739 research outputs found

    Asymmetry in kinematic generalization between visual and passive lead-in movements are consistent with a forward model in the sensorimotor system

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    In our daily life we often make complex actions comprised of linked movements, such as reaching for a cup of coffee and bringing it to our mouth to drink. Recent work has highlighted the role of such linked movements in the formation of independent motor memories, affecting the learning rate and ability to learn opposing force fields. In these studies, distinct prior movements (lead-in movements) allow adaptation of opposing dynamics on the following movement. Purely visual or purely passive lead-in movements exhibit different angular generalization functions of this motor memory as the lead-in movements are modified, suggesting different neural representations. However, we currently have no understanding of how different movement kinematics (distance, speed or duration) affect this recall process and the formation of independent motor memories. Here we investigate such kinematic generalization for both passive and visual lead-in movements to probe their individual characteristics. After participants adapted to opposing force fields using training lead-in movements, the lead-in kinematics were modified on random trials to test generalization. For both visual and passive modalities, recalled compensation was sensitive to lead-in duration and peak speed, falling off away from the training condition. However, little reduction in force was found with increasing lead-in distance. Interestingly, asymmetric transfer between lead-in movement modalities was also observed, with partial transfer from passive to visual, but very little vice versa. Overall these tuning effects were stronger for passive compared to visual lead-ins demonstrating the difference in these sensory inputs in regulating motor memories. Our results suggest these effects are a consequence of state estimation, with differences across modalities reflecting their different levels of sensory uncertainty arising as a consequence of dissimilar feedback delays

    Neural Tuning Functions Underlie Both Generalization and Interference

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    In sports, the role of backswing is considered critical for generating a good shot, even though it plays no direct role in hitting the ball. We recently demonstrated the scientific basis of this phenomenon by showing that immediate past movement affects the learning and recall of motor memories. This effect occurred regardless of whether the past contextual movement was performed actively, passively, or shown visually. In force field studies, it has been shown that motor memories generalize locally and that the level of compensation decays as a function of movement angle away from the trained movement. Here we examine if the contextual effect of past movement exhibits similar patterns of generalization and whether it can explain behavior seen in interference studies. Using a single force-field learning task, the directional tuning curves of both the prior contextual movement and the subsequent force field adaptive movements were measured. The adaptation movement direction showed strong directional tuning, decaying to zero by 90Ā° relative to the training direction. The contextual movement direction exhibited a similar directional tuning, although the effect was always above 60%. We then investigated the directional tuning of the passive contextual movement using interference tasks, where the contextual movements that uniquely specified the force field direction were separated by Ā±15Ā° or Ā±45Ā°. Both groups showed a pronounced tuning effect, which could be well explained by the directional tuning functions for single force fields. Our results show that contextual effect of past movement influences predictive force compensation, even when adaptation does not require contextual information. However, when such past movement contextual information is crucial to the task, such as in an interference study, it plays a strong role in motor memory learning and recall. This work demonstrates that similar tuning responses underlie both generalization of movement direction during dynamic learning and contextual movements in both single force field and interference tasks

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    Molecular Probe Optimization to Determine Cell Mortality in a Photosynthetic Organism (Microcystis aeruginosa) Using Flow Cytometry

