555 research outputs found

    State power and the Colonial Mindset: Defining state legitimacy in postcolonial South Asia

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    Abstract: This paper will argue that the way in which the Pakistani and Indian states have legitimized their rule over the past sixty year is influenced by the legacy British colonialism. This case is made by analyzing and contrasting the way pre-colonial empires legitimized their rule to the British Raj. This investigation has shown that the pre-colonial empires were accompanied by an ideology that sought legitimacy exclusively through the furthering of Dharma. Dharma in the context of state power meant the promotion of “good governance” that was specifically contingent on the fulfillment by the ruler of basic forms of citizenship rights. Absent in these pre-historic documents was an emphasis on “divine rights” or “absolutist” rule that was accorded to state authorities. As such, the administrative structures in India’s pre-colonial empires were highly decentralized and boasted many measures of checks-and-balances on the power wielded by the state. On the contrary, the British ruled India through an ideology that was tinted with a Euro-centric, racialist lens. This had the effect of delegitimizing the previous form of Indian rule and promoting a political culture in which post-enlightenment ideas founded on the premises of a powerful and coercive unitary state were imported to replace the pre-colonial political system of layered and shared power. But there was embargo on the export of rights of citizens of sovereign states to Europe’s colonies. This distortion of in ideas of state power and citizenship rights has had fundamental implications in post-colonial South Asia, resulting in a crisis of political legitimization that has plagued the Indian and Pakistani state for the past 60 years. Since this analysis has shown how ideas and discourse can affect the way states legitimize their rule, this paper concludes by arguing that the path to progress for both nations lies in undergoing an ideational shift in the way the states have legitimized their rule

    The perioperative use of oral anticoagulants during surgical procedures for carpal tunnel syndrome. A preliminary study

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    Contains fulltext : 87781.pdf (publisher's version ) (Closed access)BACKGROUND: To evaluate the feasibility of designing a randomized controlled study whether open carpal tunnel release (OCTR) surgery can be performed safely under systemic anticoagulant therapy using acetylsalicylacid (ASA) or acenocoumarol (ACM), this preliminary, observational study was performed. METHODS: Prospectively, during 1 year, data were collected from all patients who underwent conventional OCTR at the neurosurgical department of the Canisius Wilhelmina Hospital, Nijmegen, The Netherlands. Patients continued anticoagulant treatment perioperatively. RESULTS: A total of 364 patients were operated on, of whom 45 continued ASA and seven ACM treatment. Only one patient using ASA complained of a postoperative subcutaneous hemorrhage. In the control group without anticoagulants, none of the patients had a bleeding postoperatively. CONCLUSION: Continuation of anticoagulant treatment is safe for OCTR. The adverse effects of stopping treatment for surgery can be severe. As a result of this study, we have changed our surgery protocol for OCTR and continue anticoagulant treatment perioperatively.1 juli 201

    On the validity of neural mass models

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    FUNDING This study received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement #642563 (COSMOS). ACKNOWLEDGMENTS ND and AD want to thank Rok Cestnik and Bastian Pietras for fruitful discussionsPeer reviewedPublisher PD

    Structure-function relationships in the visual system in multiple sclerosis: an MEG and OCT study

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    BACKGROUND: We conducted a multi-modal optical coherence tomography (OCT) and magnetoencephalography (MEG) study to test whether there is a relationship between retinal layer integrity and electrophysiological activity and connectivity (FC) in the visual network influenced by optic neuritis (ON) in patients with multiple sclerosis (MS). METHODS: One hundred and two MS patients were included in this MEG/OCT study. Retinal OCT data were collected from the optic discs, macular region, and segmented. Neuronal activity and FC in the visual cortex was estimated from source-reconstructed resting-state MEG data by computing relative power and the phase lag index (PLI). Generalized estimating equations (GEE) were used to account for intereye within-patient dependencies. RESULTS: There was a significant relationship for both relative power and FC in the visual cortex with retinal layer thicknesses. The findings were influenced by the presence of MSON, particularly for connectivity in the alpha bands and the outer macular layers. In the absence of MSON, this relationship was dominated by the lower frequency bands (theta, delta) and inner and outer retinal layers. CONCLUSION: These results suggest that visual cortex FC more than activity alters in the presence of MSON, which may guide the understanding of FC plasticity effects following MSON

    Measuring electrophysiological connectivity by power envelope correlation: a technical review on MEG methods

