title: Robustness of sensory-evoked excitation is increased by inhibitory inputs to distal apical tuft dendrites.
abstract: Cortical inhibitory interneurons (INs) are subdivided into a variety of morphologically and functionally specialized cell types. How the respective specific properties translate into mechanisms that regulate sensory-evoked responses of pyramidal neurons (PNs) remains unknown. Here, we investigated how INs located in cortical layer 1 (L1) of rat barrel cortex affect whisker-evoked responses of L2 PNs. To do so we combined in vivo electrophysiology and morphological reconstructions with computational modeling. We show that whisker-evoked membrane depolarization in L2 PNs arises from highly specialized spatiotemporal synaptic input patterns. Temporally L1 INs and L2-5 PNs provide near synchronous synaptic input. Spatially synaptic contacts from L1 INs target distal apical tuft dendrites, whereas PNs primarily innervate basal and proximal apical dendrites. Simulations of such constrained synaptic input patterns predicted that inactivation of L1 INs increases trial-to-trial variability of whisker-evoked responses in L2 PNs. The in silico predictions were confirmed in vivo by L1-specific pharmacological manipulations. We present a mechanism-consistent with the theory of distal dendritic shunting-that can regulate the robustness of sensory-evoked responses in PNs without affecting response amplitude or latency.
authors.affiliation: Computational Neuroanatomy Group, Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany; Bernstein Center for Computational Neuroscience, 72076 Tübingen, Germany; Graduate School of Neural Information Processing, University of Tübingen, 72074 Tübingen, Germany;
authors.forename: Robert
authors.initials: R
authors.lastname: Egger
authors.affiliation: Network Imaging Group, Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany;
authors.forename: Arno C
authors.initials: AC
authors.lastname: Schmitt
authors.affiliation: Network Imaging Group, Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany; Department of Behavior and Brain Organization, Center of Advanced European Studies and Research, 53175 Bonn, Germany;
authors.forename: Damian J
authors.initials: DJ
authors.lastname: Wallace
authors.affiliation: Digital Neuroanatomy, Max Planck Florida Institute, Jupiter, FL 33458 marcel.oberlaender@tuebingen.mpg.de bert.sakmann@mpfi.org.
authors.forename: Bert
authors.initials: B
authors.lastname: Sakmann
authors.affiliation: Computational Neuroanatomy Group, Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany; Bernstein Center for Computational Neuroscience, 72076 Tübingen, Germany; Digital Neuroanatomy, Max Planck Florida Institute, Jupiter, FL 33458 marcel.oberlaender@tuebingen.mpg.de bert.sakmann@mpfi.org.
authors.forename: Marcel
authors.initials: M
authors.lastname: Oberlaender
authors.affiliation: Network Imaging Group, Max Planck Institute for Biological Cybernetics, 72076 Tübingen, Germany; Department of Behavior and Brain Organization, Center of Advanced European Studies and Research, 53175 Bonn, Germany;
authors.forename: Jason N D
authors.initials: JN
authors.lastname: Kerr
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology* / Q000502:physiology; D003198:Computer Simulation; D003712:Dendrites / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D007395:Interneurons / Q000502:physiology; D008959:Models, Neurological; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000502:physiology*; D051381:Rats; D009435:Synaptic Transmission / Q000502:physiology*; D014738:Vibrissae / Q000502:physiology
keywords: NMDAR; barrel cortex; cortical column; layer 1; shunting