América Latina: política y religión

América Latina es actualmente una de las regiones más interesantes para las investigaciones del fenómeno de la religión, sus transformaciones contemporáneas y las relaciones dialécticas entre la religión y el mundo de la política. Estas dimensiones se entremezclan desde los tiempos coloniales, pero es ahora cuando se puede observar que la fuerza de la religión, en el contexto social y político del continente latinoamericano, está creciendo bruscamente. Aparecen nuevas iglesias y movimientos religiosos comprometidos políticamente, y la afiliación religiosa empieza a influir cada vez más, a la hora de las elecciones, en las decisiones de los latinoamericanos

Structural reorganization of the early visual cortex following Braille training in sighted adults

Training can induce cross-modal plasticity in the human cortex. A well-known example of this phenomenon is the recruitment of visual areas for tactile and auditory processing. It remains unclear to what extent such plasticity is associated with changes in anatomy. Here we enrolled 29 sighted adults into a nine-month tactile Braille-reading training, and used voxel-based morphometry and diffusion tensor imaging to describe the resulting anatomical changes. In addition, we collected resting-state fMRI data to relate these changes to functional connectivity between visual and somatosensory-motor cortices. Following Braille-training, we observed substantial grey and white matter reorganization in the anterior part of early visual cortex (peripheral visual field). Moreover, relative to its posterior, foveal part, the peripheral representation of early visual cortex had stronger functional connections to somatosensory and motor cortices even before the onset of training. Previous studies show that the early visual cortex can be functionally recruited for tactile discrimination, including recognition of Braille characters. Our results demonstrate that reorganization in this region induced by tactile training can also be anatomical. This change most likely reflects a strengthening of existing connectivity between the peripheral visual cortex and somatosensory cortices, which suggests a putative mechanism for cross-modal recruitment of visual areas

Mental rotation task in bipolar disorder

Aim. Bipolar disorder (BD) significantly affects level of cognitive and motor functioning. Studies on cognitive function in BD shows i.a. deficits in visuospatial processing and visuospatial memory. However, studies have not used Mental Rotation Task to evaluate these functions so far. Our aim is to introduce this method to assess abovementioned deficits in euthymic BD patients. Method. 31 euthymic BD patients and 27 healthy volunteers matched for age and years of education were recruited. All participants performed digital version of Mental Rotation Task. In this task, participants were asked to compare two figures rotated against each other and declare its similarity or difference indicating whether the figures are identical or whether they constitute their own mirror image.. Results. The test revealed significantly longer reaction times in the group of BD patients when images were rotated by – 90, – 45, 45, 90 degrees, or not rotated at all. There was no significant difference in condition of – 135, 135 or 180 degrees. The accuracy rate was significantly lower in the patient group than in the control group for the entire test and in each condition. The correlation between the average response time and the accuracy rate turned out to be insignificant. Conclusions. Our results are consistent with studies presenting visuospatial deficits in bipolar disorder. In this study we show for the first time that mental rotation deficits are present in euthymic state of BD patients

Relationship between neurological and cerebellar soft signs, and implicit motor learning in schizophrenia and bipolar disorder

Background: Schizophrenia (SZ) and bipolar disorder (BD) patients share deficits in motor functions in the form of neurological (NSS) and cerebellar soft signs (CSS), and implicit motor learning disturbances. Here, we use cluster analysis method to assess (1) the relationship between those abnormalities in SZ and BD and (2) the differences between those groups. Methods: 33 SZ patients, 33 BD patients as well as 31 healthy controls (HC) took part in the study. We assessed CSS with the International Cooperative Ataxia Rating Scale (ICARS) and NSS with the Neurological Evaluation Scale (NES). Implicit motor learning was evaluated with the Serial Reaction Time Task (SRTT). Participants were divided into clusters (Ward's method) based on the mean response time and mean error rate in SRTT. The difference in ICARS and NES scores, and SRTT variables between clusters were evaluated. We have measured associations between SRTT parameters and both ICARS and NES total scores and subscores. Results: Cluster analysis based on the SRTT parameters allowed to extract three clusters. Those were characterized by the increasing disruption of motor functioning (psychomotor retardation, the severity of NSS and CSS) regardless of the diagnosis. Cluster 1 covered almost all of HC and was characterized by faster reaction times and small number of errors. BD and SZ patients represented in cluster 1, although fully functional in performing the SRTT, showed higher rates of NSS and CSS. Patients with BD and SZ were set apart in clusters 2 and 3 in a similar proportion. Cluster 2 presented significantly slower reaction times but with the comparable number of errors to cluster 1. Cluster 3 consisted of participants with normal or decreased reaction time and significantly increased number of errors. None of the clusters were predominantly composed of the patients representing one psychiatric diagnosis. Conclusions: To our best knowledge, we are presenting the first data indicating the relationship between implicit motor learning and NSS and CSS in SZ and BD patients' groups. Lack of clusters predominantly represented by patients with the diagnosis of SZ or BD may refer to the model of schizophrenia-bipolar disorder boundary, pointing out the similarities between those two disorders

