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NJIT Mathematical Biology Seminar

Tuesday, April 10, 2007, 4:00pm
Cullimore Hall 611
New Jersey Institute of Technology

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Formation of gamma coherent cell assemblies by oriens lacunosum-moleculare interneurons in the hippocampus: a modeling study

Adriano Tort

Center for Biodynamics
Boston University

Gamma frequency (30-80 Hz) network oscillations have been observed in the hippocampus during several behavioral paradigms, where they are often modulated by a theta frequency (3-11 Hz) oscillation. Interneurons of the hippocampus have been shown to be crucially involved in rhythms generation and several subtypes with distinct anatomy and physiology have been described. In particular, the oriens lacunosum-moleculare (O-LM) interneurons were shown to synapse on distal apical dendrites of pyramidal cells and to spike preferentially at theta frequency, even in the presence of gamma field oscillations. O-LM cells have also recently been shown to present higher axonal ramification in the longitudinal axis of the hippocampus. By using a hippocampal network model composed of pyramidal cells and two types of interneurons (O-LM and basket cells), we show here that the O-LM interneurons lead to gamma coherence between anatomically distinct cell modules. We thus propose that this would be a mechanism of coupling longitudinally distant gamma oscillators in the hippocampus.