A Novel Visualization Method for Sleep Spindles Based on Source Localization of High Density EEG

Equivalent dipole source localization is a well-established approach to localizing the electrical activity in electroencephalogram (EEG). So far, source localization has been used primarily in localizing the epileptic source in human epileptic patients. Currently, source localization techniques have been applied to account for localizing epileptic source among the epileptic patients. Here, we present the first application of source localization in the field of sleep spindle in mouse brain. The spatial distribution of cortical potential was obtained by high density EEG and then the anterior and posterior sleep spindles were classified based on the K-mean clustering algorithm. To solve the forward problem, a realistic geometry brain model was produced based on boundary element method (BEM) using mouse MRI. Then, we applied four different source estimation algorithms (minimum norm, eLORETA, sLORETA, and LORETA) to estimate the spatial location of equivalent dipole source of sleep spindles. The estimated sources of anterior and posterior spindles were plotted in a cine-mode that revealed different topographic patterns of spindle propagation. The characterization of sleep spindles may be better be distinguished by our novel visualization method.

Sleep spindles: validated concepts and breakthroughs: [review]

INTRODUCTION: Sleep spindles, the hallmark of sleep synchronization in stage 2 non-REM sleep, are rhythmic and monomorphic waves, between 10 and 14 Hz, with a maximum amplitude in the vertex (Cz), with bilateral irradiation to central regions (C3 and C4). OBJECTIVE: In this article we present an overview of sleep spindles ranging from well established concepts of morphology, generation mechanisms, maturational features, abnormal patterns and pathological aspects since the knowledge is important to identify the normal and abnormal patterns. CONCLUSION: Centro-parietal and frontal spindle are normal pattern and extreme spindle is abnormal, mostly found in children mentally retarded up to 5 years-old. In this review research boundaries of memory consolidation, synaptic potentiation and brain plasticity were also presented.

INTRODUÇÃO: Fusos de sono, marco da sincronização do sono no estágio 2 do sono não-REM, são ondas rítmicas e monomórficas, entre 10 e 14 Hz, com amplitude máxima no vértex (Cz), e irradiação bilateral para áreas centrais (C3 e C4). OBJETIVO: Neste artigo apresentamos uma revisão sobre fusos de sono abrangendo conceitos bem estabelecidos de morfologia, mecanismos de geração, características maturacionais, padrões anormais e aspectos patológicos, uma vez que o conhecimento se faz necessário para a identificação de padrões normais e patológicos. CONCLUSÕES: Fusos centro-parietal e frontal são padrões fisiológiocs normais do sono fase 2 enquanto fusos extremos é um padrão patológico encontrado em crianças abaixo de 5 anos com retardo mental. Fronteiras da pesquisas quanto à consolidação da memória, potenciação sináptica e plasticidade cerebral também foram revisados.