RT Journal Article
SR Electronic
T1 Dense and Overlapping Innervation of Pyramidal Neurons by Chandelier Cells
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 1907
OP 1914
DO 10.1523/JNEUROSCI.4049-12.2013
VO 33
IS 5
A1 Melis Inan
A1 Lidia Blázquez-Llorca
A1 Angel Merchán-Pérez
A1 Stewart A. Anderson
A1 Javier DeFelipe
A1 Rafael Yuste
YR 2013
UL http://www.jneurosci.org/content/33/5/1907.abstract
AB Chandelier (or axo-axonic) cells are a distinct group of GABAergic interneurons that innervate the axon initial segments of pyramidal cells and thus could have an important role controlling the activity of cortical circuits. To understand their connectivity, we labeled upper layers chandelier cells (ChCs) from mouse neocortex with a genetic strategy and studied how their axons contact local populations of pyramidal neurons, using immunohistochemical detection of axon initial segments. We studied ChCs located in the border of layers 1 and 2 from primary somatosensory cortex and found that practically all ChC axon terminals contact axon initial segments, with an average of three to five boutons per cartridge. By measuring the number of putative GABAergic synapses in initial segments, we estimate that each pyramidal neuron is innervated, on average, by four ChCs. Additionally, each individual ChC contacts 35–50% of pyramidal neurons within the areas traversed by its axonal arbor, with pockets of very high innervation density. Finally, ChCs have similar innervation patterns at different postnatal ages (P18–P90), with only relatively small lateral expansions of their arbor and increases in the total number of their cartridges during the developmental period analyzed. We conclude that ChCs innervate neighboring pyramidal neurons in a dense and overlapping manner, a connectivity pattern that could enable ChCs to exert a widespread influence on their local circuits.