The hierarchical organization of semantic memory: executive function in the processing of superordinate concepts.

Research on the processing of objects at different hierarchical levels has suggested that understanding superordinate concepts (e.g. fruit), relative to basic level concepts (e.g. apple), requires greater semantic control demands. Yet, it is unclear which factors underlie this difference in executive processing. We built on previous research showing that superordinate concepts have less shared features among their members and therefore may involve higher semantic control requirements. To test this hypothesis, we developed an fMRI study in which we orthogonally manipulated feature sharedness (more shared vs. less shared) and concept level (superordinate vs. basic) in a sentence verification task. Sentences involving less shared features, relative to more shared features, significantly engaged the L lateral PFC. Importantly, sentences that included superordinate concepts, relative to those with basic level concepts, also revealed a stronger response in L lateral PFC, along with posterior temporal gyrus activation. There was also a significant interaction between feature sharedness and concept level in several PFC regions and L posterior temporal areas. The results suggest that relative to basic level concepts, processing superordinate concepts requires extra semantic control in L lateral PFC to coordinate information that is less shared by other members of the category level. These findings demonstrate that feature sharedness impacts the neural basis of semantic knowledge, and is a critical dimension in the processing of superordinate concepts.

Sensitivity and salience of form-function correlations of objects: evidence from feature tasks.

The present research evaluates the sensitivity and salience of form-function correlations in contrast with other types of feature correlations (function-function, form-form) in adults and using real object features (from tools and utensils). In Experiment 1, the participants judged the relation between the form and function features of tools. In Experiment 2, participants were asked to generate a second feature related to a given form or function feature. In Experiment 3, participants were asked to make a lexical decision in which form and function features were used as primes and targets. The results showed that even though participants were sensitive to form-function correlations, these were not particularly salient when compared with other feature-type correlations, notably function-function correlations. Our data underline the overall importance of function information to object representations and the impact of the statistical co-occurrence of features when processing object features.

Disulfiram-induced epileptic seizures.

Disulfiram has been widely used for over six decades in the treatment of alcohol dependence, as an aversive therapeutic agent. Despite having very few side effects when taken without concurrent alcohol consumption, some of these may underlie serious clinical complications. Epileptic seizure induction is a rare adverse effect of disulfiram and its aetiological mechanism is unknown. We present a hospitalised 47-year-old male patient with two episodes of generalised tonic-clonic seizures during treatment with disulfiram while abstinent from alcohol.

Visual phenotype in Williams-Beuren syndrome challenges magnocellular theories explaining human neurodevelopmental visual cortical disorders.

Williams-Beuren syndrome (WBS), a neurodevelopmental genetic disorder whose manifestations include visuospatial impairment, provides a unique model to link genetically determined loss of neural cell populations at different levels of the nervous system with neural circuits and visual behavior. Given that several of the genes deleted in WBS are also involved in eye development and the differentiation of retinal layers, we examined the retinal phenotype in WBS patients and its functional relation to global motion perception. We discovered a low-level visual phenotype characterized by decreased retinal thickness, abnormal optic disk concavity, and impaired visual responses in WBS patients compared with age-matched controls by using electrophysiology, confocal and coherence in vivo imaging with cellular resolution, and psychophysics. These mechanisms of impairment are related to the magnocellular pathway, which is involved in the detection of temporal changes in the visual scene. Low-level magnocellular performance did not predict high-level deficits in the integration of motion and 3D information at higher levels, thereby demonstrating independent mechanisms of dysfunction in WBS that will require remediation strategies different from those used in other visuospatial disorders. These findings challenge neurodevelopmental theories that explain cortical deficits based on low-level magnocellular impairment, such as regarding dyslexia.

Motion integration deficits are independent of magnocellular impairment in Parkinson's disease.

Motion processing involves multiple hierarchical steps, from the magnocellular pathway, sensitive to high temporal frequency modulations, to subsequent motion integration within the visual cortical dorsal stream. We have tested whether motion integration deficits in mild Parkinson disease (PD) can be explained by visual deficits in earlier processing nodes. Contrast sensitivity deficits in the magnocellular pathway, were compared with speed discrimination of local dots moving in random directions, speed and direction discrimination of moving surfaces and motion integration as measured by 2D coherence thresholds (n=27). We have found that low-level magnocellular impairment in PD does not explain deficits in subsequent steps in motion processing. High-level performance was abnormal in particular for tasks requiring perception of coherently moving surfaces. Motion coherence deficits were predictive of visuomotor impairment, corroborating a previous magnetic stimulation study in normal subjects. We conclude that dorsal stream deficits in PD have a high-level visual cortical basis independent of low-level magnocellular damage.

