title: Contribution of intracolumnar layer 2/3-to-layer 2/3 excitatory connections in shaping the response to whisker deflection in rat barrel cortex.
abstract: This computational study integrates anatomical and physiological data to assess the functional role of the lateral excitatory connections between layer 2/3 (L2/3) pyramidal cells (PCs) in shaping their response during early stages of intracortical processing of a whisker deflection (WD). Based on in vivo and in vitro recordings, and 3D reconstructions of connected pairs of L2/3 PCs, our model predicts that: 1) AMPAR and NMDAR conductances/synapse are 0.52 ± 0.24 and 0.40 ± 0.34 nS, respectively; 2) following WD, connection between L2/3 PCs induces a composite EPSPs of 7.6 ± 1.7 mV, well below the threshold for action potential (AP) initiation; 3) together with the excitatory feedforward L4-to-L2/3 connection, WD evoked a composite EPSP of 16.3 ± 3.5 mV and a probability of 0.01 to generate an AP. When considering the variability in L4 spiny neurons responsiveness, it increased to 17.8 ± 11.2 mV; this 3-fold increase in the SD yielded AP probability of 0.35; 4) the interaction between L4-to-L2/3 and L2/3-to-L2/3 inputs is highly nonlinear; 5) L2/3 dendritic morphology significantly affects L2/3 PCs responsiveness. We conclude that early stages of intracortical signaling of WD are dominated by a combination of feedforward L4-L2/3 and L2/3-L2/3 lateral connections.
authors.affiliation: Department of Neurobiology, Institute of Life Sciences, Jerusalem Il-91904, Israel.
authors.forename: Leora
authors.initials: L
authors.lastname: Sarid
authors.affiliation: Institute for Neuroscience and Medicine, INM-2 Research Centre Jülich, Jülich D-52425, Germany Department of Psychiatry, Psychotherapy, and Psychosomatics, RWTH Aachen University, Aachen D-52074, Germany Jülich-Aachen Research Alliance (JARA)-Brain, Aachen D-52074, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Feldmeyer
authors.affiliation: Department of Neurobiology, Institute of Life Sciences, Jerusalem Il-91904, Israel.
authors.forename: Albert
authors.initials: A
authors.lastname: Gidon
authors.affiliation: Digital Neuroanatomy, Max Planck Florida Institute, Jupiter, FL 33458-2906, USA.
authors.forename: Bert
authors.initials: B
authors.lastname: Sakmann
authors.affiliation: Department of Neurobiology, Institute of Life Sciences, Jerusalem Il-91904, Israel Interdisciplinary Center for Neural Computation, Hebrew University, Jerusalem Il-91904, Israel and Edmond and Lily Safra Center for Brain Sciences, Jerusalem Il-91904, Israel.
authors.forename: Idan
authors.initials: I
authors.lastname: Segev
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000502:physiology*; D003198:Computer Simulation; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D021621:Imaging, Three-Dimensional; D008959:Models, Neurological; D017966:Pyramidal Cells / Q000166:cytology* / Q000502:physiology*; D051381:Rats; D018091:Receptors, AMPA / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013569:Synapses / Q000502:physiology; D014738:Vibrissae / Q000502:physiology*
chemical_list: D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate
keywords: barrel cortex; compartmental model; cortical circuits; synaptic integration; whisker deflection