期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2005
卷号：102
期号：29
页码：10333-10338
DOI：10.1073/pnas.0500717102
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：For brain functions such as working memory and motor planning, neuronal circuits are able to sustain persistent activity after transient inputs. Theoretical studies have suggested that persistent activity can exist in recurrently connected networks as active reverberation. However, the actual cellular processes underlying such reverberation are not well understood. In this study, we investigated the basic synaptic mechanisms responsible for reverberatory activity in small networks of rat hippocampal neurons in vitro. We found that brief stimulation of one neuron in a network could evoke, in an all-or-none fashion, reverberatory activity lasting for seconds. The reverberation was likely to arise from recurrent excitation because it was eliminated by partial inhibition of {alpha}-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptors (but not by blockade of NMDA receptors). In contrast, blocking inhibitory transmission with bicuculline enhanced the reverberation. Furthermore, paired-pulse stimuli with interpulse intervals of 200-400 ms were more effective than single pulses in triggering reverberation, apparently by eliciting higher levels of asynchronous transmitter release. Suppressing asynchronous release by EGTA-AM abolished reverberation, whereas elevating asynchronous release by strontium substantially enhanced reverberation. Finally, manipulating calcium uptake into or release from intracellular stores also modulated the level of reverberation. Thus, the oft-overlooked asynchronous phase of synaptic transmission plays a central role in the emergent phenomenon of network reverberation.
