Single XXXX pyramidal cells trigger sharp waves in vitro by exciting interneurones.

@entity35 @entity1251 @entity2406
UNASSIGNED: @entity2406 ( @entity2406 ) are a hippocampal population activity that has been linked to neuronal representations. We show that @entity2406 in the @entity1251 region of @entity35 hippocampal slices can be triggered by firing of single pyramidal cells. Single action potentials in about a third of pyramidal cells initiated @entity2406 at latencies of 2-5  ms with probabilities of 0.07-0.76. Initiating pyramidal cells evoked field IPSPs (fIPSPs) at similar latencies when @entity2406 were not initiated. Similar spatial profiles for fIPSPs and middle components of @entity2406 , suggested SPW fields reflect repeated fIPSPs. Multiple extracellular records showed initiated @entity2406 tended to start near the stimulated pyramidal cell, while spontaneous @entity2406 could emerge at multiple sites. Single pyramidal cells could initiate 2-6 field IPSPs with distinct amplitude distributions, and typically preceeded by a short-duration, extracellular action potential. Comparison of these initiated fields with spontaneously occurring inhibitory field motifs let us identify firing in different interneurones during the spread of @entity2406 . Propagation away from an initiating pyramidal cell was typically associated with the recruitment of interneurones and field IPSPs that were not activated by the stimulated pyramidal cell. SPW fields initiated by single cells were less variable than spontaneous events, suggesting more stereotyped neuronal ensembles were activated, but neither the spatial profile of fields nor the identities of interneurone firing were identical for initiated events. Single pyramidal cell effects on network events are thus mediated by differing sequences of interneurone firing. This article is protected by copyright. All rights reserved.
