1,720,971 research outputs found
Small-world propensity reveals the frequency specificity of resting state networks
No full textGoal: Functional connectivity (FC) is an important indicator of the brain's state in different conditions, such as rest/task or health/pathology. Here we used high-density electroencephalography coupled to source reconstruction to assess frequency-specific changes of FC during resting state. Specifically, we computed the Small-World Propensity (SWP) index to characterize network small-world architecture across frequencies. Methods: We collected resting state data from healthy participants and built connectivity matrices maintaining the heterogeneity of connection strengths. For a subsample of participants, we also investigated whether the SWP captured FC changes after the execution of a working memory (WM) task. Results: We found that SWP demonstrates a selective increase in the alpha and low beta bands. Moreover, SWP was modulated by a cognitive task and showed increased values in the bands entrained by the WM task. Conclusions: SWP is a valid metric to characterize the frequency-specific behavior of resting state networks.sponsorship: The work of L. Avanzino (PI), D. Mantini, and M. Chiappalone was partially supported by the Gossweiler Foundation. The review of this paper was arranged by Editor P. Bonato. (Gossweiler Foundation)status: Publishe
Neural oscillations during motor imagery of complex gait: an HdEEG study
No full textThe aim of this study was to investigate differences between usual and complex gait motor imagery (MI) task in healthy subjects using high-density electroencephalography (hdEEG) with a MI protocol. We characterized the spatial distribution of α- and β-bands oscillations extracted from hdEEG signals recorded during MI of usual walking (UW) and walking by avoiding an obstacle (Dual-Task, DT). We applied a source localization algorithm to brain regions selected from a large cortical-subcortical network, and then we analyzed α and β bands Event-Related Desynchronizations (ERDs). Nineteen healthy subjects visually imagined walking on a path with (DT) and without (UW) obstacles. Results showed in both gait MI tasks, α- and β-band ERDs in a large cortical-subcortical network encompassing mostly frontal and parietal regions. In most of the regions, we found α- and β-band ERDs in the DT compared with the UW condition. Finally, in the β band, significant correlations emerged between ERDs and scores in imagery ability tests. Overall we detected MI gait-related α- and β-band oscillations in cortical and subcortical areas and significant differences between UW and DT MI conditions. A better understanding of gait neural correlates may lead to a better knowledge of pathophysiology of gait disturbances in neurological diseases.sponsorship: This work was partially found by Italian Ministry of Health (Ricerca corrente), by DINOGMI (Department of Excellence framework, MUR 2018-2022), and by the National Institute of Biomedical Imaging and Bioengineering award P41 EB018783. (Italian Ministry of Health (Ricerca corrente), DINOGMI (Department of Excellence framework, MUR 2018-2022), National Institute of Biomedical Imaging and Bioengineering|P41 EB018783)status: Publishe
Assessing Neurokinematic and Neuromuscular Connectivity During Walking Using Mobile Brain-Body Imaging
Full text linkGait is a common but rather complex activity that supports mobility in daily life. It requires indeed sophisticated coordination of lower and upper limbs, controlled by the nervous system. The relationship between limb kinematics and muscular activity with neural activity, referred to as neurokinematic and neuromuscular connectivity (NKC/NMC) respectively, still needs to be elucidated. Recently developed analysis techniques for mobile high-density electroencephalography (hdEEG) recordings have enabled investigations of gait-related neural modulations at the brain level. To shed light on gait-related neurokinematic and neuromuscular connectivity patterns in the brain, we performed a mobile brain/body imaging (MoBI) study in young healthy participants. In each participant, we collected hdEEG signals and limb velocity/electromyography signals during treadmill walking. We reconstructed neural signals in the alpha (8-13 Hz), beta (13-30 Hz), and gamma (30-50 Hz) frequency bands, and assessed the co-modulations of their power envelopes with myogenic/velocity envelopes. Our results showed that the myogenic signals have larger discriminative power in evaluating gait-related brain-body connectivity with respect to kinematic signals. A detailed analysis of neuromuscular connectivity patterns in the brain revealed robust responses in the alpha and beta bands over the lower limb representation in the primary sensorimotor cortex. There