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This Article Full Text Full Text (PDF) All Versions of this Article: 576/2/457    most recent jphysiol.2006.114918v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wu, C. P. Articles by Zhang, L. Search for Related Content PubMed PubMed Citation Articles by Wu, C. P. Articles by Zhang, L. Related Collections Neuroscience

¹ Toronto Western Research InstituteUniversity Health Network
² Department of Medicine, (Division of Neurology)
³ Department of Physiology
⁴ Institute of Biomaterials and Biomedical Engineering
⁵ Epilepsy Research Program
⁶ Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada M5T 2S8

The rodent hippocampal circuit is capable of exhibiting in vitro spontaneous rhythmic field potentials (SRFPs) of 1–4 Hz that originate from the CA3 area and spread to the CA1 area. These SRFPs are largely correlated with GABA-A IPSPs in pyramidal neurons and repetitive discharges in inhibitory interneurons. As such, their generation is thought to result from cooperative network activities involving both pyramidal neurons and GABAergic interneurons. Considering that the hippocampus, subiculum and entorhinal cortex function as an integrated system crucial for memory and cognition, it is of interest to know whether similar SRFPs occur in hippocampal output structures (that is, the subiculum and entorhinal cortex), and if so, to understand the cellular basis of these subicular and entorhinal SRFPs as well as their temporal relation to hippocampal SRFPs. We explored these issues in the present study using thick hippocampal–subicular–entorhinal cortical slices prepared from adult mice. SRFPs were found to spread from the CA1 area to the subicular and entorhinal cortical areas. Subicular and entorhinal cortical SRFPs were correlated with mixed IPSPs/EPSPs in local pyramidal neurons, and their generation was dependent upon the activities of GABA-A and AMPA glutamate receptors. In addition, the isolated subicular circuit could elicit SRFPs independent of CA3 inputs. We hypothesize that the SRFPs represent a basal oscillatory activity of the hippocampal–subicular–entorhinal cortices and that the subiculum functions as both a relay and an amplifier, spreading the SRFPs from the hippocampus to the entorhinal cortex.

(Received 7 June 2006; accepted after revision 28 July 2006; first published online 3 August 2006)
Corresponding author L. Zhang: Room 13-411, Toronto Western Hospital, 399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8. Email: liangz{at}uhnres.utoronto.ca

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