Nonlinear dendritic integration in CA1 pyramidal neurons during locomotion.

Abstract

Event Abstract Back to Event Nonlinear dendritic integration in CA1 pyramidal neurons during locomotion. Jeff Magee1* and Katie Bittner1 1 Howard Hugues Medical Institute, Janelia Farm, United States Most neuronal circuits receive at least two functionally distinct input types (intrinsic vs. extrinsic; sensory vs. motor; etc). In many pyramidal neuron based microcircuits integration of these two input signals can proceed nonlinearly through the production of active dendritic voltage signals. For example, appropriately timed, perisomatically located, hippocampal (SC) and distal dendrite targeting entorhinal (EC3) input produces a distal dendritic Ca2+ plateau potential that drives burst firing output from CA1 pyramidal neurons in vitro. Related signals have been observed in neocortical pyramidal neurons. Until recently it was unknown whether these events occurred in vivo and, if so, during what behavioral states. Here we used simultaneous whole-cell patch and field potential recordings in head-fixed mice running on a linear track treadmill to study this dendritic plateau driven burst firing (plateaus) in CA1 neurons. We find that during locomotion dendritic plateau potentials occur within the neuron’s place field with initiation probability peaking near the peak of the firing field. Plateaus produce a large (32±4mV; n=12), slow (duration; 51±7ms) somatic depolarization that appears similar to that measured in vitro. Interestingly, plateaus exhibit a dramatic level of theta-phase modulation (~97%) that peaks late in the theta cycle (~330°). This late phase peak in plateau potential initiation is near the theta-phase preference of EC3 inputs, suggesting a theta-phase dependent interaction of SC and EC3 inputs. We tested this idea by manipulating the phase of SC inputs by injecting phase adjusted theta frequency currents into CA1 somas. Biasing AP firing earlier in the theta phase decreased plateau probability to ~48% of control whereas biasing AP firing later in phase increased plateau probability 276%. We next directly examined the role of EC3 inputs by inactivating the EC3 axons in CA1 via local light activation of axons expressing archaerhodopsin. This manipulation reduced the probability of plateau initiation by ~40% and decreased the duration of the plateaus ~60%. These data indicate that CA1 pyramidal cells compare theta-phase relations of SC and EC3 inputs with backpropagating action potentials acting as a link between the two isolated subcellular input integration compartments. Keywords: Ca spikes, Hippocampus, in vivo, Entorhinal Cortex, supervised learning Conference: 4th NAMASEN Training Workshop - Dendrites 2014, Heraklion, Greece, 1 Jul - 4 Jul, 2014. Presentation Type: Poster presentation Topic: dendritic integration and compartmentalization Citation: Magee J and Bittner K (2014). Nonlinear dendritic integration in CA1 pyramidal neurons during locomotion.. Front. Syst. Neurosci. Conference Abstract: 4th NAMASEN Training Workshop - Dendrites 2014. doi: 10.3389/conf.fnsys.2014.05.00020 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 11 Apr 2014; Published Online: 12 Jun 2014. * Correspondence: Dr. Jeff Magee, Howard Hugues Medical Institute, Janelia Farm, Ashburn, VA, United States, mageej@janelia.hhmi.org Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Jeff Magee Katie Bittner Google Jeff Magee Katie Bittner Google Scholar Jeff Magee Katie Bittner PubMed Jeff Magee Katie Bittner Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.