La modularité du traitement de haut-niveau des couleurs : l’apport de la neuropsychologie

We examined the effects of brain lesions in humans on the interdependences between three modules of cortical colour processing, namely colour perception, naming and object-colour knowledge. We first focused on colour categorisation - a case-in-point of the interplay between perception and language. Reviewed evidence from cognitive development, comparative psychology and cognitive neuroscience hints that colour categorisation originates from neither perception nor language, as assumed by the Nature-Nurture debate. Instead, colour categories may reflect relevant objects in the environment. To assess the causal link between categorization and naming, we investigated a stroke patient, RDS. Despite severe difficulties in naming chromatic colours, due to a left occipito-temporal lesion, RDS’s colour categorisation was relatively spared. Multimodal MRI experiments revealed that the language-perception connectivity is essential for efficient colour naming but not for categorisation. Investigation of object-colour knowledge in the context of RDS’s colour-naming impairment showed that RDS could not link colour perception to neither language nor semantic knowledge. He could not associate a visual colour to a colour name or to the shape of its typical object. Overall, we demonstrated three functional segregations in colour processing: between (1) colour categorisation and colour naming, (2) naming of chromatic and achromatic colours and (3) knowing about coloured objects and knowing about abstract colours. The main purpose of high-level cortical colour mechanisms could be providing sensory and semantic information to guide object-related behaviour, by achieving (1) stable colour perception, (2) relevant colour categories, and (3) joint mental representations of shapes and colours. These neural computations may have been recycled in cultural evolution to isolate colours from objects and label them with names.Nous avons examiné comment des lésions cérébrales chez l'homme affectent les interdépendances entre trois modules de traitement cortical de la couleur, notamment : la perception, la dénomination et la connaissance de la couleur de l'objet. Nous avons étudié la catégorisation des couleurs - un exemple de l'interaction entre la perception et le langage. Les preuves provenant du développement cognitif, de la psychologie comparée et des neurosciences cognitives suggèrent que la catégorisation des couleurs ne provient ni de la perception ni du langage, comme le présume le débat Nature-Nurture. Les catégories de couleurs peuvent plutôt refléter des objets pertinents dans l'environnement. Pour évaluer la causalité entre la catégorisation et la dénomination, nous avons étudié un patient victime d'un AVC, le RDS. Malgré de difficultés pour nommer les couleurs chromatiques, résultant d’une lésion occipito-temporale gauche, la catégorisation des couleurs était relativement épargnée chez RDS. Des expériences d'IRM multimodale ont révélé que la connectivité perception-langage est essentielle pour un nommage efficace des couleurs, mais pas pour une catégorisation. L’étude de la connaissance de la couleur des objets dans le contexte de la dégradation des noms de couleurs de RDS a montré que celui-ci ne pouvait pas lier la perception des couleurs au langage ni à la connaissance sémantique. Il ne pouvait pas associer une couleur visuelle à un nom de couleur ou à la forme de son objet typique. Globalement, nous avons démontré trois ségrégations fonctionnelles dans le traitement cortical des couleurs, entre : (1) la catégorisation et la dénomination des couleurs, (2) la dénomination des couleurs chromatiques et achromatiques et (3) la connaissance des objets colorés et celle des couleurs abstraites. Les mécanismes corticaux du traitement des couleurs pourraient avoir pour objectif de lier des informations sensorielles et sémantiques afin de guider le comportement lié aux objets, en réalisant (1) une perception des couleurs stable, (2) des catégories de couleurs pertinentes et (3) des représentations mentales communes des formes et des couleurs. L'évolution culturelle peut avoir recyclé les circuits neuronaux nécessaires à ces processus pour isoler la couleur de l'objet et l'étiqueter avec des noms de couleur