Specific retinotopically based magnocellular impairment in a patient with medial visual dorsal stream damage.

We report here retinotopically based magnocellular deficits in a patient with a unilateral parieto-occipital lesion. We applied convergent methodologies to study his dorsal stream processing, using psychophysics as well as structural and functional imaging. Using standard perimetry we found deficits involving the periphery of the left inferior quadrant abutting the horizontal meridian, suggesting damage of dorsal retinotopic representations beyond V1. Retinotopic damage was much more extensive when probed with frequency-doubling based contrast sensitivity measurements, which isolate processing within the magnocellular pathway: sensitivity losses now encroached on the visual central representation and did not respect the horizontal meridian, suggesting further damage to dorsal stream retinotopic areas that contain full hemi-field representations, such as human V3A or V6. Functional imaging revealed normal responses of human MT+ to motion contrast. Taken together, these findings are consistent with a recent proposal of two distinct magnocellular dorsal stream pathways: a latero-dorsal pathway passing to MT+ and concerned with the processing of coherent motion, and a medio-dorsal pathway that routes information from V3A to the human homologue of V6. Anatomical evidence was consistent with sparing of the latero-dorsal pathway in our patient, and was corroborated by his normal performance in speed, direction discrimination and motion coherence tasks with 2D and 3D objects. His pattern of dysfunction suggests damage only to the medio-dorsal pathway, an inference that is consistent with structural imaging data, which revealed a lesion encompassing the right parieto-occipital sulcus.

Visual magnocellular and structure from motion perceptual deficits in a neurodevelopmental model of dorsal stream function.

Williams syndrome (WS) is a neurodevelopmental disorder of genetic origin that has been used as a model to understand visual cognition. We have investigated early deficits in the afferent magnocellular pathway and their relation to abnormal visual dorsal processing in WS. A spatiotemporal contrast sensitivity task that is known to selectively activate that pathway was used in six WS subjects. Additionally, we have compared visual performance in 2D and 3D motion integration tasks. A novel 3D motion coherence task (using spheres with unpredictable axis of rotation) was used in order to investigate possible impairment of occipitoparietal areas that are known to be involved in 3D structure from motion (SFM) perception. We have found a significant involvement of low-level magnocellular maps in WS as assessed by the contrast sensitivity task. On the contrary, no significant differences were observed between WS and the control groups in the 2D motion integration tasks. However, all WS subjects were significantly impaired in the 3D SFM task. Our findings suggest that magnocellular damage may occur in addition to dorsal stream deficits in these patients. They are also consistent with recently described genetic and neuroanatomic abnormalities in retinotopic visual areas. Finally, selective SFM coherence deficits support the proposal that there is a specific pathway in the dorsal stream that is involved in motion processing of 3D surfaces, which seems to be impaired in this disorder.

Fatores de risco para a saúde mental infanto-juvenil: conhecimentos dos agentes educativos / Factores de riesgo para la salud mental infanto-juvenil: conocimientos de los agentes educativos / Risk factors for mental health in children and young people: knowledge of education agents

