Extrinsic GABAergic innervation of developing neocortical layer 1 in organotypic slice co-cultures. Dammerman, R S, Noctor, S C, & Kriegstein, A R J Comp Neurol, 423(1):112–120, United States, July, 2000.
abstract   bibtex   
Afferents from the zona incerta (ZI) of the ventral thalamus contribute to the dense, transient gamma-aminobutyric acid (GABA)ergic fiber plexus in layer 1 of the developing rodent somatosensory cortex. Incertocortical axons contact the distal apical dendrites of postmigratory cortical pyramidal cells. Although recent work has shown that these GABAergic incertocortical fibers are likely to provide widespread fast synaptic excitation of pyramidal cells in layers 2-6 during peak periods of cortical synaptogenesis, little is known about the mechanisms by which these axons project to the neocortex and are confined to layer 1. Here we characterize organotypic slice co-cultures in which a region of embryonic diencephalon containing the ZI is maintained adjacent to a region of embryonic somatosensory cortex. Diencephalic explants from transgenic mice expressing enhanced green fluorescent protein (EGFP) enabled direct visualization of diencephalocortical connections. Isochronic co-cultures exhibited diencephalocortical fiber ingrowth immunoreactive for both GABA and the presynaptic vesicle-associated protein synaptophysin that was restricted to neocortical layer 1. This pattern of lamina-specific diencephalocortical ingrowth occurred irrespective of placement of the afferent explant, and persisted in the absence of action potential activity and GABA(A) receptor activation. Heterochronic co-cultures containing older cortex demonstrated that the cortical explants remain permissive for lamina-specific ingrowth through the first postnatal week. Organotypic slice cocultures provide a system in which to study the mechanisms underlying the layer 1-specific ingrowth of extrinsic GABAergic inputs to the perinatal neocortex.
@ARTICLE{Dammerman2000-jq,
  title    = "Extrinsic {GABAergic} innervation of developing neocortical layer
              1 in organotypic slice co-cultures",
  author   = "Dammerman, R S and Noctor, S C and Kriegstein, A R",
  abstract = "Afferents from the zona incerta (ZI) of the ventral thalamus
              contribute to the dense, transient gamma-aminobutyric acid
              (GABA)ergic fiber plexus in layer 1 of the developing rodent
              somatosensory cortex. Incertocortical axons contact the distal
              apical dendrites of postmigratory cortical pyramidal cells.
              Although recent work has shown that these GABAergic
              incertocortical fibers are likely to provide widespread fast
              synaptic excitation of pyramidal cells in layers 2-6 during peak
              periods of cortical synaptogenesis, little is known about the
              mechanisms by which these axons project to the neocortex and are
              confined to layer 1. Here we characterize organotypic slice
              co-cultures in which a region of embryonic diencephalon
              containing the ZI is maintained adjacent to a region of embryonic
              somatosensory cortex. Diencephalic explants from transgenic mice
              expressing enhanced green fluorescent protein (EGFP) enabled
              direct visualization of diencephalocortical connections.
              Isochronic co-cultures exhibited diencephalocortical fiber
              ingrowth immunoreactive for both GABA and the presynaptic
              vesicle-associated protein synaptophysin that was restricted to
              neocortical layer 1. This pattern of lamina-specific
              diencephalocortical ingrowth occurred irrespective of placement
              of the afferent explant, and persisted in the absence of action
              potential activity and GABA(A) receptor activation. Heterochronic
              co-cultures containing older cortex demonstrated that the
              cortical explants remain permissive for lamina-specific ingrowth
              through the first postnatal week. Organotypic slice cocultures
              provide a system in which to study the mechanisms underlying the
              layer 1-specific ingrowth of extrinsic GABAergic inputs to the
              perinatal neocortex.",
  journal  = "J Comp Neurol",
  volume   =  423,
  number   =  1,
  pages    = "112--120",
  month    =  jul,
  year     =  2000,
  address  = "United States",
  language = "en"
}

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