1,721,025 research outputs found
Resting-state retinotopic organization in the absence of retinal input and visual experience
Get PDFEarly visual areas have neuronal receptive fields that form a sampling mosaic of visual space, resulting in a series of retinotopic maps in which the same region of space is represented in multiple visual areas. It is not clear to what extent the development and maintenance of this retinotopic organization in humans depend on retinal waves and/or visual experience. We examined the corticocortical receptive field organization of resting-state BOLD data in normally sighted, early blind, and anophthalmic (in which both eyes fail to develop) individuals and found that resting-state correlations between V1 and V2/V3 were retinotopically organized for all subject groups. These results show that the gross retinotopic pattern of resting-state connectivity across V1-V3 requires neither retinal waves nor visual experience to develop and persist into adulthood.
SIGNIFICANCE STATEMENT Evidence from resting-state BOLD data suggests that the connections between early visual areas develop and are maintained even in the absence of retinal waves and visual experience
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
Enhancing speech fluency using transcranial direct current stimulation
Get PDFProducing speech is a highly complex task, involving the integration of sensory and linguistic information, with the precise, high-speed, co-ordination of muscles controlling breathing and the movement of the vocal folds and articulators. In spite of this complexity, producing fluent speech â moving smoothly from one speech sound to the next â can appear effortless. Speech fluency is highly socially valued, and the personal and societal costs of living with a disorder of fluency, such as developmental stuttering, are considerable. The outcomes of behavioural therapies to increase fluency are limited, however, especially for those seeking treatment in adulthood.
The overarching aim of this thesis was to investigate how anodal transcranial direct current stimulation (A-TDCS) can be used to increase speech fluency, with a particular focus on the potential application to developmental stuttering. A-TDCS is a noninvasive brain stimulation technique that can enhance the effects of motor, speech, and language training.
First, in a series of single-session experiments in typically fluent speakers, I demonstrated that applying A-TDCS over the left IFC increased speech motor learning relative to a sham control, but did not improve consolidation of this learning (chapter 2). Furthermore, I found that neither increasing stimulation intensity from 1 mA to 2 mA, nor changing from a unihemispheric to a bihemispheric configuration, had an additional effect on learning.
Next, in single-session study with adults who stutter, I assessed the feasibility of using A-TDCS to improve fluency (chapter 3). Fluency was temporarily induced, by speaking in unison with another person, but the concurrent application of 1-mA unihemispheric A-TDCS over left inferior frontal cortex did not significantly prolong this fluency. Nevertheless, a trend towards stuttering reduction gave some indication that fluency might be increased using a multiple-session approach. Furthermore, I gained a number of important insights from these single-session studies, which I used to inform the design of the final multiple-session trial.
In this final study, I completed a randomised controlled trial in 30 adult males with moderate to severe stuttering. Participants were randomized to receive either 1-mA A-TDCS or sham stimulation over left inferior frontal cortex combined with temporary fluency inducing behavioural techniques, for 20 minutes a day over 5 days (chapter 4). A-TDCS significantly reduced disfluency for at least 5 weeks following this intervention. The effect was specific to the speech impairment of development stuttering, as measures of the psycho-social consequences of stuttering were not modulated by A-TDCS.
The findings of these studies offer significant promise for the future application of non-invasive stimulation as an adjunctive therapy for adults who stutter. In the concluding chapter, I discuss the important implications of my findings for the future use of this technique.</p
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
Investigating the effects of visual deprivation on subcortical and cortical structures using functional MRI and MR spectroscopy
Get PDFVisual deprivation in early life causes widespread changes to the visual pathway. Structures normally dedicated to vision can be recruited for processing of the remaining senses (i.e. audition). This thesis used magnetic resonance imaging to explore how the 'visual' pathway reorganises in congenital bilateral anophthalmia, a condition where individuals are born without eyes. Anophthalmia provides a unique model of complete deprivation, since the ‘visual’ pathway has not experienced pre- or post-natal visual input. Firstly, this thesis explored reorganisation of the anophthalmic 'visual' pathway for auditory processing, from subcortical structures responding to basic sounds (Chapters 3 and 4), to higher-order occipital areas extracting meaning from speech sounds (Chapter 7). Secondly, this thesis looked to better understand the neurochemical, neuroanatomical and behavioural changes that accompany reorganisation in anophthalmia (Chapters 5 and 6). Finally, this thesis investigated whether similar changes can take place in the sighted brain after a short period of visual deprivation (Chapter 8). The experiments in this thesis provide some evidence that the lack of pre-natal visual experiences affects cross-modal reorganisation. Chapter 4 describes a unique subcortico-cortical route for auditory input in anophthalmia. Furthermore, Chapter 7 suggests that hierarchical processing of sensory information in the occipital cortex is maintained in anophthalmia, which may not be the case in congenital or early-onset blindness. However, this thesis also suggests that some reorganisation thought to be limited to anophthalmia can be found in early-onset blindness, for example with the subcortical functional changes described in Chapter 3. In addition, neurochemical, neuroanatomical and behavioural changes described in Chapters 5 and 6 are comparable to those reported in early-onset blindness, therefore demonstrating important similarities between these populations. Finally, this thesis describes how some of these functional and behavioural changes can also take place in sighted subjects after a short period of blindfolding, although this effect is extremely variable across subjects (Chapter 8). The thesis concludes by highlighting the considerable contribution of individual differences in studies of cross-modal reorganisation, and emphasises the need for larger more homogenous groups when investigating subcortical and cortical plasticity in the absence of visual input
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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