Cre‐expressing neurons in visual cortex of Ntsr1‐Cre GN220 mice are corticothalamic and are depolarized by acetylcholine

Cre‐expressing neurons in visual cortex of Ntsr1‐Cre GN220 mice are corticothalamic and are depolarized by acetylcholine

The Journal of Comparative Neurology, September 2017

28884467

Sofie Charlotte Sundberg, Sarah Helen Lindström, Gonzalo Manuel Sanchez, Björn Granseth

The Ntsr1-Cre GN220 mouse expresses Cre-recombinase in corticothalamic (CT) neurons in neocortical layer 6. It is not known if the other major types of pyramidal neurons in this layer also express this enzyme. By electrophysiological recordings in slices and histological analysis of the uptake of retrogradely transported beads we show that Cre-positive neurons are corticothalamic and not corticocortical or cortico-claustral types. Furthermore, we show that Ntsr1-Cre-positive cells are immuno-positive for the nuclear transcription factor Forkhead box protein P2 (FoxP2). We conclude that Cre-expression is limited to a specific type of pyramidal neuron: the corticothalamic. However, it appears as not all CT neurons are Cre-expressing; there are indications that the penetrance of the gene is about 90%. We demonstrate the utility of assigning a specific identity to individual neurons by determining that the CT neurons are potently modulated by acetylcholine acting on both nicotinic and muscarinic acetylcholine receptors. These results corroborate the suggested function of these neurons in regulating the gain of thalamocortical transfer of sensory information depending on attentional demand and state of arousal. This article is protected by copyright. All rights reserved.