title: Local-Circuit Phenotypes of Layer 5 Neurons in Motor-Frontal Cortex of YFP-H Mice.
abstract: Layer 5 pyramidal neurons comprise an important but heterogeneous group of cortical projection neurons. In motor-frontal cortex, these neurons are centrally involved in the cortical control of movement. Recent studies indicate that local excitatory networks in mouse motor-frontal cortex are dominated by descending pathways from layer 2/3 to 5. However, those pathways were identified in experiments involving unlabeled neurons in wild type mice. Here, to explore the possibility of class-specific connectivity in this descending pathway, we mapped the local sources of excitatory synaptic input to a genetically labeled population of cortical neurons: YFP-positive layer 5 neurons of YFP-H mice. We found, first, that in motor cortex, YFP-positive neurons were distributed in a double blade, consistent with the idea of layer 5B having greater thickness in frontal neocortex. Second, whereas unlabeled neurons in upper layer 5 received their strongest inputs from layer 2, YFP-positive neurons in the upper blade received prominent layer 3 inputs. Third, YFP-positive neurons exhibited distinct electrophysiological properties, including low spike frequency adaptation, as reported previously. Our results with this genetically labeled neuronal population indicate the presence of distinct local-circuit phenotypes among layer 5 pyramidal neurons in mouse motor-frontal cortex, and present a paradigm for investigating local circuit organization in other genetically labeled populations of cortical neurons.
authors.affiliation: Department of Physiology, Feinberg School of Medicine, Northwestern University Chicago, IL, USA.
authors.forename: Jianing
authors.initials: J
authors.lastname: Yu
authors.forename: Charles T
authors.initials: CT
authors.lastname: Anderson
authors.forename: Taro
authors.initials: T
authors.lastname: Kiritani
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Sheets
authors.forename: David L
authors.initials: DL
authors.lastname: Wokosin
authors.forename: Lydia
authors.initials: L
authors.lastname: Wood
authors.forename: Gordon M G
authors.initials: GM
authors.lastname: Shepherd