Differences in MEG and EEG power-law scaling explained by a coupling between spatial coherence and frequency: a simulation study

International audienceElectrophysiological signals (electroencephalography, EEG, and magnetoencephalography , MEG), as many natural processes, exhibit scale-invariance properties resulting in a power-law (1/f) spectrum. Interestingly, EEG and MEG differ in their slopes, which could be explained by several mechanisms, including non-resistive properties of tissues. Our goal in the present study is to estimate the impact of space/frequency structure of source signals as a putative mechanism to explain spectral scaling properties of neuroimaging signals. We performed simulations based on the summed contribution of cortical patches with different sizes (ranging from 0.4 to 104.2 cm 2). Small patches were attributed signals of high frequencies, whereas large patches were associated with signals of low frequencies, on a logarithmic scale. The tested parameters included i) the space/frequency structure (range of patch sizes and frequencies) and ii) the amplitude factor c parametrizing the spatial scale ratios. We found that the space/frequency structure may cause differences between EEG and MEG scale-free spectra that are compatible with real data findings reported in previous studies. We also found that below a certain spatial scale, there were no more differences between EEG and MEG, suggesting a limit for the resolution of both methods. Our work provides an explanation of experimental findings. This does not rule out other mechanisms for differences between EEG and MEG, but suggests an important role of spatio-temporal structure of neural dynamics. This can help the analysis and interpretation of power-law measures in EEG and MEG, and we believe our results can also impact computational modeling of brain dynamics, where different local connectivity structures could be used at different frequencies

Archives that Matter: Infrastructures for Sharing Unshared Histories. An Introduction

Introductio

O acesso à cultura: uma solução de relações públicas na era dos social media

Trabalho de projeto apresentado à Escola Superior de Comunicação Social como parte dos requisitos para obtenção de grau de mestre em Gestão Estratégica das Relações Públicas.O presente trabalho tem como objetivo enriquecer os estudos de comunicação sobre o setor cultural através de uma perspetiva no âmbito da Gestão Estratégica das Relações Públicas. Partindo de uma revisão de literatura sobre o conceito de cultura e eventos e práticas culturais, as Relações Públicas, percorrendo a sua evolução histórica até aos desafios e oportunidades na hegemonia do mundo digital dos dias de hoje, apresenta-se uma proposta de plataforma online que permite melhorar a comunicação entre organizações culturais e os seus públicos. Utiliza-se o modelo em quatro etapas para a investigação, conceção e desenvolvimento do projeto e mostra-se a sua pertinência para uma comunicação bidirecional entre organizações culturais e públicos.ABSTRACT: The present paper has the goal to improve the communication studies of cultural sector through a perspective of Public Relations Management. Throughout a literature review of culture concept, events, cultural practices and Public Relations, this paper presents a proposal of an online platform to improve digital communication between cultural organizations and its publics, allowing a two-way communication. Cutlip et al. Four Step Public Relations Process model is used for the project’s research, action, communication and evaluation.N/

Detection and Magnetic Source Imaging of Fast Oscillations (40–160 Hz) Recorded with Magnetoencephalography in Focal Epilepsy Patients

We present a framework to detect fast oscillations (FOs) in magnetoencephalography (MEG) and to perform magnetic source imaging (MSI) to determine the location and extent of their generators in the cortex. FOs can be of physiologic origin associated to sensory processing and memory consolidation. In epilepsy, FOs are of pathologic origin and biomarkers of the epileptogenic zone. Seventeen patients with focal epilepsy previously confirmed with identified FOs in scalp electroencephalography (EEG) were evaluated. To handle data deriving from large number of sensors (275 axial gradiometers) we used an automatic detector with high sensitivity. False positives were discarded by two human experts. MSI of the FOs was performed with the wavelet based maximum entropy on the mean method. We found FOs in 11/17 patients, in only one patient the channel with highest FO rate was not concordant with the epileptogenic region and might correspond to physiologic oscillations. MEG FOs rates were very low: 0.02–4.55 per minute. Compared to scalp EEG, detection sensitivity was lower, but the specificity higher in MEG. MSI of FOs showed concordance or partial concordance with proven generators of seizures and epileptiform activity in 10/11 patients. We have validated the proposed framework for the non-invasive study of FOs with MEG. The excellent overall concordance with other clinical gold standard evaluation tools indicates that MEG FOs can provide relevant information to guide implantation for intracranial EEG pre-surgical evaluation and for surgical treatment, and demonstrates the important added value of choosing appropriate FOs detection and source localization methods.Facultad de IngenieríaInstituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

Immunogenicity of a Promiscuous T Cell Epitope Peptide Based Conjugate Vaccine against Benzo[a]pyrene: Redirecting Antibodies to the Hapten

