Sharp wave-associated high-frequency oscillation (200 Hz) in the intact hippocampus: network and intracellular mechanisms

作者：Aarne Ylinen, Anatol Bragin, Zoltán Nádasdy, Gábor Jandó, Imre Szabó, Attila Sı́k, György Buzsáki · 发表于：Journal of Neuroscience · 年份：1995 · DOI：10.1523/jneurosci.15-01-00030.1995 · 被引用次数：1117 · 研究领域：Photoreceptor and optogenetics research、Neural dynamics and brain function、Neuroscience and Neuropharmacology Research

Sharp wave bursts, induced by a cooperative discharge of CA3 pyramidal cells, are the most synchronous physiological pattern in the hippocampus. In conjunction with sharp wave bursts, CA1 pyramidal cells display a high-frequency (200 Hz) network oscillation (ripple). In the present study extracellular field and unit activity was recorded simultaneously from 16 closely spaces sites in the awake rat and the intracellular activity of CA1 pyramidal cells during the network oscillation was studied under anesthesia. Current source density analysis of the high-frequency oscillation revealed circumscribed sinks and sources in the vicinity of the pyramidal layer. Single pyramidal cells discharged at a low frequency but were phase locked to the negative peak of the locally derived field oscillation. Approximately 10% of the simultaneously recorded pyramidal cells fired during a given oscillatory event. Putative interneurons increased their discharge rates during the field ripples severalfold and often maintained a 200 Hz frequency during the oscillatory event. Under urethane and ketamine anesthesia the frequency of ripples was slower (100-120 Hz) than in the awake rat (180-200 Hz). Halothane anesthesia prevented the occurrence of high-frequency field oscillations in the CA1 region. Both the amplitude (1-4 mV) and phase of the intracellular ripple, but not its frequency, were voltage dependent. The amplitude of intracellular ripple was smallest between -70 and -80 mV. The phase of intra...