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This Article Full Text Full Text (PDF) All Versions of this Article: 96/6/2889    most recent 01233.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map 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 ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Orbán, G. Articles by Érdi, P. Search for Related Content PubMed PubMed Citation Articles by Orbán, G. Articles by Érdi, P.

Intrinsic and Synaptic Mechanisms Determining the Timing of Neuron Population Activity During Hippocampal Theta Oscillation

Gerg Orbán^1,2, Tamás Kiss^1,3 and Péter Érdi^1,3

¹Department of Biophysics, KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest; ²Collegium Budapest, Institute for Advanced Study; Budapest, Hungary; and ³Center for Complex Systems Studies, Kalamazoo College, Kalamazoo, Michigan

Submitted 23 November 2006; accepted in final form 20 July 2006

Hippocampal theta (3–8 Hz) is a major electrophysiological activity in rodents, which can be found in primates and humans as well. During theta activity, pyramidal cells and different classes of interneurons were shown to discharge at different phases of the extracellular theta. A recent in vitro study has shown that theta-frequency oscillation can be elicited in a hippocampal CA1 slice by the activation of metabotropic glutamate receptors with similar pharmacological and physiological profile that was found in vivo. We constructed a conductance based three-population network model of the hippocampal CA1 region to study the specific roles of neuron types in the generation of the in vitro theta oscillation and the emergent network properties. Interactions between pairs of neuron populations were studied systematically to assess synchronization and delay properties. We showed that the circuitry consisting of pyramidal cells and two types of hippocampal interneurons [basket and oriens lacunosum-moleculare (O-LM) neurons] was able to generate coherent theta-frequency population oscillation. Furthermore, we found that hyperpolarization-activated nonspecific cation current in pyramidal cells, but not in O-LM neurons, plays an important role in the timing of spike generation, and thus synchronization of pyramidal cells. The model was shown to exhibit the same phase differences between neuron population activities found in vivo, supporting the idea that these patterns of activity are determined internal to the hippocampus.