of gas will flow through the gas grid. With these scenarios at our disposal, in the next research step, we will establish the impact of the scenarios on the gas distribution grid – i.e. what the layout will be and the corresponding costs – and the accompanying biomethane infrastructure. For this, 3 typical locations were chosen: a rural region, an urban region, and an intermediate region. Through a multi-objective optimization – with maximizing net present value, maximizing biomethane production, and maximizing CO2 emission reduction as objectives – the possible layout of the gas distribution grid and the biomethane infrastructure will be determined for each region. The study’s aim is to find similarities in investments among the different layouts, to come to robust investments for the gas distribution infrastructure

    Action prediction in 10-month-old infants at high and low familial risk for Autism Spectrum Disorder

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    Contains fulltext : 190105pos.pdf (postprint version ) (Closed access)Background: Several studies have reported action prediction difficulties in Autism Spectrum Disorder (ASD). Although action prediction develops in infancy, little is known about prediction abilities in infants at risk for ASD. Methods: Using eye tracking, we measured action anticipations in 52 10-month-old infants at high and low familial risk for ASD. Infants were repeatedly presented with actions during which a familiar object (cup/phone) was either brought to a location usually associated with the object (cup-to-mouth/phone-to-ear; usual condition) or to an unusual location (cup-to-ear/phone-to-mouth; unusual condition). We assessed infants' anticipations to the actual target location (i.e., the location where the object was actually brought; the mouth in cup-to-mouth/phone-to-mouth actions; the ear in cup-to-ear/phone-to-ear actions) and the alternative target location (the ear in cup-to-mouth/phone-to-mouth actions; the mouth in cup-to-ear/phone-to-ear actions). Results: Anticipation frequencies were modulated by object knowledge across all infants: We found more frequent anticipations towards the alternative target location for unusual compared to usual actions. This effect was in particular present for mouth anticipations which were also overall more frequent than ear anticipations. Across usual and unusual actions, infants showed more frequent anticipations towards the actual target location, potentially representing a learning effect elicited by the repeated action presentation. Importantly, there were no differences between the low- and high-risk infants in predictive eye movements. Conclusion: Whereas our results suggest that familial risk for ASD does not affect action prediction in infancy, future research needs to investigate whether differences are apparent in those high-risk infants who later receive a diagnosis.13 p

    Eye–hand coordination during manual object transport with the affected and less affected hand in adolescents with hemiparetic cerebral palsy

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    In the present study we investigated eye–hand coordination in adolescents with hemiparetic cerebral palsy (CP) and neurologically healthy controls. Using an object prehension and transport task, we addressed two hypotheses, motivated by the question whether early brain damage and the ensuing limitations of motor activity lead to general and/or effector-specific effects in visuomotor control of manual actions. We hypothesized that individuals with hemiparetic CP would more closely visually monitor actions with their affected hand, compared to both their less affected hand and to control participants without a sensorimotor impairment. A second, more speculative hypothesis was that, in relation to previously established deficits in prospective action control in individuals with hemiparetic CP, gaze patterns might be less anticipatory in general, also during actions performed with the less affected hand. Analysis of the gaze and hand movement data revealed the increased visual monitoring of participants with CP when using their affected hand at the beginning as well as during object transport. In contrast, no general deficit in anticipatory gaze control in the participants with hemiparetic CP could be observed. Collectively, these findings are the first to directly show that individuals with hemiparetic CP adapt eye–hand coordination to the specific constraints of the moving limb, presumably to compensate for sensorimotor deficits

    Joint action modulates motor system involvement during action observation in 3-year-olds

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    When we are engaged in a joint action, we need to integrate our partner’s actions with our own actions. Previous research has shown that in adults the involvement of one’s own motor system is enhanced during observation of an action partner as compared to during observation of an individual actor. The aim of this study was to investigate whether similar motor system involvement is present at early stages of joint action development and whether it is related to joint action performance. In an EEG experiment with 3-year-old children, we assessed the children’s brain activity and performance during a joint game with an adult experimenter. We used a simple button-pressing game in which the two players acted in turns. Power in the mu- and beta-frequency bands was compared when children were not actively moving but observing the experimenter’s actions when (1) they were engaged in the joint action game and (2) when they were not engaged. Enhanced motor involvement during action observation as indicated by attenuated sensorimotor mu- and beta-power was found when the 3-year-olds were engaged in the joint action. This enhanced motor activation during action observation was associated with better joint action performance. The findings suggest that already in early childhood the motor system is differentially activated during action observation depending on the involvement in a joint action. This motor system involvement might play an important role for children’s joint action performance

    Online prediction of others’ actions: the contribution of the target object, action context and movement kinematics

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    Previous research investigated the contributions of target objects, situational context and movement kinematics to action prediction separately. The current study addresses how these three factors combine in the prediction of observed actions. Participants observed an actor whose movements were constrained by the situational context or not, and object-directed or not. After several steps, participants had to indicate how the action would continue. Experiment 1 shows that predictions were most accurate when the action was constrained and object-directed. Experiments 2A and 2B investigated whether these predictions relied more on the presence of a target object or cues in the actor’s movement kinematics. The target object was artificially moved to another location or occluded. Results suggest a crucial role for kinematics. In sum, observers predict actions based on target objects and situational constraints, and they exploit subtle movement cues of the observed actor rather than the direct visual information about target objects and context
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