Referenced in: none

Automatically associated channels: Nav1.2

Title: Action potential initiation in neocortical inhibitory interneurons.

Authors: Tun Li, Cuiping Tian, Paolo Scalmani, Carolina Frassoni, Massimo Mantegazza, Yonghong Wang, Mingpo Yang, Si Wu, Yousheng Shu

Journal, date & volume: PLoS Biol., 2014 Sep , 12, e1001944

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25203314

Abstract
Action potential (AP) generation in inhibitory interneurons is critical for cortical excitation-inhibition balance and information processing. However, it remains unclear what determines AP initiation in different interneurons. We focused on two predominant interneuron types in neocortex: parvalbumin (PV)- and somatostatin (SST)-expressing neurons. Patch-clamp recording from mouse prefrontal cortical slices showed that axonal but not somatic Na+ channels exhibit different voltage-dependent properties. The minimal activation voltage of axonal channels in SST was substantially higher (∼7 mV) than in PV cells, consistent with differences in AP thresholds. A more mixed distribution of high- and low-threshold channel subtypes at the axon initial segment (AIS) of SST cells may lead to these differences. Surprisingly, NaV1.2 was found accumulated at AIS of SST but not PV cells; reducing NaV1.2-mediated currents in interneurons promoted recurrent network activity. Together, our results reveal the molecular identity of axonal Na+ channels in interneurons and their contribution to AP generation and regulation of network activity.