1,292 research outputs found

    Inducing Task-Relevant Responses to Speech in the Sleeping Brain

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    Falling asleep leads to a loss of sensory awareness and to the inability to interact with the environment [1]. While this was traditionally thought as a consequence of the brain shutting down to external inputs, it is now acknowledged that incoming stimuli can still be processed, at least to some extent, during sleep [2]. For instance, sleeping participants can create novel sensory associations between tones and odors [3] or reactivate existing semantic associations, as evidenced by event-related potentials [4; 5; 6 ; 7]. Yet, the extent to which the brain continues to process external stimuli remains largely unknown. In particular, it remains unclear whether sensory information can be processed in a flexible and task-dependent manner by the sleeping brain, all the way up to the preparation of relevant actions. Here, using semantic categorization and lexical decision tasks, we studied task-relevant responses triggered by spoken stimuli in the sleeping brain. Awake participants classified words as either animals or objects (experiment 1) or as either words or pseudowords (experiment 2) by pressing a button with their right or left hand, while transitioning toward sleep. The lateralized readiness potential (LRP), an electrophysiological index of response preparation, revealed that task-specific preparatory responses are preserved during sleep. These findings demonstrate that despite the absence of awareness and behavioral responsiveness, sleepers can still extract task-relevant information from external stimuli and covertly prepare for appropriate motor responses

    Bioassay-Guided Evaluation of Antinociceptive Effect of N-Salicyloyltryptamine: A Behavioral and Electrophysiological Approach

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    We investigated the antinociceptive and nerve excitability effects of the N-salicyloyltryptamine (NST) NST-treated mice exhibited a significant decrease in the number of writhes when 100 and 200 mg/kg (i.p.) were administered (i.p.). This effect was not antagonized by naloxone (1.5 mg/kg, i.p.). NST inhibited the licking response of the injected paw when 100 and 200 mg/kg were administered (i.p.) to mice in the first and second phases of the formalin test. Because the antinociceptive effects could be associated with neuronal excitability inhibition, we performed the single sucrose gap technique and showed that NST (3.57 mM) significantly reduced (29.2%) amplitude of the compound action potential (CAP) suggesting a sodium channel effect induced by NST. Our results demonstrated an antinociceptive activity of the NST that could be, at least in part, associated to the reduction of the action potential amplitude. NST might represent an important tool for pain management

    Sucesso adaptativo e percepções das perturbações hidrológicas por populações ribeirinhas em rios do semiárido brasileiro

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    Brazilian semi-arid streams are characterized by extreme hydrological events, with short periods of flooding and long periods of no surface water flow. Human populations living in the surroundings of these systems must be adapted to such hydrological disturbances. This paper evaluates the perceptions of riverine human populations in the Brazilian semi-arid, in relation to the hydrological disturbances, adaptations of such populations to withstand drought while maintaining social structure, and their utilization of the watershed during times of flooding. Data presented was collected from three riverine human populations that live near intermittent streams in the semi-arid region of Brazil. These populations rely mostly on the intermittent water supply from these systems and on the production from small-scaled agriculture and livestock. The surveyed populations maintain the stability of their social structures and organizations by producing an identification process through representations of hydrological disturbances (floods and drought). The resistance and resilience to these events basically involve strategies to avoid social ruptures, through the practice of subsistence agriculture, and the search for opportunities (e.g. adequate sites) to build weirs, wells and “cacimbas” (water holes). A simple yet well-structured scheme to utilize the watershed was found to be important during wet periods. The history of human adaptation to the Brazilian semi-arid depends on the configurations that both ecosystem and the social system take at each hydrological cycle. These aspects should be taken into account by decision-makers, and should be included in development-oriented policies adopted for the region. Any attempt to manage the semi-arid ecosystems should include the utilization of hydrological disturbances as part of the human element and its dimensions. Key words: riverine populations, survival strategies, flood, drought, stability, intermittent stream, semi-arid.Os rios do semiárido brasileiro são caracterizados por extremos hidrológicos, com curtos períodos de inundação e longos períodos de ausência de água. Populações humanas vivendo próximas a esses sistemas devem estar adaptadas a tais perturbações hidrológicas. Este trabalho avalia a percepção de populações ribeirinhas no semiárido brasileiro, considerando as perturbações hidrológicas, suas adaptações para resistir à seca enquanto mantêm a estrutura social e o uso da água durante os períodos de inundação. Este estudo foi realizado em três populações que vivem próximas a rios intermitentes na região semiárida do Brasil. Essas populações dependem principalmente da água de rios intermitentes para a agricultura em pequena escala e para a pecuária. As populações estudadas mantêm a estabilidade de suas estruturas e organizações sociais por meio das representações das perturbações hidrológicas (inundação e seca). A resistência e a resiliência a esses eventos envolvem basicamente estratégias para evitar rupturas sociais através da prática de agricultura de subsistência e pela procura de oportunidades (locais adequados) para construir açudes, poços e cacimbas. Um esquema simples e bem estruturado de utilização de água é também importante durante períodos de inundação. O histórico da adaptação humana no semiárido brasileiro resulta da conformação do ecossistema e do sistema social a cada ciclo hidrológico. Estes aspectos devem ser levados em conta por tomadores de decisões e devem ser considerados nas políticas que orientam o desenvolvimento dessa região. As ações de manejo nos ecossistemas do semiárido devem incluir a utilização das perturbações hidrológicas como parte do elemento humano e suas dimensões. Palavras-chave: populações ribeirinhas, estratégias de sobrevivência, inundação, seca, estabilidade, rio intermitente, semiárido