Resumo Objetivo Avaliar o nível de conhecimentos dos agentes educativos sobre os fatores de risco para a saúde mental de crianças e adolescentes e analisar a sua associação com variáveis sociodemográficas. Métodos Estudo quantitativo, com recurso a uma amostra não probabilística de 136 agentes educativos (62,5% professores, 32,4% enfermeiros e 5,1% polícias), na sua maioria mulheres (70,6%) e média de idades de 48,34 anos. A colheita de dados, com recurso a um questionário de auto-preenchimento, realizou-se no ano lectivo de 2018 em quatro escolas do concelho de Viseu - Região centro de Portugal. Testes estatísticos utilizados: Qui-Quadrado e Análise de Regressão Múltipla. Resultados Na generalidade os agentes educativos revelaram possuir conhecimentos sobre os fatores de risco para a saúde mental, destacando-se 39,71% que chegam mesmo a evidenciar excelentes conhecimentos. Em termos comparativos, os enfermeiros são os que evidenciam melhores níveis de conhecimentos ( x̄ =15,546), seguindo-se os professores ( x̄ =13,318) e, por fim, os polícias ( x̄ =8,571), diferenças estas significativas (x2=14,725; p= 0,004). O estudo multivariado inferiu ser o género a única variável a se revelar preditora do nível de conhecimentos, explicando 11,5% da sua variabilidade (p=0,002), evidenciando as mulheres maior nível de conhecimentos. Já o efeito preditivo da variável categoria profissional (p=0,051) e tempo de experiência profissional (p=0,0179) não se revelou significativo. Conclusão O facto do género ter sido a única variável que se revelou preditiva do nível de conhecimentos, faz-nos ponderar da necessidade de se adoptarem estratégias diferenciadas em programas de formação, onde as características e vulnerabilidade dos dois sexos sejam salvaguardadas.

Resumen Objetivo Evaluar el nivel de conocimiento de los agentes educativos sobre los factores de riesgo para la salud mental de niños y adolescentes y analizar su relación con variables sociodemográficas. Métodos Estudio cuantitativo, con un muestreo no probabilístico de 136 agentes educativos (62,5% profesores, 32,4% enfermeros y 5,1% policías), en su mayoría mujeres (70,6%) y con un promedio de edad de 48,34 años. La recolección de datos se realizó mediante un cuestionario autocompletado, en el año lectivo 2018, en cuatro escuelas del concejo de Viseu, en la región centro de Portugal. Las pruebas estadísticas utilizadas fueron: prueba χ2 de Pearson y Análisis de Regresión Múltiple. Resultados En general, los agentes educativos revelaron tener conocimientos sobre los factores de riesgo para la salud mental, con un 39,71% que logró demostrar excelentes conocimientos. En términos comparativos, los enfermeros son los que demuestran mejores niveles de conocimiento ( x̄ =15,546), seguidos de los profesores ( x̄ =13,318) y por último los policías ( x̄ =8,571), diferencias estas significativas (x2=14,725; p= 0,004). Con el estudio multivariado se reveló que el género es la única variable que se mostró predictiva del nivel de conocimiento, que explica el 11,5% de su variabilidad (p=0,002) y demuestra mayor nivel de conocimiento en mujeres. Por otro lado, el efecto predictivo de la variable categoría profesional (p=0,051) y tiempo de experiencia profesional (p=0,0179) no demostró ser significativo. Conclusión El hecho de que el género haya sido la única variable que demostró ser predictiva del nivel de conocimiento nos hace considerar la necesidad de adoptar estrategias diferenciadas en programas de capacitación, en los que las características y vulnerabilidad de los dos sexos sean resguardadas.

Abstract Objective To assess the level of knowledge of education agents about risk factors for mental health in children and adolescents, and to analyze these factors connection with sociodemographic variables. Methods This was a quantitative study that used non-probabilistic sample of 136 education agents (62.5% professors, 32.4% nurses and 5.1% police officers). Most of participants were women (70.6%) with mean age of 48.34 years old. Data collection was performed through a self-completion questionnaire during 2018 academic year in four schools of the municipality of Viseu, Central Portugal. Statistical tests used were chi-square and multiple regression analysis. Results In general, education agents showed to have knowledge about risk factors for mental health, highlighting that 39.71% of them had excellent knowledge. In comparative terms, nurses showed better level of knowledge ( x̄ =15.546), followed by professors ( x̄ =13.318) and, police officers ( x̄ =8.571). Differences between participants were significant (x2=14.725; p= 0.004). The multivariate study demonstrated that gender was the only variable to prove to be a predictor of the level of knowledge, explaining the 11.5% of variability (p=0.002), and showing that women had a greater level of knowledge. The predictive effect of the variable professional category (p=0.051) and years of professional experience (p=0.0179) was not significant. Conclusion The fact that gender was the only variable that proved to be predictive of the level of knowledge led us consider the need of adopting differentiated strategies for training programs, in which the characteristics and vulnerability of both sexes should be protected.