PT - JOURNAL ARTICLE AU - Graf, Jürgen AU - Zhang, Chuanqiang AU - Marguet, Stephan Lawrence AU - Herrmann, Tanja AU - Flossmann, Tom AU - Hinsch, Robin AU - Rahmati, Vahid AU - Guenther, Madlen AU - Frahm, Christiane AU - Urbach, Anja AU - Neves, Ricardo Melo AU - Witte, Otto W. AU - Kiebel, Stefan J. AU - Isbrandt, Dirk AU - Hübner, Christian A. AU - Holthoff, Knut AU - Kirmse, Knut TI - Intraneuronal chloride accumulation via NKCC1 is not essential for hippocampal network development <em>in vivo</em> AID - 10.1101/2020.07.13.200014 DP - 2020 Jan 01 TA - bioRxiv PG - 2020.07.13.200014 4099 - http://biorxiv.org/content/early/2020/07/13/2020.07.13.200014.short 4100 - http://biorxiv.org/content/early/2020/07/13/2020.07.13.200014.full AB - NKCC1 is the primary transporter mediating chloride uptake in immature principal neurons, but its role in the development of in vivo network dynamics and cognitive abilities remains unknown. Here, we address the function of NKCC1 in developing mice using electrophysiological, optical and behavioral approaches. We report that NKCC1 deletion from telencephalic glutamatergic neurons decreases in-vitro excitatory GABA actions and impairs neuronal synchrony in neonatal hippocampal brain slices. In vivo, it has a minor impact on correlated spontaneous activity in the hippocampus and does not affect network activity in the intact visual cortex. Moreover, long-term effects of the developmental NKCC1 deletion on synaptic maturation, network dynamics and behavioral performance are subtle. Our data reveal a neural network function of depolarizing GABA in the hippocampus in vivo, but challenge the hypothesis that NKCC1 is essential for major aspects of hippocampal development.Competing Interest StatementThe authors have declared no competing interest.