title: Emergence of functional subnetworks in layer 2/3 cortex induced by sequential spikes in vivo.
abstract: During cortical circuit development in the mammalian brain, groups of excitatory neurons that receive similar sensory information form microcircuits. However, cellular mechanisms underlying cortical microcircuit development remain poorly understood. Here we implemented combined two-photon imaging and photolysis in vivo to monitor and manipulate neuronal activities to study the processes underlying activity-dependent circuit changes. We found that repeated triggering of spike trains in a randomly chosen group of layer 2/3 pyramidal neurons in the somatosensory cortex triggered long-term plasticity of circuits (LTPc), resulting in the increased probability that the selected neurons would fire when action potentials of individual neurons in the group were evoked. Significant firing pattern changes were observed more frequently in the selected group of neurons than in neighboring control neurons, and the induction was dependent on the time interval between spikes, N-methyl-D-aspartate (NMDA) receptor activation, and Calcium/calmodulin-dependent protein kinase II (CaMKII) activation. In addition, LTPc was associated with an increase of activity from a portion of neighboring neurons with different probabilities. Thus, our results demonstrate that the formation of functional microcircuits requires broad network changes and that its directionality is nonrandom, which may be a general feature of cortical circuit assembly in the mammalian cortex.
authors.affiliation: Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458;
authors.forename: Taekeun
authors.initials: T
authors.lastname: Kim
authors.affiliation: Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458;
authors.forename: Won Chan
authors.initials: WC
authors.lastname: Oh
authors.affiliation: Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458;
authors.forename: Joon Ho
authors.initials: JH
authors.lastname: Choi
authors.affiliation: Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458; Max Planck Institute of Neurobiology, 82152 Martinsried, Germany hyungbae.kwon@mpfi.org.
authors.forename: Hyung-Bae
authors.initials: HB
authors.lastname: Kwon
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D017774:Long-Term Potentiation / Q000502:physiology; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D008959:Models, Neurological; D009415:Nerve Net / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000378:metabolism / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D013003:Somatosensory Cortex / Q000166:cytology / Q000378:metabolism / Q000502:physiology*
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D002118:Calcium
keywords: layer 2/3 cortex; neuronal connectivity; spike timing-dependent plasticity