Top-down modulation of brain activity underlying intentional action and its relationship with awareness of intention: an ERP/Laplacian analysis

Item does not contain fulltextIntentional actions are executed with the peculiar experience of "I decide to do that." It has been proposed that intentional actions involve a specific brain network involving the supplementary motor areas (SMAs). Here, we manipulated the internal representation participants attended to (intention vs. movement) in order to (1) examine the activity of SMAs and of the primary motor cortex (M1) during intentional action preparation and execution, and (2) investigate the temporal relationship between activity in these structures and intention awareness. Participants performed self-paced key presses. After each key press, participants were asked to report either the time they had the first intention to press the key (W-condition) or the time they actually started the movement (M-condition). We then estimated surface Laplacians from brain electrical potentials recorded while participants were performing the task. Activity in SMAs was greater in the W-condition than in the M-condition more than 1 s before electromyographic (EMG) activation, suggesting that this region is indeed associated to the formation of conscious intention. Conversely, activity in primary motor cortex (M1) contralateral to the responding hand was larger in the M-condition than in the W-condition, revealing that this region is also modulated by top-down processes. In addition, waveforms time-locked to the W-judgement revealed that M1 as well as EMG activation preceded the time at which participants become aware of their intention by about 0.3 s. This observation argues against the possibility that the temporal delay between motor-related activation and intention awareness results from smearing artifacts.11 p

Sistema de informações sobre nascidos vivos: um estudo de revisão Brazilian live birth information system: a review study

O objetivo deste estudo foi realizar uma revisão de literatura sobre o uso do Sistema de Informações sobre Nascidos Vivos (SINASC) na pesquisa em saúde. As bases de dados MEDLINE, LILACS e SciELO foram pesquisadas no período de 1994 a 2005, utilizando-se a combinação dos seguintes descritores: "SINASC", "live birth", "Brazil". Foram identificados 157 resumos dentro do período de referência, dos quais 44 foram selecionados e classificados segundo critérios específicos. O número de artigos publicados por ano cresceu ao longo do período estudado. A maioria dos estudos foi desenvolvida na região Sudeste e empregou o município como a unidade geográfica da análise. Uma gama variada de temas foi avaliada, incluindo descrições do perfil de nascidos vivos, avaliações de serviços e programas de saúde e fatores de risco para desfechos infantis. Concluindo, embora o SINASC represente uma fonte de dados importante para a pesquisa sobre a saúde materno-infantil, a cobertura do sistema e a confiabilidade dos seus dados precisam ser melhor avaliadas.<br>The aim of this study was to perform a systematic review of the use of the Live Birth Information System (Sistema de Informações de Nascidos Vivos SINASC) in health research. MEDLINE, LILACS and SciELO databases were searched from 1994 to 2005 using the following combination of descriptors: "SINASC", "live birth", "Brazil". We identified 157 abstracts within the reference period, among which 44 were selected and classified according to specific criteria. The number of articles published per year increased during the period studied. The majority of the studies was carried out in the Southeast region and used the municipality as the geographic unity of analysis. A varied range of subjects were assessed including descriptions of live births profiles, health service and programs evaluations and risk factors for infant outcomes. In conclusion, although the SINASC represents an important data source for maternal-infant health research, the system's coverage and the reliability of its data need to be better evaluated