Electrophysiological properties of genetically identified subtypes of layer 5 neocortical pyramidal neurons: Ca 2+ dependence and differential modulation by norepinephrine

We studied neocortical pyramidal neurons from two lines of bacterial artificial chromosome mice ( etv1 and glt; Gene Expression Nervous System Atlas: GENSAT project), each of which expresses enhanced green fluorescent protein (EGFP) in a different subpopulation of layer 5 pyramidal neurons. In barre...

Full description

Saved in:
Bibliographic Details
Published in:Journal of neurophysiology 2015-04, Vol.113 (7), p.2014-2032
Main Authors: Guan, Dongxu, Armstrong, William E., Foehring, Robert C.
Format: Article
Language:English
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We studied neocortical pyramidal neurons from two lines of bacterial artificial chromosome mice ( etv1 and glt; Gene Expression Nervous System Atlas: GENSAT project), each of which expresses enhanced green fluorescent protein (EGFP) in a different subpopulation of layer 5 pyramidal neurons. In barrel cortex, etv1 and glt pyramidal cells were previously reported to differ in terms of their laminar distribution, morphology, thalamic inputs, cellular targets, and receptive field size. In this study, we measured the laminar distribution of etv1 and glt cells. On average, glt cells were located more deeply; however, the distributions of etv1 and glt cells extensively overlap in layer 5. To test whether these two cell types differed in electrophysiological properties that influence firing behavior, we prepared acute brain slices from 2–4-wk-old mice, where EGFP-positive cells in somatosensory cortex were identified under epifluorescence and then studied using whole cell current- or voltage-clamp recordings. We studied the details of action potential parameters and repetitive firing, characterized by the larger slow afterhyperpolarizations (AHPs) in etv1 neurons and larger medium AHPs (mAHPS) in glt cells, and compared currents underlying the mAHP and slow AHP (sAHP) in etv1 and glt neurons. Etv1 cells exhibited lower d V/d t for spike polarization and repolarization and reduced direct current (DC) gain (lower f- I slope) for repetitive firing than glt cells. Most importantly, we found that 1) differences in the expression of Ca 2+ -dependent K + conductances (small-conductance calcium-activated potassium channels and sAHP channels) determine major functional differences between etv1 and glt cells, and 2) there is differential modulation of etv1 and glt neurons by norepinephrine.
ISSN:0022-3077
1522-1598
DOI:10.1152/jn.00524.2014