title: Frequency of subthreshold oscillations at different membrane potential voltages in neurons at different anatomical positions on the dorsoventral axis in the rat medial entorhinal cortex.
abstract: Neurons from layer II of the medial entorhinal cortex show subthreshold membrane potential oscillations (SMPOs) which could contribute to theta-rhythm generation in the entorhinal cortex and to generation of grid cell firing patterns. However, it is unclear whether single neurons have a fixed unique oscillation frequency or whether their frequency varies depending on the mean membrane potential in a cell. We therefore examined the frequency of SMPOs at different membrane potentials in layer II stellate-like cells of the rat medial entorhinal cortex in vitro. Using whole-cell patch recordings, we found that the fluctuations in membrane potential show a broad band of low power frequencies near resting potential that transition to more narrowband oscillation frequencies with depolarization. The transition from broadband to narrowband frequencies depends on the location of the neuron along the dorsoventral axis in the entorhinal cortex, with dorsal neurons transitioning to higher-frequency oscillations relative to ventral neurons transitioning to lower-frequency oscillations. Once SMPOs showed a narrowband frequency, systematic frequency changes were not observed with further depolarization. Using a Hodgkin-Huxley-style model of membrane currents, we show that differences in the influence of depolarization on the frequency of SMPOs at different dorsal to ventral positions could arise from differences in the properties of the h current. The properties of frequency changes in this data are important for evaluating models of the generation of grid cell firing fields with different spacings along the dorsal-to-ventral axis of medial entorhinal cortex.
authors: Center for Memory and Brain, Department of Psychology and Program in Neuroscience, Boston University, Boston, Massachusetts 02215, USA. motoharu.yoshida@rub.de
authors: Motoharu
authors: M
authors: Yoshida
authors: Lisa M
authors: LM
authors: Giocomo
authors: Ian
authors: I
authors: Boardman
authors: Michael E
authors: ME
authors: Hasselmo
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001683:Biological Clocks / Q000502:physiology*; D055592:Biophysical Phenomena / Q000502:physiology*; D004558:Electric Stimulation; D018728:Entorhinal Cortex / Q000166:cytology*; D005583:Fourier Analysis; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology*; D008959:Models, Neurological; D009431:Neural Conduction / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D020318:Rats, Long-Evans