1,721,151 research outputs found
Evidence for enhanced multi-component behaviour in Tourette syndrome - an EEG study
No full textEvidence suggests that Tourette syndrome is characterized by an increase in dopamine transmission and structural as well as functional changes in fronto-striatal circuits that might lead to enhanced multi-component behaviour integration. Behavioural and neurophysiological data regarding multi-component behaviour was collected from 15 patients with Tourette syndrome (mean age = 30.40 ± 11.10) and 15 healthy controls (27.07 ± 5.44), using the stop-change task. In this task, participants are asked to sometimes withhold responses to a Go stimulus (stop cue) and change hands to respond to an alternative Go stimulus (change cue). Different onset asynchronies between stop and change cues were implemented (0 and 300 ms) in order to vary task difficulty. Tourette patients responded more accurately than healthy controls when there was no delay between stop and change stimulus, while there was no difference in the 300 ms delay condition. This performance advantage was reflected in a smaller P3 event related potential. Enhanced multi-component behaviour in Tourette syndrome is likely based on an enhanced ability to integrate information from multiple sources and translate it into an appropriate response sequence. This may be a consequence of chronic tic control in these patients, or a known fronto-striatal networks hyperconnectivity in Tourette syndrome
Altered perceptual binding in Gilles de la Tourette syndrome
No full textGilles de la Tourette syndrome (GTS) is a common multifaceted neuropsychiatric disorder. Research in GTS has traditionally focussed on mechanisms underlying changes in motor processes in these patients. There is, however, growing interest in GTS related sensory phenomena. According to the Theory of Event-coding (TEC), sensory stimuli do not only serve representational functions but also action-related functions. In the current study, we use the TEC framework to examine whether the way perceptual features are processed is altered in GTS. The results show that basic perceptual processes differ between GTS patients and healthy controls which might be central for the understanding of this disorder. Details or features of perceptual objects were less bound in GTS suggesting that perceptual features integration is attenuated in them. Behavioural findings were unrelated to patient characteristics implying that they might represent trait abnormalities. It is possible that altered perceptual processing in GTS is due to a long-range under-connectivity of parietal areas with other brain regions repeatedly been described in these patients.</p
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
Concurrent brain responses to separate auditory and visual targets.
Full text linkIn the attentional blink, a target event (T1) strongly interferes with perception of a second target (T2) presented within a few hundred milliseconds. Concurrently, the brain's electromagnetic response to the second target is suppressed, especially a late negative-positive EEG complex including the traditional P3 wave. An influential theory proposes that conscious perception requires access to a distributed, frontoparietal global workspace, explaining the attentional blink by strong mutual inhibition between concurrent workspace representations. Often, however, the attentional blink is reduced or eliminated for targets in different sensory modalities, suggesting a limit to such global inhibition. Using functional magnetic resonance imaging, we confirm that visual and auditory targets produce similar, distributed patterns of frontoparietal activity. In an attentional blink EEG/MEG design, however, an auditory T1 and visual T2 are identified without mutual interference, with largely preserved electromagnetic responses to T2. The results suggest parallel brain responses to target events in different sensory modalities
Associative plasticity in supplementary motor area - motor cortex pathways in Tourette syndrome
No full textThe important role of the supplementary motor area (SMA) in the generation of tics and urges in Gilles de la Tourette syndrome (GTS) is underscored by an increased SMA-motor cortex (M1) connectivity. However, whether plasticity is also altered in SMA-M1 pathways is unclear. We explored whether SMA-M1 plasticity is altered in patients with Tourette syndrome. 15 patients with GTS (mean age of 33.4 years, SD = 9.9) and 19 age and sex matched healthy controls were investigated with a paired association stimulation (PAS) protocol using three transcranial magnetic stimulation (TMS) coils stimulating both M1 and the SMA. Standard clinical measures for GTS symptoms were collected. There was a significant PAS effect showing that MEP amplitudes measured in blocks during and after PAS were significantly higher compared to those in the first block. However, the degree of PAS was not differentially modulated between patients and controls as shown by a Bayesian data analysis. PAS effects in GTS correlated positively with the YGTSS motor tic severity. Plasticity previously reported to be altered in sensorimotor pathways in GTS is normal in SMA-M1 projections suggesting that the dysfunction of the SMA in GTS is not primarily related to altered plasticity in SMA-M1 connections
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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