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    Microbial sub populations in field and laboratory studies have been shown to display high heterogeneity in morphological and physiological parameters. Determining the real time state of a microbial cell goes beyond live or dead categories, as microbes can exist in a dormant state, whereby cell division and metabolic activities are reduced. Given the need for detection and quantification of microbes, flow cytometry (FCM) with molecular probes provides a rapid and accurate method to help determine overall population viability. By using SYTOX Green and SYTOX Orange in the model cyanobacteria Microcystis aeruginosa to detect membrane integrity, we develop a transferable method for rapid indication of single cell mortality. The molecular probes used within this journal will be referred to as green or orange nucleic acid probes respectively (although there are other products with similar excitation and emission wavelengths that have a comparable modes of action, we specifically refer to the fore mentioned probes). Protocols using molecular probes vary between species, differing principally in concentration and incubation times. Following this protocol set out on M.aeruginosa the green nucleic acid probe was optimized at concentrations of 0.5 Ī¼M after 30 min of incubation and the orange nucleic acid probe at 1 Ī¼M after 10 min. In both probes concentrations less than the stated optimal led to an under reporting of cells with membrane damage. Conversely, 5 Ī¼M concentrations and higher in both probes exhibited a type of non-specific staining, whereby 'live' cells produced a target fluorescence, leading to an over representation of 'non-viable' cell numbers. The positive controls (heat killed) provided testable dead biomass, although the appropriateness of control generation remains subject to debate. By demonstrating a logical sequence of steps for optimizing the green and orange nucleic acid probes we demonstrate how to create a protocol that can be used to analyse cyanobacterial physiological state effectively

    Governing the soil: Natural farming and bionationalism in India

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    This article examines Indiaā€™s response to the global soil health crisis. A longstanding centre of agricultural production and innovation, India has recently launched an ambitious soil health programme. The countryā€™s Soil Health Card (SHC) Scheme intervenes in farm-scale decisions about efficient fertiliser use, envisioning farmers as managers and soil as a substrate for production. India is also home to one of the worldā€™s largest alternative agriculture movements: natural farming. This puts farmer expertise at the centre of soil fertility and attends to the wider ecological health of soils. Despite emerging as a mode of resistance to dominant agricultural systems, natural farming is now being delivered in increasingly bureaucratic ways by Indiaā€™s state governments. This article offers Himachal Pradesh as a case study in how the soil is governed, drawing on 38 semi-structured interviews with scientists, agricultural officers, non-governmental organisation leaders, and activists. Rather than assess approaches to soil health according to their ecological bottom line, we examine the differing forms of knowledge, expertise and ā€˜truthā€™ in the SHC and Natural Farming approaches. Our analysis reveals discontinuities in how farmers are imagined, as well as continuities in how quasi-spiritual language combines in a bionationalist project, positing assumptions about the correct arrangement of life in nationalist terms. We point to a shift toward hybrid and pick-and-mix approaches to soil health, as farmers and their organisers are increasingly invested with the capacities to combine multiple options. We see a fracturing of expertise and the opening up of epistemic pluralism in responses to the soil fertility crisis

    The value of the follow-through derives from motor learning depending on future actions.

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    In ball sports, we are taught to follow through, despite the inability of events after contact or release to influence the outcome [1, 2]. Here we show that the specific motor memory active at any given moment critically depends on the movement that will be made in the near future. We demonstrate that associating a different follow-through movement with two motor skills that normally interfere [3-7] allows them to be learned simultaneously, suggesting that distinct future actions activate separate motor memories. This implies that when learning a skill, a variable follow-through would activate multiple motor memories across practice, whereas a consistent follow-through would activate a single motor memory, resulting in faster learning. We confirm this prediction and show that such follow-through effects influence adaptation over time periods associated with real-world skill learning. Overall, our results indicate that movements made in the immediate future influence the current active motor memory. This suggests that there is a critical time period both before [8] and after the current movement that determines motor memory activation and controls learning.This is the final published version. The article was originally published in Current Biology, Volume 25, Issue 3, p397ā€“401, 2 February 2015, DOI: 10.1016/j.cub.2014.12.03

    Major genes and QTL influencing wool production and quality: a review

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    The opportunity exists to utilise our knowledge of major genes that influence the economically important traits in wool sheep. Genes with Mendelian inheritance have been identified for many important traits in wool sheep. Of particular importance are genes influencing pigmentation, wool quality and the keratin proteins, the latter of which are important for the morphology of the wool fibre. Gene mapping studies have identified some chromosomal regions associated with variation in wool quality and production traits. The challenge now is to build on this knowledge base in a cost-effective way to deliver molecular tools that facilitate enhanced genetic improvement programs for wool sheep

    Cardiac rehabilitation in rural and remote areas of North Queensland: how well are we doing?