The prototype polycyclic aromatic hydrocarbon benzo[a]pyrene (B[a]P) is an environmental pollutant and food contaminant of epidemiological importance. To protect against adverse effects of this ubiquitous carcinogen, we developed an immunoprophylactic strategy based on a B[a]P-protein conjugate vaccine to induce B[a]P specific antibodies (Grova et al., Vaccine. 2009;27:4142–51). Here, we investigated in mice the efficacy of B[a]P-peptide conjugates based on promiscuous T cell epitopes (TCE) into further improve this approach. We showed that B[a]P-peptide conjugates induced very different levels of hapten-specific antibodies with variable functional efficacy, depending on the carrier. In some cases peptide carriers induced a more efficient antibody response against B[a]P than tetanus toxoid as a protein carrier, with the capacity to sequester more B[a]P in the blood. Reducing the carrier size to a single TCE can dramatically shift the antibody bias from the carrier to the B[a]P. Conjugates based on the TCE FIGITEL induced the best anti-hapten response and no antibodies against the carrier peptide. Some peptide conjugates increased the selectivity of the antibodies for the activated metabolite 7,8-diol-B[a]P and B[a]P by one or two orders of magnitude. The antibody efficacy was also demonstrated in their ability to sequester B[a]P in the blood and modulate its faecal excretion (15–56%). We further showed that pre-existing immunity to the carrier from which the TCE was derived did not reduce the immunogenicity of the peptide conjugate. In conclusion, we showed that a vaccination against B[a]P using promiscuous TCEs of tetanus toxin as carriers is feasible even in case of a pre-existing immunity to the toxoid and that some TCE epitopes dramatically redirect the antibody response to the hapten. Further studies to demonstrate a long-term protection of an immunoprophylactic immunisation against B[a]P are warranted

SMS as a learning tool: an experimental study

[EN] The aim of this experimental study was to find out the potential of using mobile phones in teaching English as a foreign language, specifically the use of SMS as a support tool in the EFL class. The research questions formulated were: (1) Is using SMS messages via a mobile phone an effective tool in terms of motivation and engagement? (2) What type of mini-lessons do subjects think are better to be sent via SMS in terms of effectiveness, engagement, and usefulness for their learning purposes? (3) What is the appropriate timing for the activities to be sent? (4) Did students who participated in the project perform better than the control group? This experimental study lasted two academic years. As this was a preliminary study of the viability of the SMS methodology, it was conducted with a small group of students (n=13) from the English Degree at the University Rovira i Virgili (Tarragona, Spain). During the first year we designed various types of activities and sent them though a period of 15 weeks. The aim of this first part was to answer the research questions 1 to 3. The second year, a new set of exercises was created. This time, the aim was to gather data to be able to answer the fourth research question. Both qualitative data (from the first year) and quantitative data (from the second year) were analysed. We can conclude that the subjects have found this experience engaging. The subjects preferred receiving short, direct exercises which could be answered immediately. They preferred receiving the SMS in the afternoon or evening and the results show that this methodology enhances the retrieval of memorized English language rules. The results of this study were presented at the EuroCALL 2011 conference in Nottingham and are the result of a research project funded by the Institut de Ciències de l'Educació (Universitat Rovira i Virgili).Gutiérrez-Colon Plana, M.; Gallardo Torrano, P.; Grova, ME. (2012). SMS as a learning tool: an experimental study. The EuroCALL Review. 20(2):33-47. https://doi.org/10.4995/eurocall.2012.11376SWORD3347202Cavus, N. and Ibrahim, D. (2009). M-Learning: An experiment using SMS to support learning new English language words. British Journal of Educational Technology, Vol. 40, No. 1: 78-91. https://doi.org/10.1111/j.1467-8535.2007.00801.xChurchill, D. and Hedberg, J. (2008). Learning objects design considerations for small-screen handheld devices. Computers and Education, 50: 881-893. https://doi.org/10.1016/j.compedu.2006.09.004Cornelius,S., Marston, Ph. and Gemmell, A. (2011). SMS text messaging for real-ime simulations in Higher Education. In Traxler and Wishart, J. 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Journal of Learning Design, 2: 52-65. https://doi.org/10.5204/jld.v2i1.28Levy, M. and Kennedy, C. (2005). Learning Italian via mobile SMS. In A. Kukulshka-Hulme and J. Traxler (eds.), Mobile Learning: A handbook for educators and trainers. London: Routledge. 76-83.Lu M. (2008). Efectiveness of vocabulary learning via mobile phone. Journal of Computer Assisted Learning, 24: 515-525. https://doi.org/10.1111/j.1365-2729.2008.00289.xPownell, D. and Bailey, G. (2001). Getting a handle on handhelds: what to consider before you introduce handheld computers in your school. American School Board Journal.So, S. (2009). The development of a SMS-based teaching and learning system. Journal of Educational Technology Development and Exchange, 21(1): 113-124. https://doi.org/10.18785/jetde.0201.08Stockwell, G. (2007). Vocabulary on the Move: Investigating an intelligent mobile phone-based vocabulary tutor. Computer Assisted Language Learning. Vol. 20, No. 4: 365-383. https://doi.org/10.1080/09588220701745817Stockwell, G. (2010). Using Mobeil Phones fror Vocabulary Activities: Examining the Effect of the Platform. Language Learning and Technology, Vol 14, No. 2: 95-110.Thornton, P. and Houser, C. (2001). Learning on the move: Vocabulary study via e-mail and mobile phone SMS. In C. Montgomerie and J. Viteli (eds.), Proceedings of World Conference on Educational Multimedia, Hypermedia and Telecommunications 2001. Chesapeake, VA: AACE. 1896-1897.Thornton, P. and Houser, C. (2005). Using mobile phones in English Education in Japan. Journal of Computer Assisted Learning , 21: 217-228 https://doi.org/10.1111/j.1365-2729.2005.00129.xTraxler, J. (2009). Learning in a Mobile Age. International Journal of Mobile and Blended Learning 1(1): 1-12. https://doi.org/10.4018/jmbl.2009010101Vavoula, G. and Sharples, M. (2009). Meeting the challenges in evaluating mobile learning: A 3-level evaluation framework. 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