1,720,963 research outputs found
Selective effects of a brain tumor on the metric representation of the hand: a pre- versus post-surgery comparison
Full text linkBody representation disorders are complex, varied, striking, and very disabling in most cases. Deficits of body representation have been described after lesions to multimodal and sensorimotor cortical areas. A few studies have reported the effects of tumors on the representation of the body, but little is known about the changes after tumor resection. Moreover, the impact of brain lesions on the hand size representation has been investigated in few clinical cases. Hands are of special importance, as no other body part has the ability for movement and interaction with the environment that the hands have, and we use them for a multitude of daily activities. Studies with clinical population can add further knowledge into the way hands are represented. Here, we report a single case study of a patient (AM) who was an expert bodybuilder and underwent a surgery to remove a glioblastoma in the left posterior prefrontal and precentral cortex at the level of the hand’s motor region. Pre- (20 days) and post- (4 months) surgery assessment did not show any motor or cognitive impairments. A hand localization task was used, before and after surgery (12 months), to measure possible changes of the metric representation of his right hand. Results showed a post-surgery modulation of the typically distorted hand representation, with an overall accuracy improvement, especially on width dimension. These findings support the direct involvement of sensorimotor areas in the implicit representation of the body size and its relevance on defining specific size representation dimensions
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
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
SMA-like syndrome without SMA lesion: Patterns of structural and functional disconnection in a relapsing low grade glioma
No full textIntroduction: Supplementary Motor Area syndrome (SMAs), a severe but transient syndrome inducing contralateral akinesia and language deficits, typically arises from lesion involving the Supplementary Motor Area (SMA). Through a functional and structural disconnection approach, we investigated whether lesion-related neuropsychological symptoms could be explained in terms of hodotopical loss of integrity across the whole-brain connectome. Method: We report a case of a 53-year-old man who underwent resection of the left lateral inferior frontal gyrus, as well as the middle and superior frontal gyri for a low-grade glioma recurrence. Although without SMA lesion, he developed SMA syndrome symptoms, including speech arrest and perseverations, the patient recovered quickly but partially. The resection cavities from the first and second surgery were used as seeds to investigate structurally and functionally disconnected circuits in a Lesion Network Mapping (LNM) analysis. As a control, SMA-complex region was included in LNM analysis. Results: Structural disconnection analysis revealed common disconnections between second surgery resection cavity and SMA region, at the level of the Cingulate and Superior Longitudinal Fasciculus. Also, functional analysis showed greater second surgery induced disconnection in critical hubs of the Fronto-Parietal and Default Mode Networks, as well as functional disconnection involving the spared SMA complex. Discussion: Here the SMA syndrome, emerged despite no SMA lesion, appears to results from an alteration of structural and functional brain circuits, according to the hodotopical theory. We can speculate that disruption of interconnected networks may underlie symptom manifestation in SMA syndrome and may offer a potential framework for studying disconnection-related mechanisms. (c) 2025 Published by Elsevier Ltd
rTMS of Medial Parieto-occipital Cortex Interferes with Attentional Reorienting during Attention and Reaching Tasks
No full textUnexpected changes in the location of a target for an upcoming action require both attentional reorienting and motor planning update. In both macaque and human brain, the medial posterior parietal cortex is involved in both phenomena but its causal role is still unclear. Here we used on-line rTMS over the putative human V6A (pV6A), a reach-related region in the dorsal part of the anterior bank of the parietooccipital sulcus, during an attention and a reaching task requiring covert shifts of attention and planning of reaching movements toward cued targets in space. We found that rTMS increased RTs to invalidly cued but not to validly cued targets during both the attention and reaching task. Furthermore, we found that rTMS induced a deviation of reaching endpoints toward visual fixation and that this deviation was larger for invalidly cued targets. The results suggest that reorienting signals are used by human pV6A area to rapidly update the current motor plan or the ongoing action when a behaviorally relevant object unexpectedly occurs in an unattended location. The current findings suggest a direct involvement of the actionrelated dorso-medial visual stream in attentional reorienting and a more specific role of pV6A area in the dynamic, on-line control of reaching actions
The Interhemispheric Transgenual Approach for Microsurgical Removal of Third Ventricle Colloid Cysts. Technical Note
No full textBackground: Colloid cysts of the third ventricle are rare benign lesions, which amount to approximately 1% of all intracranial tumors. Because these lesions grow predominantly in the anterior aspect of the third ventricle, they may cause the occlusion of the foramina of Monro, generating obstructive hydrocephalus. Surgery is mandatory in cases of large cysts and/or in symptomatic patients. Among the different surgical strategies described in colloid cysts surgery, the microsurgical transcallosal approach still constitutes the procedure of choice in many centers. In this study, we describe a modified microsurgical transcallosal approach, the interhemispheric transgenual approach, in a series of 13 consecutive patients operated on for colloid cysts of the third ventricle. Methods: All the procedures were performed by the senior author (V.E.) at Neuromed Institute of Pozzilli (Is, Italy). The operative procedure is described in its various steps, illustrating the differences and potential advantages compared with the traditional microsurgical transcallosal approach. Results: No surgical complications or new-onset neurologic deficits were observed in the postoperative period. The postoperative magnetic resonance imaging confirmed in all cases complete lesion removal without any sign of parenchymal damage. No lesion recurrence or need for permanent cerebrospinal fluid diversion was detected in the patients of this series during the follow-up period. Conclusions: In our experience, the interhemispheric transgenual approach has been effective in providing complete colloid cyst removal with minimal risk of vascular and parenchymal damage. Further studies are required to confirm its efficacy in improving the overall outcome of the microsurgical transcallosal approach
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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