A key issue in cognitive neuroscience concerns the neural representation of conceptual knowledge. Currently, debate focuses around the issue of whether there are neural regions specialised for the processing of specific semantic attributes or categories, or whether concepts are represented in an undifferentiated neural system. Neuropsychological studies of patients with selective semantic deficits and previous neuroimaging studies do not unequivocally support either account. We carried out a PET study to determine whether there is any regional specialisation for the processing of concepts from different semantic categories using picture stimuli and a semantic categorisation task. We found robust activation of a large semantic network extending from left inferior frontal cortex into the inferior temporal lobe and including occipital cortex and the fusiform gyrus. The only category effect that we found was additional activation for animals in the right occipital cortex, which we interpret as being due to the extra visual processing demands required in order to differentiate one animal from another. We also carried out analyses in specific cortical regions that have been claimed to be preferentially activated for various categories, but found no evidence of any differential activation as a function of category. We interpret these data within the framework of cognitive accounts in which conceptual knowledge is represented within a nondifferentiated distributed system.

O objetivo foi investigar distúrbios do sono e fatores sociodemográficos e comportamentais associados. Foi realizado um censo com universitários. Perguntas extraídas do Munich Chronotype Questionnaire investigaram: duração insuficiente do sono (< 6 horas/dia para < 65 anos e < 5 horas/dia para os demais), latência longa (> 30 minutos), baixa qualidade autopercebida, despertares noturnos (involuntários, no meio da noite) e sonolência diurna (dificuldade de concentração). Variáveis independentes englobaram características sociodemográficas e comportamentais. Análises ajustadas foram feitas com regressão de Poisson. Dos 1.865 estudantes, 32% apresentaram sono insuficiente nos dias de aula, 8,2% sono insuficiente nos finais de semana, 18,6% latência longa nos dias de aula, 17,2% latência longa nos finais de semana, 30% baixa qualidade autopercebida, 12,7% despertares noturnos e 32,2% sonolência diurna. O maior consumo de álcool esteve associado à duração insuficiente e latência longa nos dias de aula, baixa qualidade, despertares e sonolência; tabagismo com duração insuficiente nos finais de semana, despertares e baixa qualidade; e cor da pele preta ou parda com duração insuficiente nos dias de aula, baixa qualidade e despertares. Ter aulas de manhã associou-se a sono insuficiente nos dias de aula e sonolência diurna, e o sexo feminino, sonolência, baixa qualidade e despertares. Os distúrbios de sono mais frequentes foram sono insuficiente nos dias de aula, baixa qualidade autopercebida e sonolência diurna. O consumo de álcool e cigarros e a cor preta ou parda foram os principais fatores associados aos distúrbios.

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Although audio-visual stimuli are among the most frequently used methods to elicit emotional reactions in experimental conditions, real-life manipulations have increasingly been used in different countries. However, the applicability of such protocols has not yet been tested in Brazilian Portuguese speakers. Thus, we conducted two experiments to investigate the effectiveness of both methods. In the first experiment, we used film clips to induce negative emotions (i.e., anger, fear, or sadness) or an emotionally neutral condition in 321 undergraduate students. After watching one of the online videos, volunteers completed an emotional assessment. As expected, there were significant differences in all groups. Our results corroborate the relatively discrete patterns in emotion elicitation using films. In the second experiment, anger was elicited in 18 male undergraduates through a hostile social interaction with a confederate and measured by the corrugator muscle activity and cortisol responses. Indeed, there was an increase in corrugator activity in the group exposed to anger induction, even after a few minutes from the end of the experimental manipulation. Implications for experiments on the negative emotions are discussed.

Social jetlag (SJL) is defined as the misalignment between the biological clocks and the social clock imposed by work and social constraints. In order to accomplish the workdays duties, people tend to not respect the internally sleep-wake cycle during the week, often using alarm clock to wake-up, which would lead to a chronic form of travel-induced jetlag. This circadian misalignment has been found to be associated with increased health risk and health-impairing behaviors. In this cross-sectional study, we aimed to explore whether the SJL is a valid concept for the travelinduced jetlag symptoms, as well as what is the cutoff point with best parameters for defining the presence of SJL, in a sample of undergraduate students of a university in Southern Brazil. We assessed SJL by the Munich ChronoType Questionnaire (MCTQ) and defined the concept as the difference between the midsleep point on free days and the midsleep point on classes days. The gold standard was defined as having at least one travel-induced jetlag symptom (fatigue, sleepiness or difficulty concentrating). Relative SJL, sensitivity and specificity were calculated for different cutoff points, plotted on ROC curves. A total of 452 students with complete sleep information were included in the analysis. The relative SJL mean was 2 h 23 min (SD = 1 h 24 min; range −3 h to 7 h 58 min) and 63.7% of the students had ≥2 h of relative SJL. All the tested cutoff points of the instrument had low sensitivity and specificity values, covering a small area under the ROC curve (0.487). The best parameters were for the cutoff point ≥2 h, with 63.4% sensitivity and 35.9% specificity. SJL did not revealed to be a valid concept for the studied sample comparing it to travel-induced jetlag symptomatology. One possible explanation for the lack of validity of our results regards the fact that SJL may not have the same apparent wide-term effects as the travel-induced jetlag. Then, the symptoms of SJL do not well represent the symptoms of travel-induced jetlag.

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