responses were largely contralateral with respect to the body sensor used for the analysis. By using a voxel-wise analysis of variance on the NMC images, we revealed clear modulations across body sensors; the variability across frequency bands was relatively lower, and below significance. Overall, our study demonstrates that a MoBI platform based on hdEEG can be used for the investigation of gait-related brain-body connectivity. Future studies might involve more complex walking conditions to gain a better understanding of fundamental neural processes associated with gait control, or might be conducted in individuals with neuromotor disorders to identify neural markers of abnormal gait.sponsorship: The work was supported by the KU Leuven Special Research Fund (grant C16/15/070) and the Research Foundation Flanders (FWO) (grants G0F76.16N, G0936.16N, and EOS.30446199). MZ, GB, and CP were supported by the Chinese Scholarship Council (scholarship 201708620182), the Italian Ministry of Health (fellowship SG-2018-12368232), and the Italian Ministry of Education, University and Research ("Department of Excellence 2018-2022" initiative for the Department of Neuroscience of Padua University), respectively. (KU Leuven Special Research Fund|C16/15/070, Research Foundation Flanders (FWO)|G0F76.16N, Research Foundation Flanders (FWO)|G0936.16N, Research Foundation Flanders (FWO)|EOS.30446199, Chinese Scholarship Council|201708620182, Italian Ministry of Health|SG-2018-12368232, Italian Ministry of Education, University and Research ("Department of Excellence 2018-2022" initiative for the Department of Neuroscience of Padua University))status: Publishe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Frequency-dependent modulation of neural oscillations across the gait cycle
No full textBalance and walking are fundamental to support common daily activities. Relatively accurate characterizations of normal and impaired gait features were attained at the kinematic and muscular levels. Conversely, the neural processes underlying gait dynamics still need to be elucidated. To shed light on gait-related modulations of neural activity, we collected high-density electroencephalography (hdEEG) signals and ankle acceleration data in young healthy participants during treadmill walking. We used the ankle acceleration data to segment each gait cycle in four phases: initial double support, right leg swing, final double support, left leg swing. Then, we processed hdEEG signals to extract neural oscillations in alpha, beta, and gamma bands, and examined event-related desynchronization/synchronization (ERD/ERS) across gait phases. Our results showed that ERD/ERS modulations for alpha, beta, and gamma bands were strongest in the primary sensorimotor cortex (M1), but were also found in premotor cortex, thalamus and cerebellum. We observed a modulation of neural oscillations across gait phases in M1 and cerebellum, and an interaction between frequency band and gait phase in premotor cortex and thalamus. Furthermore, an ERD/ERS lateralization effect was present in M1 for the alpha and beta bands, and in the cerebellum for the beta and gamma bands. Overall, our findings demonstrate that an electrophysiological source imaging approach based on hdEEG can be used to investigate dynamic neural processes of gait control. Future work on the development of mobile hdEEG-based brain-body imaging platforms may enable overground walking investigations, with potential applications in the study of gait disorders.sponsorship: Chinese Scholarship Council, Grant/Award Number: 201708620182; Fonds Wetenschappelijk Onderzoek, Grant/Award Numbers: EOS.30446199, G0936.16N, G0F76.16N; Italian Ministry of Health, Grant/Award Numbers: G-2018-12368232, RF2018-12366899; KU Leuven Special Research Fund, Grant/Award Number: C16/15/070 (Chinese Scholarship Council|201708620182, Fonds Wetenschappelijk Onderzoek|EOS.30446199, Fonds Wetenschappelijk Onderzoek|G0936.16N, Fonds Wetenschappelijk Onderzoek|G0F76.16N, Italian Ministry of Health|G-2018-12368232, Italian Ministry of Health|RF2018-12366899, KU Leuven Special Research Fund|C16/15/070)status: Publishe
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Stimolazione di colture di astrociti in vitro con campi elettromagnetici a radiofrequenza
Full text linkL'elaborato analizza gli effetti in vitro di campi elettromagnetici a radiofrequenza su colture cellulari murine. Per svolgere i seguenti esperimenti e' stato utilizzato l'apparecchio Rexon-Age che, mediante correnti, provoca una stimolazione a livello cellulare. Sono stati effettuati due esperimenti, di durata diversa, che prevedevano la stimolazione a potenza nominale di 50 per 10 minuti al giorno. Il campo interferisce con la crescita cellular
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