23 research outputs found

    One session of fMRI-Neurofeedback training on motor imagery modulates whole-brain effective connectivity and dynamical complexity

    Get PDF
    In the past decade, several studies have shown that Neurofeedback (NFB) by functional magnetic resonance imaging can alter the functional coupling of targeted and non-targeted areas. However, the causal mechanisms underlying these changes remain uncertain. Here, we applied a whole-brain dynamical model to estimate Effective Connectivity (EC) profiles of resting-state data acquired before and immediately after a single-session NFB training for 17 participants who underwent motor imagery NFB training and 16 healthy controls who received sham feedback. Within-group and between-group classification analyses revealed that only for the NFB group it was possible to accurately discriminate between the 2 resting-state sessions. NFB training-related signatures were reflected in a support network of direct connections between areas involved in reward processing and implicit learning, together with regions belonging to the somatomotor, control, attention, and default mode networks, identified through a recursive-feature elimination procedure. By applying a data-driven approach to explore NFB-induced changes in spatiotemporal dynamics, we demonstrated that these regions also showed decreased switching between different brain states (i.e. metastability) only following real NFB training. Overall, our findings contribute to the understanding of NFB impact on the whole brain's structure and function by shedding light on the direct connections between brain areas affected by NFB training

    Maternal mortality in the rural Gambia, a qualitative study on access to emergency obstetric care

    Get PDF
    BACKGROUND: Maternal mortality is the vital indicator with the greatest disparity between developed and developing countries. The challenging nature of measuring maternal mortality has made it necessary to perform an action-oriented means of gathering information on where, how and why deaths are occurring; what kinds of action are needed and have been taken. A maternal death review is an in-depth investigation of the causes and circumstances surrounding maternal deaths. The objectives of the present study were to describe the socio-cultural and health service factors associated with maternal deaths in rural Gambia. METHODS: We reviewed the cases of 42 maternal deaths of women who actually tried to reach or have reached health care services. A verbal autopsy technique was applied for 32 of the cases. Key people who had witnessed any stage during the process leading to death were interviewed. Health care staff who participated in the provision of care to the deceased was also interviewed. All interviews were tape recorded and analyzed by using a grounded theory approach. The standard WHO definition of maternal deaths was used. RESULTS: The length of time in delay within each phase of the model was estimated from the moment the woman, her family or health care providers realized that there was a complication until the decision to seeking or implementing care was made. The following items evolved as important: underestimation of the severity of the complication, bad experience with the health care system, delay in reaching an appropriate medical facility, lack of transportation, prolonged transportation, seeking care at more than one medical facility and delay in receiving prompt and appropriate care after reaching the hospital. CONCLUSION: Women do seek access to care for obstetric emergencies, but because of a variety of problems encountered, appropriate care is often delayed. Disorganized health care with lack of prompt response to emergencies is a major factor contributing to a continued high mortality rate

    A quantitative evaluation of damage in normal appearing white matter in patients with multiple sclerosis using diffusion tensor MR imaging at 3 T

    No full text
    The white matter (WM) of the brain is damaged in multiple sclerosis (MS), even in areas that appear normal on standard MR imaging. The purpose of our study is to evaluate the damage of normal appearing white matter (NAWM) in patients with MS. In our study, 84 MS patients and 42 healthy adults underwent a routine brain MRI, including also diffusion tensor imaging (DTI). All studies were performed on a 3 T MRI scanner. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were obtained. The DTI parameters of NAWM were correlated with expanded disability status scales (EDSS) scores. Our results showed statistically significant differences in FA and ADC values between MS plaques and the symmetrical NAWM, as also between NAWM and the respective white matter in controls. The ADC values of the NAWM correlated with the EDSS scores. The present study demonstrated damage of the NAWM in MS patients, using DTI in 3.0 T. DTI may be used in the detection of subtle damage of the white matter

    Firm networks: external relationships as sources for the growth and competitiveness of entrepreneurial firms

    No full text
    Inter-firm networks, as an inter-organizational form, are increasingly perceived as a model for entrepreneurial firm growth. We study egocentric networks of high-growth entrepreneurial firms in the IT industry and explore how these firms grow through the use of external relations and become competitive. Based on case study research, we identify that firms are using relations for a variety of purposes and that every firm has an individual relational mix. This relational mix changes with the development of the firms. While the relative importance of social and reputational networks decrease with the firms' development, co-opetition networks increase over time. Knowledge and innovation networks are a function of reputation and management capacity while the development of marketing networks depends on the firm's culture and management style. Both weak ties and strong ties are important for the growth of the firm since they fulfil different functions. Firm growth is determined by path-dependent relational capability that eventually reaches its limits and leads to the reconfiguration of a rather stable network. Additionally, firm growth depends not only on the building of egocentric networks but also on the existence and development of healthy sociocentric networks
    corecore