The biological bases of colour categorisation: from goldfish to the human brain

How are colour categories related to perception and language? To answer this question, we review research on the neural correlates of colour categories, and categorical responses in preverbal infants and non-human animals. With respect to language, the reviewed findings suggest that colour categorisation often involves automatic language processing. At the same time, evidence from non-human animals, infants, and patients with brain lesions indicates that colour categorisation may also occur in the absence of language. Concerning perception, there is little convincing evidence that the bottom-up processes of colour perception are the origin of colour categories. Instead, colour categorisation might simply build upon the continuous colour perception and interact with perception through the direction of attention to colour differences that are relevant to categorisation. We make three suggestions for future research. First, future research in all areas requires methodological improvements, in particular in stimulus control. Second, future research should overcome the universalist-realist debate and go beyond a simple contrast between perception and language. Third, the link between object colours and colour categories provides an alternative approach that might reveal the ecological origin of colour categories. The ecological approach promises establishing evolutionary and developmental continuity between categorical responses in non-human animals, infants and adult humans

Color naming and categorization depend on distinct functional brain networks

Naming a color can be understood as an act of categorization, that is, identifying it as a member of a category of colors that are referred to by the same name. But are naming and categorization equivalent cognitive processes and consequently rely on same neural substrates? Here, we used task and resting-state functional magnetic resonance imaging as well as behavioral measures to identify functional brain networks that modulated naming and categorization of colors. We first identified three bilateral color-sensitive regions in the ventro-occipital cortex. We then showed that, across participants, color naming and categorization response times (RTs) were correlated with different resting state connectivity networks seeded from the color-sensitive regions. Color naming RTs correlated with the connectivity between the left posterior color region, the left middle temporal gyrus, and the left angular gyrus. In contrast, color categorization RTs correlated with the connectivity between the bilateral posterior color regions, and left frontal, right temporal and bilateral parietal areas. The networks supporting naming and categorization had a minimal overlap, indicating that the 2 processes rely on different neural mechanisms

When colours split from objects: The disconnection of colour perception from colour language and colour knowledge

We investigated object-colour knowledge in RDS, a patient with impaired colour naming after a left occipito-temporal stroke. RDS’s colour perception, object naming and verbal colour-knowledge (the ability to verbally say the typical colour of an object) were relatively spared. RDS was also able to state if an object was appropriately coloured or not. However, he could neither match colour names to coloured objects, nor match colour patches to grey-scale objects. Thus, RDS’s colour-naming deficit was associated with an impaired ability to conceptually relate visually presented object shapes and colours. These results suggest that objects in their typical colour are processed holistically in the visual modality, and that abilities important for colour naming may also be involved in abstracting colours from visual objects. We discuss these findings in the context of developmental psychology and linguistic anthropology, and propose a model of neuro-functional organization of object-colour knowledge

Braille in the Sighted: Teaching Tactile Reading to Sighted Adults

International audienceBlind people are known to have superior perceptual abilities in their remaining senses. Several studies suggest that these enhancements are dependent on the specific experience of blind individuals, who use those remaining senses more than sighted subjects. In line with this view, sighted subjects, when trained, are able to significantly progress in relatively simple tactile tasks. However, the case of complex tactile tasks is less obvious, as some studies suggest that visual deprivation itself could confer large advantages in learning them. It remains unclear to what extent those complex skills, such as braille reading, can be learnt by sighted subjects. Here we enrolled twenty-nine sighted adults, mostly braille teachers and educators, in a 9-month braille reading course. At the beginning of the course, all subjects were naive in tactile braille reading. After the course, almost all were able to read whole braille words at a mean speed of 6 words-per-minute. Subjects with low tactile acuity did not differ significantly in braille reading speed from the rest of the group, indicating that low tactile acuity is not a limiting factor for learning braille, at least at this early stage of learning. Our study shows that most sighted adults can learn whole-word braille reading, given the right method and a considerable amount of motivation. The adult sensorimotor system can thus adapt, to some level, to very complex tactile tasks without visual deprivation. The pace of learning in our group was comparable to congenitally and early blind children learning braille in primary school, which suggests that the blind's mastery of complex tactile tasks can, to a large extent, be explained by experience-dependent mechanisms