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    Objective: To address access to cardiac rehabilitation (CR) for people in R&R areas, this research aimed to investigate: (1) post discharge systems and support for people returning home from hospital following treatment for heart disease (HD). (2) propose changes to improve access to CR in R&R areas of NQ. Setting: Four focus communities in R&R areas of NQ. Participants: Focus communitiesā€™ health staff (resident/visiting) (57), community leaders (10) and community residents (44), discharged from hospital in past 5 years following treatment for heart disease (purposeful sampling). Design: A qualitative descriptive case study, with data collection via semi-structured interviews. Inductive/deductive thematic analysis was used to identify primary and secondary themes. Health service audit of selected communities. Results: Health services in the focus communities included multipurpose health services, and primary health care centres staffed by resident and visiting staff that included nurses, Aboriginal and Torres Strait Islander Health Workers, medical officers, and allied health professionals. Post-discharge health care for people with HD was predominantly clinical. Barriers to CR included low referrals to community-based health professions by discharging hospitals; poorly defined referral pathways; lack of guidelines; inadequate understanding of holistic, multidisciplinary CR by health staff, community participants and leaders; limited centre-based CR services; lack of awareness, or acceptance of telephone support services. Conclusion: To address barriers identified for CR in R&R areas, health care systemsā€™ revision, including development of referral pathways to local health professionals, CR guidelines and in-service education, is required to developing a model of care that focuses on self-management and education: Heart: Road to Health

    Relational Contracting In A Digital Age; Panel Discussion

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    If, as it has sometimes been argued, changes in contract rules and theory are strongly affected by changes in economic conditions, we should note that the world has changed a good deal since the early 1960s when relational contract theory began to bloom. The economic world of 2004 is very different from the world of 1964. Modern relational contract theory was born about the same time as its great theoretical competitor, the rational choice approach of the legal economists. It came before the vast changes wrought by the information revolution and the increased globalization of the economy. What has relational theory taught us over the past forty years? How has it changed and adapted in light of those great economic changes? Where is it going in the future? Those were the general topics at a panel discussion which took place June 8, 2004, at the Oxstalls campus of the University of Gloucestershire in Gloucester, England. It was part of a conference entitled, The Common Law of Contracts as a World Force in Two Ages of Revolution, which marked the 150th anniversary of one of the most famous contracts cases of all time, Hadley v. Baxendale, and is the theme of the present Symposium. The Conference\u27s object was to explore how the common law adapts to and influences the kind of revolutionary changes that have swept over our society in the past forty years, and which swept over England in the forty years before Hadley v. Baxendale

    Cyanobacterial Abundance and Microcystin Profiles in Two Southern British Lakes: The Importance of Abiotic and Biotic Interactions.

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    Freshwater cyanobacteria blooms represent a risk to ecological and human health through induction of anoxia and release of potent toxins; both conditions require water management to mitigate risks. Many cyanobacteria taxa may produce microcystins, a group of toxic cyclic heptapeptides. Understanding the relationships between the abiotic drivers of microcystins and their occurrence would assist in the implementation of targeted, cost-effective solutions to maintain safe drinking and recreational waters. Cyanobacteria and microcystins were measured by flow cytometry and liquid chromatography coupled to tandem mass spectrometry in two interconnected reservoirs varying in age and management regimes, in southern Britain over a 12-month period. Microcystins were detected in both reservoirs, with significantly higher concentrations in the southern lake (maximum concentration >7 Āµg L-1). Elevated microcystin concentrations were not positively correlated with numbers of cyanobacterial cells, but multiple linear regression analysis suggested temperature and dissolved oxygen explained a significant amount of the variability in microcystin across both reservoirs. The presence of a managed fishery in one lake was associated with decreased microcystin levels, suggestive of top down control on cyanobacterial populations. This study supports the need to develop inclusive, multifactor holistic water management strategies to control cyanobacterial risks in freshwater bodies
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