title: Post-Inhibitory Rebound Spikes in Rat Medial Entorhinal Layer II/III Principal Cells: In Vivo, In Vitro, and Computational Modeling Characterization.
abstract: Medial entorhinal cortex Layer-II stellate cells (mEC-LII-SCs) primarily interact via inhibitory interneurons. This suggests the presence of alternative mechanisms other than excitatory synaptic inputs for triggering action potentials (APs) in stellate cells during spatial navigation. Our intracellular recordings show that the hyperpolarization-activated cation current (Ih) allows post-inhibitory-rebound spikes (PIRS) in mEC-LII-SCs. In vivo, strong inhibitory-post-synaptic potentials immediately preceded most APs shortening their delay and enhancing excitability. In vitro experiments showed that inhibition initiated spikes more effectively than excitation and that more dorsal mEC-LII-SCs produced faster and more synchronous spikes. In contrast, PIRS in Layer-II/III pyramidal cells were harder to evoke, voltage-independent, and slower in dorsal mEC. In computational simulations, mEC-LII-SCs morphology and Ih homeostatically regulated the dorso-ventral differences in PIRS timing and most dendrites generated PIRS with a narrow range of stimulus amplitudes. These results suggest inhibitory inputs could mediate the emergence of grid cell firing in a neuronal network.
authors.affiliation: Center for Memory and Brain.|Department of Psychological and Brain Sciences.
authors.forename: Michele
authors.initials: M
authors.lastname: Ferrante
authors.affiliation: Center for Memory and Brain.|Department of Psychological and Brain Sciences.|Graduate Program for Neuroscience (GPN).
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Shay
authors.affiliation: Center for Memory and Brain.|Department of Psychological and Brain Sciences.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Tsuno
authors.affiliation: Center for Memory and Brain.
authors.forename: G
authors.initials: G
authors.lastname: William Chapman
authors.affiliation: Center for Memory and Brain.|Department of Psychological and Brain Sciences.|Graduate Program for Neuroscience (GPN).|Center for Systems Neuroscience, Boston University, Boston, MA 02215, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Hasselmo
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002412:Cations / Q000378:metabolism; D003198:Computer Simulation; D018728:Entorhinal Cortex / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008839:Microelectrodes; D008959:Models, Neurological; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D046509:Tissue Culture Techniques
chemical_list: D002412:Cations
keywords: entorhinal cortex; hyperpolarization-activated cation current (Ih); inhibition; post-inhibitory spikes; stellate cells