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    The human brain can be divided into multiple areas, each responsible for different aspects of behaviour. Healthy brain function relies upon efficient connectivity between these areas and, in recent years, neuroimaging has been revolutionised by an ability to estimate this connectivity. In this paper we discuss measurement of network connectivity using magnetoencephalography (MEG), a technique capable of imaging electrophysiological brain activity with good (~5mm) spatial resolution and excellent (~1ms) temporal resolution. The rich information content of MEG facilitates many disparate measures of connectivity between spatially separate regions and in this paper we discuss a single metric known as power envelope correlation. We review in detail the methodology required to measure power envelope correlation including i) projection of MEG data into source space, ii) removing confounds introduced by the MEG inverse problem and iii) estimation of connectivity itself. In this way, we aim to provide researchers with a description of the key steps required to assess envelope based functional networks, which are thought to represent an intrinsic mode of coupling in the human brain. We highlight the principal findings of the techniques discussed, and furthermore, we show evidence that this method can probe how the brain forms and dissolves multiple transient networks on a rapid timescale in order to support current processing demand. Overall, power envelope correlation offers a unique and verifiable means to gain novel insights into network coordination and is proving to be of significant value in elucidating the neural dynamics of the human connectome in health and disease

    Optimising experimental design for MEG resting state functional connectivity measurement

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    The study of functional connectivity using magnetoencephalography (MEG) is an expanding area of neuroimaging, and adds an extra dimension to the more common assessments made using fMRI. The importance of such metrics is growing, with recent demonstrations of their utility in clinical research, however previous reports suggest that whilst group level resting state connectivity is robust, single session recordings lack repeatability. Such robustness is critical if MEG measures in individual subjects are to prove clinically valuable. In the present paper, we test how practical aspects of experimental design affect the intra-subject repeatability of MEG findings; specifically we assess the effect of co-registration method and data recording duration. We show that the use of a foam head-cast, which is known to improve co-registration accuracy, increased significantly the between session repeatability of both beamformer reconstruction and connectivity estimation. We also show that recording duration is a critical parameter, with large improvements in repeatability apparent when using ten minute, compared to five minute recordings. Further analyses suggest that the origin of this latter effect is not underpinned by technical aspects of source reconstruction, but rather by a genuine effect of brain state; short recordings are simply inefficient at capturing the canonical MEG network in a single subject. Our results provide important insights on experimental design and will prove valuable for future MEG connectivity studies

    How do spatially distinct frequency specific MEG networks emerge from one underlying structural connectome? The role of the structural eigenmodes

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    Functional networks obtained from magnetoencephalography (MEG) from different frequency bands show distinct spatial patterns. It remains to be elucidated how distinct spatial patterns in MEG networks emerge given a single underlying structural network. Recent work has suggested that the eigenmodes of the structural network might serve as a basis set for functional network patterns in the case of functional MRI. Here, we take this notion further in the context of frequency band specific MEG networks. We show that a selected set of eigenmodes of the structural network can predict different frequency band specific networks in the resting state, ranging from delta (1–4 Hz) to the high gamma band (40–70 Hz). These predictions outperform predictions based from surrogate data, suggesting a genuine relationship between eigenmodes of the structural network and frequency specific MEG networks. We then show that the relevant set of eigenmodes can be excited in a network of neural mass models using linear stability analysis only by including delays. Excitation of an eigenmode in this context refers to a dynamic instability of a network steady state to a spatial pattern with a corresponding coherent temporal oscillation. Simulations verify the results from linear stability analysis and suggest that theta, alpha and beta band networks emerge very near to the bifurcation. The delta and gamma bands in the resting state emerges further away from the bifurcation. These results show for the first time how delayed interactions can excite the relevant set of eigenmodes that give rise to frequency specific functional connectivity patterns

    Abnormal task driven neural oscillations in multiple sclerosis: a visuomotor MEG study

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    Multiple sclerosis (MS) is a debilitating disease commonly attributed to degradation of white matter myelin. Symptoms include fatigue, as well as problems associated with vision and movement. Although areas of demyelination in white matter are observed routinely in patients undergoing MRI scans, such measures are often a poor predictor of disease severity. For this reason, it is instructive to measure associated changes in brain function. Widespread white-matter demyelination may lead to delays of propagation of neuronal activity, and with its excellent temporal resolution, magnetoencephalography can be used to probe such delays in controlled conditions (e.g., during a task). In healthy subjects, responses to visuomotor tasks are well documented: in motor cortex, movement elicits a localised decrease in the power of beta band oscillations (event-related beta desynchronisation) followed by an increase above baseline on movement cessation (post-movement beta rebound (PMBR)). In visual cortex, visual stimulation generates increased gamma oscillations. In this study, we use a visuomotor paradigm to measure these responses in MS patients and compare them to age- and gender-matched healthy controls. We show a significant increase in the time-to-peak of the PMBR in patients which correlates significantly with the symbol digit modalities test: a measure of information processing speed. A significant decrease in the amplitude of visual gamma oscillations in patients is also seen. These findings highlight the potential value of electrophysiological imaging in generating a new understanding of visual disturbances and abnormal motor control in MS patients
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