title: Neocortical Layer 6B as a Remnant of the Subplate - A Morphological Comparison.
abstract: The fate of the subplate (SP) is still a matter of debate. The SP and layer 6 (which is ontogenetically the oldest and innermost neocortical lamina) develop coincidentally. Yet, the function of sublamina 6B is largely unknown. It has been suggested that it consists partly of neurons from the transient SP, however, experimental evidence for this hypothesis is still missing. To obtain first insights into the neuronal complement of layer 6B in the somatosensory rat barrel cortex, we used biocytin stainings of SP neurons (aged 0-4 postnatal days, PND) and layer 6B neurons (PND 11-35) obtained during in vitro whole-cell patch-clamp recordings. Neurons were reconstructed for a quantitative characterization of their axonal and dendritic morphology. An unsupervised cluster analysis revealed that the SP and layer 6B consist of heterogeneous but comparable neuronal cell populations. Both contain 5 distinct spine-bearing cell types whose relative fractions change with increasing age. Pyramidal cells were more prominent in layer 6B, whereas non-pyramidal neurons were less frequent. Because of the high morphological similarity of SP and layer 6B neurons, we suggest that layer 6B consists of persistent non-pyramidal neurons from the SP and cortical L6B pyramidal neurons.
authors.affiliation: Institute of Neuroscience and Medicine, INM-2, Research Centre Jülich, D-52428 Jülich, Germany.|Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, D-52074 Aachen, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Marx
authors.affiliation: Institute of Neuroscience and Medicine, INM-2, Research Centre Jülich, D-52428 Jülich, Germany.
authors.forename: Guanxiao
authors.initials: G
authors.lastname: Qi
authors.affiliation: Developmental Neurophysiology, Institute of Neuroanatomy, Centre for Molecular Neurobiology Hamburg (ZMNH), D-20251 Hamburg, Germany.
authors.forename: Ileana L
authors.initials: IL
authors.lastname: Hanganu-Opatz
authors.affiliation: Institute of Physiology, University Medical Centre of the Johannes Gutenberg-University Mainz, D-55128 Mainz, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Kilb
authors.affiliation: Institute of Physiology, University Medical Centre of the Johannes Gutenberg-University Mainz, D-55128 Mainz, Germany.
authors.forename: Heiko J
authors.initials: HJ
authors.lastname: Luhmann
authors.affiliation: Institute of Neuroscience and Medicine, INM-2, Research Centre Jülich, D-52428 Jülich, Germany.|Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, D-52074 Aachen, Germany.|Jülich Aachen Research Alliance, Translational Brain Medicine (JARA Brain), D-52074 Aachen, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Feldmeyer
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D016764:Cell Polarity; D003712:Dendrites / Q000502:physiology / Q000648:ultrastructure; D049229:Dendritic Spines / Q000502:physiology / Q000648:ultrastructure; D007091:Image Processing, Computer-Assisted; D019579:Neocortex / Q000033:anatomy & histology* / Q000166:cytology / Q000000981:diagnostic imaging; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000502:physiology / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000166:cytology / Q000254:growth & development
keywords: 3D morphology; axonal and dendritic domain; density maps; polarity; somatosensory barrel cortex