Somatostatin Interneurons Promote Neuronal Synchrony in the Neonatal Hippocampus

Publication date: 19 March 2019Source: Cell Reports, Volume 26, Issue 12Author(s): Tom Flossmann, Thomas Kaas, Vahid Rahmati, Stefan J. Kiebel, Otto W. Witte, Knut Holthoff, Knut KirmseSummarySynchronized activity is a universal characteristic of immature neural circuits that is essential for their developmental refinement and strongly depends on GABAergic neurotransmission. A major subpopulation of GABA-releasing interneurons (INs) expresses somatostatin (SOM) and proved critical for rhythm generation in adulthood. Here, we report a mechanism whereby SOM INs promote neuronal synchrony in the neonatal CA1 region. Combining imaging and electrophysiological approaches, we demonstrate that SOM INs and pyramidal cells (PCs) coactivate during spontaneous activity. Bidirectional optogenetic manipulations reveal excitatory GABAergic outputs to PCs that evoke correlated network events in an NKCC1-dependent manner and contribute to spontaneous synchrony. Using a dynamic systems modeling approach, we show that SOM INs affect network dynamics through a modulation of network instability and amplification threshold. Our study identifies a network function of SOM INs with implications for the activity-dependent construction of developing brain circuits.Graphical Abstract

Source: Cell Reports - March 20, 2019 Category: Cytology Source Type: research