1,721,043 research outputs found
An Introduction to EEG/MEG for Model-Based Cognitive Neuroscience
Get PDFElectroencephalography (EEG) and magnetoencephalography (MEG) are closely related non-invasive recording techniques that are of great value in cognitive neuroscience studies with human participants. They are sensitive to, respectively, changes in electric and magnetic fields that are generated by post-synaptic currents on spatially aligned pyramidal cells in cortex. The superior time resolution of EEG/MEG compared to functional magnetic resonance imaging (fMRI) allows for tracking changes in neural activity during the subject’s perfor-mance of a behavioural task with high temporal precision. This chapter introduces the biophysics behind EEG/MEG recordings, discusses practical issues when conducting an experiment, and highlights the most important signal features for the field of cognitive neuroscience. Furthermore, it illustrates how the combination of cognitive modelling and EEG/MEG may aid a meaningful interpretation of experimental findings.</p
Discovering Cognitive Stages in M/EEG Data to Inform Cognitive Models
Get PDFComputational cognitive models aim to simulate the cognitive processes humans go through when performing a particular task. In this chapter, we discuss a machine learning approach that can discover such cognitive processes in M/EEG data. The method uses a combination of multivariate pattern analysis (MVPA) and hidden semi-Markov models (HsMMs), to take both the spatial extent and the temporal duration of cognitive processes into account. In the first part of this chapter, we will introduce the HsMM-MVPA method and demonstrate its application to an associative recognition dataset. Next, we will use the results of the analysis to inform a high-level cognitive model developed in the ACT-R (adaptive control of thought – rational) architecture. Finally, we will discuss how the HsMM-MVPA method can be extended and how it can inform other modeling paradigms.</p
Commentary:Transcranial stimulation of the frontal lobes increases propensity of mind-wandering without changing meta-awareness
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Transcranial stimulation of the frontal lobes increases propensity of mind-wandering without changing meta-awareness
by Axelrod, V., Zhu, X., & Qui, J. (2018). Scientific Reports, 8:15975. doi: 10.1038/s41598-018-34098-
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Reliability of triggering the stop process is related to prefrontal-subthalamic hyperdirect pathway recruitment
Get PDFThe estimated latency of the unobservable stop response, the so-called stop-signal reaction time (SSRT), has been the established measure of performance in the stop-signal task. While it is currently debated whether SSRT is a suitable marker of inhibition performance, other markers such as the reliability of triggering the stop process (“stop trigger failures”) are coming into focus. In the present study, we elucidated the mechanisms associated with trigger failures using a model-based neuroscience approach by means of functional magnetic resonance imaging for the first time. To this end, we used a large, open-access fMRI data set to investigate the relationship between the probability of trigger failures and fMRI signal change in a stop-signal task in healthy adults (n = 113). Stop trigger failures were associated with less activity in the substantia nigra during unsuccessful stopping and with less activity in the subthalamic nucleus (STN) region during successful inhibition. Although stop trigger failures strongly correlated with SSRT, we found only little evidence for a correlation between SSRT and stopping-related fMRI signal. Thus, in particular, the reliability of the stop process and not its estimated latency depends on the recruitment of key nodes within the prefrontal-subthalamic hyperdirect pathway. More specifically, stop trigger failures may be linked to inadequate substantia nigra innervation at the neural network level. As current evidence suggests that the hyperdirect pathway is engaged by the processing of salient stimuli, deficiencies in assessing the relevance of the stop signal may represent a phenotype associated with a propensity to trigger the stop process unreliably.</p
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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