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Sharp wave–ripple complexes (SPW-R) are oscillatory patterns in the mammalian brain hippocampus during immobility and slow wave sleep. There are three major network oscillation patterns in the hippocampus: theta, SPW-R and gamma. Gamma oscillations are found in all major brain structures, whereas theta and sharp waves are specific to the hippocampus and its neighbouring areas. SPW-Rs are composed of large amplitude sharp waves in local field potential and associated fast field oscillations as known as ripples. SPW-Rs are shown to be involved in memory consolidation and the replay of wakefulness-acquired memory. These network oscillations are the most synchronous patterns in the brain, making them susceptible to pathological patterns such as epilepsy. ==History and background== Neuronal oscillations are important components of neuroscience research. During the last two decades, hippocampal oscillations have been a major focus in the research of neuronal oscillations. Among different oscillations present in the brain, SPW-Rs are the first and only population activity that start in the developing hippocampus, but they are the least understood network pattern of the hippocampus. Originally, these large waves were observed by Cornelius Vanderwolf in 1969, and later John O'Keefe investigated SPW-Rs in more detail in 1978 while studying the spatial memory of rats.〔 Györgyi Buzsáki and his collaborators studied and characterized SPW-Rs in detail and described their physiological functions and role in different states of the animal.〔〔 These patterns are large amplitude, aperiodic recurrent oscillations occurring in the apical dendritic layer of the CA1 regions of the hippocampus. Sharp waves are followed by a synchronous fast field oscillation (140–200 Hz frequency), named ripples. Features of these oscillations provided evidences for their role in inducing synaptic plasticity and memory consolidation. Among these features are their widespread effect on the population neurons in the hippocampus, and the experience-dependent content of participating neurons. Studies have shown that elimination of SPW-Rs by electrical stimulation interfered with rats ability to recall the spatial memory information. These features support functional role of sharp-wave ripple complexes in memory consolidation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sharp wave–ripple complexes」の詳細全文を読む スポンサード リンク
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