    Análise de longo prazo e obtenção do ano meteorológico típico para a usina fotovoltica flutuante de sobradinho

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    Para avaliar a geração de energia de centrais fotovoltaicas, é necessário analisar as variáveis ambientais associadas ao recurso solar na região de interesse durante vários anos. Neste trabalho, medições realizadas no Lago de Sobradinho de irradiância global inclinada, temperatura ambiente e velocidade do vento são utilizadas para corrigir séries de longo prazo dessas variáveis disponibilizadas por bases de dados históricas. Após obter as séries de longo prazo adaptadas ao local, um passo a passo é descrito e exemplificado para obtenção do ano meteorológico típico para a região de interesse. Em seguida, o ano meteorológico típico obtido é usado como entrada no software PVsyst previamente parametrizado de acordo com as características da Usina Fotovoltaica Flutuante (UFF) de Sobradinho para avaliar a geração de energia típica da usina. Os resultados mostram que a geração típica de energia da UFF - Sobradinho no ano inicial do projeto deve ser, em média, de 1797 MWh/ano.To assess the energy generation of photovoltaic plants, it is necessary to analyze the environmental variables associated with the solar resource in the region of interest for several years. In this work, measurements performed at Sobradinho's Lake of global irradiance on inclined plane, ambient temperature and wind speed are used to correct long-term series of these variables provided by historical databases. After obtaining the long-term series adapted to the location, a step by step is described and exemplified to obtain the typical meteorological year for the region of interest. Then, the typical meteorological year obtained is used as input in the PVsyst software previously parameterized according to the characteristics of the floating photovoltaic power (FPP) plant of Sobradinho to evaluate the typical power generation of the plant. The results show that the typical energy generation of Sobradinho FPP in the initial year of the project should be, on average, 1797 MWh/year.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

    Dopamine and serotonin in human substantia nigra track social context and value signals during economic exchange

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    Dopamine and serotonin are hypothesized to guide social behaviours. In humans, however, we have not yet been able to study neuromodulator dynamics as social interaction unfolds. Here, we obtained subsecond estimates of dopamine and serotonin from human substantia nigra pars reticulata during the ultimatum game. Participants, who were patients with Parkinson’s disease undergoing awake brain surgery, had to accept or reject monetary offers of varying fairness from human and computer players. They rejected more offers in the human than the computer condition, an effect of social context associated with higher overall levels of dopamine but not serotonin. Regardless of the social context, relative changes in dopamine tracked trial-by-trial changes in offer value—akin to reward prediction errors—whereas serotonin tracked the current offer value. These results show that dopamine and serotonin fluctuations in one of the basal ganglia’s main output structures reflect distinct social context and value signals
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