title: Oscillatory dynamics in the hippocampus support dentate gyrus–CA3  coupling.
abstract: Gamma oscillations in the dentate gyrus and hippocampal CA3 show variable coherence in vivo, but the mechanisms and relevance for information flow are unknown. We found that carbachol-induced oscillations in rat CA3 have biphasic phase-response curves, consistent with the ability to couple with oscillations in afferent projections. Differences in response to stimulation of either the intrinsic feedback circuit or the dentate gyrus were well described by varying an impulse vector in a two-dimensional dynamical system, representing the relative input to excitatory and inhibitory neurons. Responses to sinusoidally modulated optogenetic stimulation confirmed that the CA3 network oscillation can entrain to periodic inputs, with a steep dependence of entrainment phase on input frequency. CA3 oscillations are therefore suited to coupling with oscillations in the dentate gyrus over a broad range of frequencies.
authors.affiliation: University College London Institute of Neurology, University College London, London, UK. thomas.akam@neuro.fchampalimaud.org
authors.forename: Thomas
authors.initials: T
authors.lastname: Akam
authors.forename: Iris
authors.initials: I
authors.lastname: Oren
authors.forename: Laura
authors.initials: L
authors.lastname: Mantoan
authors.forename: Emily
authors.initials: E
authors.lastname: Ferenczi
authors.forename: Dimitri M
authors.initials: DM
authors.lastname: Kullmann
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D055592:Biophysical Phenomena / Q000187:drug effects / Q000235:genetics; D001703:Biophysics; D056654:CA3 Region, Hippocampal / Q000502:physiology*; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase / Q000235:genetics / Q000378:metabolism; D000075402:Channelrhodopsins; D018891:Dentate Gyrus / Q000502:physiology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D025461:Feedback, Physiological; D025602:Halorhodopsins / Q000235:genetics / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D008845:Microinjections; D008959:Models, Neurological; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009434:Neural Pathways / Q000502:physiology*; D017711:Nonlinear Dynamics; D055095:Optics and Photonics / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar
chemical_list: D000075402:Channelrhodopsins; D025602:Halorhodopsins; D009419:Nerve Tissue Proteins; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase