Local-circuit phenotypes of layer 5 neurons in motor-frontal cortex of YFP-H mice

• Published in: Frontiers in Neural Circuits
• Main Authors: Jianing Yu, Charles T Anderson, Taro Kiritani, Patrick L Sheets, David Wokosin, Lydia Wood, Gordon M. G Shepherd
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2008-12-01
• Subjects: layer 5; pyramidal neuron; photostimulation; Synaptic connectivity; cortical microcircuit; Glutamate Uncaging
• Online Access: http://journal.frontiersin.org/Journal/10.3389/neuro.04.006.2008/full

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.