1,720,990 research outputs found
Dissociation between contour-based and Texture-based Shape Perception: a single case study.
Full text linkA single case study of a patient suffering from a temporo-parietal lesion is presented. He was impaired at recognizing shape on the basis of texture information, whereas shape recognition on the basis of contours seemed comparatively preserved. To investigate the impaired level in texture processing, we used two alternative forced-choice tasks to test figure-ground segregation based on textural differences in contrasting modalities (tactile vs. visual) and viewing conditions (static vs. apparently moving stimuli). The results showed that the deficit was specific to visual stimuli (both static and dynamic). Moreover, this deficit did not occur with local texture analysis, but was always present in global texture segregation tasks. This suggests that contour analysis and texture segregation are separable operations in shape processing. The patient's impairments are attributed to an inability to activate global processing of stimuli defined by texture but not by contours
A chronometric study of the posterior cerebellum's function in emotional processing
No full textThe posterior cerebellum is a recently discovered hub of the affective and social brain, with different subsectors contributing to different social functions. However, very little is known about when the posterior cerebellum plays a critical role in social processing. Due to its location and anatomy, it has been difficult to use traditional approaches to directly study the chronometry of the cerebellum. To address this gap in cerebellar knowledge, here we investigated the causal contribution of the posterior cerebellum to social processing using a chronometric transcranial magnetic stimulation (TMS) approach. We show that the posterior cerebellum is recruited at an early stage of emotional processing (starting from 100 ms after stimulus onset), simultaneously with the posterior superior temporal sulcus (pSTS), a key node of the social brain. Moreover, using a condition -and -perturb TMS approach, we found that the recruitment of the pSTS in emotional processing is dependent on cerebellar activation. Our results are the first to shed light on chronometric aspects of cerebellar function and its causal functional connectivity with other nodes of the social brain
Temporal segregation deficit in visual perception: a single case study
Full text linkThe patient (LD) presents a visual deficit in temporal segregation. PET scan showed a bilateral
hypometabolism in the superior parietal, temporal and occipital cortex. Neuropsychological data revealed
that memory, attention and language functions were almost completely preserved. Visual sensory tests
showed that visual acuity, depth and colour perception were normal, whereas detection of apparent motion
direction, flicker fusion and saccadic eye movements were abnormal. Shape drawing was impaired whereas
shape recognition (and naming), with either static or dynamic stimuli, was good. LD failed in tasks requiring
integration of elements to produce a whole image (line drawings, degraded and textured shapes). On the
other hand, LD’s performance was good in tasks not involving spatial integration, such as visual search and
letter-by-letter reading. The main finding is that LD failed in tasks requiring temporal segregation. These
tasks involved shape recognition when different shapes (Experiment 1a) or different parts of either a word or
a shape presented successively on the same retinal locus with (Experiments 2b, 3a, 3b) and without
(Experiments 4a, 4b) eye movements. Finally, LD has no problems in tasks (4c) involving temporal integration
alone. Taken together, these results suggest damage to a general mechanism involved in temporal
segregation
Progressive visual agnosia with posterior cortical atrophy
No full textA patient of posterior cortical atrophy, characterized by early signs of progressive visual agnosia is reported. Spect and MRI findings showed left unilateral parieto-occipital involvement in the earlier stage. Neurological and neuropsychological comments about progressive visual agnosia are reported
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
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